General Surveillance


Public health surveillance is the foundation upon which public health programs are designed to prevent and control diseases. Viral hepatitis infections under surveillance by the CDC include hepatitis A, hepatitis B (acute, chronic, and perinatal), and hepatitis C (acute, chronic, and perinatal). The core component of the national viral hepatitis surveillance system is voluntary notification of cases by state, local, and territorial health departments (HDs) to CDC’s National Notifiable Diseases Surveillance System (NNDSS).

Each state and territory mandates the conditions and diseases that should be reported to HDs when identified by laboratories, health care providers, and health care facilities. Personal identifiable information (PII) is collected to enable HDs to identify cases for follow-up and to implement prevention and control measures.

HDs then notify CDC of cases of conditions that are included on the Nationally Notifiable Condition (NNC) List. The NNC List is established through a collaboration between CSTE and CDC and is based on conditions for which there is mandatory reporting to HDs, laboratory tests approved by the US Food and Drug Administration (FDA), and established CDC/CSTE case definitions. Case notifications do not include PII as CDC lacks the authority to receive that information and does not conduct follow-up or intervention activities on cases.

As new reports of viral hepatitis infection are received, HDs report information to CDC, including diagnosis, event dates (e.g., illness onset date), and demographic data (e.g., state/territory, county, sex, age, race, and ethnicity). Additional information collected through NNDSS includes clinical features, laboratory test results, and risk behaviors or exposures potentially associated with infection. This information is needed to confirm the diagnosis, determine a source of infection, identify others at risk for infection, and inform prevention measures.

National surveillance for viral hepatitis is based on case definitions developed and approved by CSTE in collaboration with CDC, which can be found on the CDC NNDSS website (4). Viral hepatitis infections are required to meet specific age, clinical, laboratory, and epidemiologic linkage criteria before being classified as a case. Newly reported cases of hepatitis A, acute hepatitis B, perinatal hepatitis B, acute hepatitis C, and perinatal hepatitis C are considered incident cases. Newly reported cases meeting the chronic hepatitis B and hepatitis C case definitions may reflect prevalent infections. However, because not all viral hepatitis infections are diagnosed or transmitted to NNDSS, CDC traditionally relies on data sources outside of NNDSS to estimate prevalence, including the National Health and Nutrition Examination Survey (NHANES), Centers for Medicare and Medicaid Services (CMS), insurance claims data, hospital discharge data, commercial laboratory data, and pharmacy data. Section 5.4 describes supplemental data sources that can be helpful in improving the understanding of viral hepatitis epidemiology.

Data from NHANES are used to estimate the prevalence of viral hepatitis among non-institutionalized civilian residents of the United States. Because NHANES does not include or may underrepresent some populations who might have a higher prevalence of viral hepatitis (e.g., people experiencing homelessness, people who are incarcerated, certain racial/ethnic minority populations), prevalence estimates obtained from NHANES underestimate the true prevalence in the United States. In recent years, mortality data from the National Vital Statistics System (NVSS) were added to annual viral hepatitis surveillance summaries.

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Goals of Viral Hepatitis Surveillance

The overarching goals of viral hepatitis surveillance are to inform and evaluate the impact of prevention, control, and progress toward elimination. Viral hepatitis surveillance data help jurisdictions

  • describe trends in new infections and disease burden;
  • detect and monitor outbreaks and guide intervention efforts;
  • Identify populations at risk for acquiring infection (e.g., people who inject drugs (PWID), justice-involved people, and people experiencing homelessness);
  • identify risk behaviors and exposures associated with infection (e.g., non-injection and injection drug use);
  • identify people who require linkage to counseling, medical follow-up and treatment, and hepatitis A and hepatitis B vaccination, as appropriate;
  • describe outcomes associated with infection (e.g., hospitalizations, cancer, and mortality);
  • identify contacts of newly diagnosed infected people requiring referral to counseling and/or immunoprophylaxis, and hepatitis A and hepatitis B vaccination, as appropriate;
  • provide information to develop and monitor viral hepatitis care continua to assess impact of viral hepatitis elimination activities; and
  • support the design, development, implementation, and evaluation of evidence-based screening, vaccination, and treatment programs and policies.

To achieve surveillance goals, the viral hepatitis surveillance system, like all public health surveillance systems, should optimize the attributes, as described in the Principles of Epidemiology in Public Health Practice (5).

  • Simple: The structure and operational process of the surveillance system should be as simple as possible while meeting the objectives.
  • Flexible: The system should be adaptable to changing information needs, operating conditions, case definitions, and technology with little additional time, personnel, or allocated funds.
  • Data quality: The completeness and validity of the data in the surveillance system should be assessed at routine intervals.
  • Acceptability: People and organizations targeted for the system, as case patients and data users, should be willing to participate in the surveillance system.
  • Sensitivity: The sensitivity of a surveillance system describes the ability to detect infections and may also refer to the ability to detect outbreaks.
  • Positive predictive value: Positive predictive value is the fraction of reported cases that actually have the health-related event under surveillance.
  • Representativeness: The cases included in the system should accurately reflect infections in the underlying population.
  • Timeliness: Timeliness reflects the availability of data rapidly enough to take appropriate public health action.
  • Stability: Stability refers to the reliability of data collection and management of surveillance data and availability of those data.

The ideal viral hepatitis surveillance system should include the spectrum of disease from infection to cure or death, be standardized across jurisdictions, informed by jurisdictions, used for public health action, and conducted comprehensively across all jurisdictions and for all viral hepatitis conditions. While not all surveillance systems can meet every criterion, additional investments are expected to result in improvements to viral hepatitis surveillance.

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CDC/CSTE Surveillance Case Definitions

Viral hepatitis surveillance case definitions are developed by CSTE in collaboration with CDC programs.  These case definitions are proposed in CSTE’s Position Statements, which provide uniform criteria for case ascertainment, case classification, and national notification to CDC (6). Changes in case definitions might be needed when there are major clinical advances and changes in laboratory and/or surveillance methodologies. Trends in the number and rate of newly reported cases can be affected by changes in the case definition. CSTE leads the position statement development process (6). References to CSTE position statements, current and historical case definitions, and historical time line for implementation of each nationally notifiable condition are found on the CDC NNDSS website (4). The national notification criteria and print criteria for hepatitis A, hepatitis B, and hepatitis C case statuses, based on the current CSTE Position Statements, are summarized in Table 1-1.

Table 1-1. National notification and print criteria for hepatitis A, hepatitis B, and hepatitis C

Condition National Notification Criteria* Print Criteria
Table 1-1
Hepatitis A Confirmed Confirmed
Acute hepatitis B Confirmed and probable Confirmed and probable
Chronic hepatitis B Confirmed and probable Confirmed and probable
Perinatal hepatitis B Confirmed Confirmed
Acute hepatitis C Confirmed and probable Confirmed and probable
Chronic hepatitis C Confirmed and probable Confirmed and probable
Perinatal hepatitis C Confirmed Confirmed
*The transmission of conditions from health departments to the Centers for Disease Control and Prevention (CDC)’s National Notifiable Diseases Surveillance System (NNDSS).
The standards upon which CDC can publish cases, as determined by the Council of State and Territorial Epidemiologists (CSTE) and CDC and listed in CSTE Position Statements.
Download of this table: PDF

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Reporting of Viral Hepatitis Conditions to the HD

Jurisdictions establish mandatory reporting requirements that specify which conditions must be reported to the HD, what attributes of the condition should be included in the report, and the timeline for reporting. Thus, reporting requirements vary by jurisdiction. Reporting sources usually include laboratories, health care facilities, and health care providers. Vital records and medical records can provide additional information on reported cases. Section 5.4 describes how various data sources can be used for viral hepatitis surveillance. The following are the viral hepatitis conditions that are currently recommended by CSTE to be reportable to the HD:

  • Hepatitis A
  • Acute hepatitis B
  • Chronic hepatitis B
  • Perinatal hepatitis B
  • Hepatitis B during pregnancy
  • Acute hepatitis C
  • Chronic hepatitis C
  • Perinatal hepatitis C

While not nationally notifiable, hepatitis C during pregnancy is a condition of public health concern and has ramifications for surveillance. Jurisdictions might also receive negative laboratory results and liver functions tests to improve the accuracy of case ascertainment and classification, examine trends in screening, monitor care continua, and calculate overall disease prevalence. However, the utility of these data is dependent on the jurisdiction’s ability to store and process high volumes of data, as well as the jurisdiction’s legal authority for receiving negative laboratory results. In most cases, negative laboratory results are used only if they are linked to a positive result. Negative laboratory results can be used to identify cases that are classifiable as acute due to test conversion, false-positive test results, cases that have cleared infection, and hepatitis B reactivations and hepatitis C re-infections. Recommended reportable laboratory results for each viral hepatitis condition are found in Sections 2.5 (hepatitis A), 3.4 (hepatitis B), and 4.4 (hepatitis C).

Most HDs have already established strategies to inform laboratories, health care facilities, and health care providers about reporting requirements. Direct outreach to major reporting sources is effective and allows the reporting facilities to ask questions about reporting suspected cases. It is important for viral hepatitis surveillance staff to collaborate with other surveillance staff in the HD to assure that automated systems for capturing electronic laboratory data are accurate and consistent, and that reporting sources receive information about how to report viral hepatitis cases.

In some jurisdictions, programs such as syringe services programs (SSPs) and substance use disorder (SUD) treatment facilities might not have a clear means to report case information. Identifying information needed to create a case and ensure deduplication in the surveillance system might not be obtainable on cases from SSPs, because collection of identifying information can be a barrier to people receiving services. Further, under 42 Code of Federal Regulations (CFR) Part 2 (7), patient records created by federally funded programs for the treatment of SUD are protected; this regulatory prohibition on sharing information without consent of the client does not include an exemption for public health. To address these potential barriers, HD surveillance staff should collaborate with these facilities to discuss options that will allow for timely and accurate reporting while ensuring patient confidentiality and compliance with federal law.

To ensure complete reporting of perinatal hepatitis B and hepatitis C cases, HDs should work with birthing facilities to allow reporting of all live births from a gestational parent living with hepatitis B or hepatitis C. Birthing facilities should be provided with a brief, standardized reporting form and written directions about when and how to submit information to the appropriate HD.

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Submission of Notifiable Conditions to CDC

HDs can transmit many case reports for viral hepatitis infections to CDC using standard NNDSS event codes; however, CSTE determines which conditions are notifiable to CDC (8). The term “notifiable” indicates that CSTE recommends state and territorial HDs transmit these conditions to NNDSS (9). Table 1-2 lists the nine viral hepatitis conditions that can be transmitted to NNDSS and the corresponding NNDSS event codes. While hepatitis D and hepatitis E are not nationally notifiable infectious conditions (9), NNDSS event codes are available for jurisdictions in which they are reportable conditions.

Table 1-2. Viral hepatitis conditions with corresponding National Notifiable Diseases Surveillance System (NNDSS) event codes and national notification criteria

Hepatitis A, acute 10110 Yes
Hepatitis B, acute 10100 Yes
Hepatitis B, perinatal 10104 Yes
Hepatitis B, chronic 10105 Yes
Hepatitis C, acute 10101 Yes
Hepatitis C, perinatal 50248 Yes
Hepatitis C, chronic 10106 Yes
Hepatitis D, acute* 10102 No
Hepatitis E, acute 10103 No
Condition NNDSS Event Code National Notification Criteria
*Hepatitis D is considered a coinfection or superinfection that can only occur in the presence of hepatitis B virus infection.
Downloads of this table: PDF | PPT

Each week, state and territorial HDs transmit case reports of viral hepatitis conditions to NNDSS. The CDC Division of Viral Hepatitis (DVH) developed and provided case report forms that contain data elements necessary for case ascertainment, case classification, case investigation, and national notification. The latest case report form can be found on the CDC DVH website (10). Jurisdictions might opt to collect additional variables to aid in case ascertainment, investigation, characterization, and program evaluation. The CDC case report form was developed based on recommendations from CSTE and serves as a guide for surveillance notification. All viral hepatitis cases must be transmitted electronically to NNDSS. See Section 1.8 for information on data transmission mechanisms for viral hepatitis case notifications to NNDSS.

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Data Elements for Jurisdictional Reporting and National Notification

For viral hepatitis cases that are nationally notifiable to CDC, the following data elements are requested for transmission to NNDSS:

  • Core standardized data elements: For surveillance data to be useful at the national level, all case reports of notifiable viral hepatitis conditions should be transmitted to NNDSS with a set of core standardized data elements as listed in the current CDC viral hepatitis case report form (10). Core elements contain information needed to classify and characterize cases. As jurisdictions transition to HL7 case notification under the NNDSS Modernization Initiative, data elements collected should follow the specifications in the message mapping guides (11).
  • Unique patient identifiers: Using unique identifiers allows jurisdictions to facilitate patient follow-up and link surveillance data with health care data. Patient names and other PII (e.g., date of birth and social security number) are typically stored in the surveillance database maintained by each jurisdiction. Most PII is not transmitted to NNDSS. Policies for ensuring patient privacy and security of data should be in place for any system maintaining patient information. When any type of database is established, the confidentiality of individual identifying information should be ensured according to applicable laws and regulations. See Section 1.11 for guidelines regarding security and confidentiality. CDC uses state- or territory-generated case-level unique identifiers to discuss individual cases with jurisdictions.
  • Morbidity and Mortality Weekly Report (MMWR) week and year: Jurisdictions assign MMWR week and MMWR year in accordance with NNDSS guidance. Guidance is found on the CDC NNDSS website.
  • Data elements from laboratory reports: Electronic reporting can improve timeliness and completeness of data. State and territory rules and regulations for laboratory reporting of viral hepatitis infection markers should include requirements to promptly report available test results to public health authorities, including the patient’s contact information and health care provider.
    Reports of positive test results should also include results for other laboratory markers (including those that are non-positive, negative, or undetectable) relevant to the condition or case classification evaluated on a patient at the same time, including serum alanine aminotransferase (ALT) levels, total bilirubin results, and pregnancy status, if available.
    Negative test results, though not reportable in every jurisdiction, are useful for detecting test conversions, ruling out other conditions causing the same clinical presentation, and detecting resolved or cleared infections. Laboratory reports usually contain demographic information (e.g., name, date of birth, sex, address at time of report, current address, and phone number). This information can be used to locate the patient to obtain information that might not be available on the laboratory report (e.g., race, ethnicity, country of birth, and relevant risk history) and provide linkage to care and follow-up, as indicated.
  • Obtaining relevant risk history on acute cases: People with acute infection should be investigated to determine relevant risk history. The exposure period for ascertaining risk is 15–50 days for hepatitis A, 60–150 days for acute hepatitis B, and 14–182 days for acute hepatitis C prior to the symptom onset date. If the symptom onset date is unknown, the date that the patient first tested positive for the infection can be used as a proxy. Table 1-3 lists the epidemiologic risk behaviors or exposures and groups at risk for hepatitis A, hepatitis B, and hepatitis C as described in the most recent CSTE Position Statements and CDC resource pages for health professionals (12-14). People >18 years of age and pregnant people are recommended to receive HBV and HCV testing, regardless of risk behaviors or exposures (15).

Table 1-3. Epidemiologic risk behaviors, risk exposures, and groups at risk for hepatitis A, hepatitis B, and hepatitis C

Hepatitis A Hepatitis B Hepatitis C
Table 1-3
  • Injection drug use
  • Non-injection drug use
  • Incarceration
  • Experience of homelessness/unstable housing
  • Household contact (non-sexual)
  • Sexual contact with a person with confirmed or suspected hepatitis A
  • Sexual or other practices that lead to fecal-oral contact
  • Men who have sex with men*
  • Exposure to contaminated food or water
  • Close contacts of adopted children newly arriving from countries with high or intermediate hepatitis A endemicity
  • International travel to high or intermediate endemic countries


  • Injection drug use
  • Non-injection drug use
  • Incarceration
  • Experience of homelessness/unstable housing
  • Surgery, dialysis, or other medical procedures
  • IV infusions or injections as part of health care (inpatient or outpatient)
  • Accidental stick/puncture with a needle or other sharp object contaminated with blood
  • Receipt of a blood transfusion, tissue product, or organ transplant
  • Sexual or household contact with a person with confirmed or suspected hepatitis B
  • History of sexually transmitted infections
  • Men who have sex with men*
  • Birth to an infected gestational parent
  • Non-commercial tattoo or body piercing
  • Dental work or oral surgery
  • Other exposure to blood or bodily fluids (not including risk behaviors or exposures listed above)
  • Injection drug use
  • Non-injection drug use
  • Incarceration
  • Experience of homelessness/unstable housing
  • Surgery, dialysis, or other medical procedures
  • IV infusions or injections as part of health care (inpatient or outpatient)
  • Accidental stick/puncture with a needle or other sharp object contaminated with blood
  • Receipt of a blood transfusion, tissue product, or organ transplant
  • HIV infection
  • Sexual practices that result in exposure to blood
  • Birth to an infected gestational parent
  • Non-commercial tattoo or body piercing
  • Dental work or oral surgery
  • Other exposure to blood (not including risk behaviors or exposures listed above)
*Men who have sex with men are recommended by the Advisory Committee on Immunization Practices to receive hepatitis A and hepatitis B vaccination.
†Gestational parent is defined in this context as the parent who gave birth.
‡HIV infection is not a risk factor for hepatitis C. People with hepatitis C and HIV share risk behaviors or exposures; therefore, co-infection is common.
Downloads of this table: PDF | PPT

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Data Quality Reviews and Dissemination

Frequent evaluation of surveillance data for quality, including completeness and timeliness, is essential for identifying aspects of surveillance that need improvement. The quality and completeness of surveillance data can be improved by increasing awareness of viral hepatitis case reporting requirements among laboratories, health care facilities, and health care providers through outreach and collaboration and providing feedback on missing or invalid data fields. Timeliness of surveillance data can be measured by monitoring the average length of time in days required for each step in the surveillance process (e.g., date of specimen collection, date results were received by the HD, follow-up investigation date, and when the local HD transfers the information to the state/territorial HD).

Jurisdiction Data Quality Reviews and Dissemination

Data Quality Reviews

Jurisdictions conducting viral hepatitis surveillance are encouraged to develop protocols to ensure data quality. The protocol might entail:

    • determining if all major clinical and public health laboratories are consistently reporting viral hepatitis laboratory tests,
    • performing regular assessments of viral hepatitis surveillance data to assess data quality (e.g., assessment of invalid values and case and condition classification audits), and
    • assessing data completeness and supplementing surveillance data with data from other sources to improve data completeness, when available.
  • Weekly Data Quality Reviews
    Weekly data quality procedures might include:
    • conducting a quality assurance review of 5% of paper laboratory reports entered by each data entry team member or 5% of electronic laboratory reports received (or fewer, depending on the total volume of laboratory reports) and providing feedback on incomplete or invalid data fields and
    • developing a centralized case notification process in which all reports of viral hepatitis conditions that are submitted by field or community-based staff are manually reviewed and approved by viral hepatitis surveillance leads, which can help to improve workflows and data quality prior to transmission to NNDSS.
  • Quarterly and Annual Data Quality Reviews
    Quarterly and annual data quality procedures depend on a jurisdiction’s surveillance system and ability to routinely investigate cases. For example, in states and territories using the National Electronic Disease Surveillance System (NEDSS) Base System (NBS), the following procedures can be conducted on viral hepatitis investigations for the prior and current calendar year:
    • resolving investigations that have no notification or a pending notification >30 days from the investigation start date;
    • updating the case status from probable to confirmed when additional confirmatory information is received after the investigation start date;
    • resolving investigations with a case status of “suspected,” along with those classified as having an “other non-notifiable case status,” that have been open for >30 days from the investigation start date;
    • de-duplicating* investigations for the same condition that are not evident of a hepatitis C reinfection;
    • conducting a query on viral hepatitis investigations when quarterly and end-of-year CDC DVH quality assurance surveillance reports are received to determine if numbers match;
    • performing end-of-year CDC data validation and completing activities 30 days prior to the NNDSS closeout date;

*When de-duplicating, keep the earliest investigation, change the remaining investigations to ‘not a case’ or append as a single event to the initial report, and associate all laboratory reports with the earliest investigation, if applicable. For cases of hepatitis C reinfection, some jurisdictions are creating a local condition specific for reinfection as opposed to creating a new acute condition to maintain deduplication.

Full data completeness might not be possible for some variables that are often missing on case and laboratory reports (e.g., race, ethnicity, pregnancy status, country of birth, and patient address). Inclusion of demographic information on case and laboratory reports is determined by state/territorial regulations.

Following up on all cases may not be possible, for example on high-volume conditions like chronic hepatitis B and hepatitis C in jurisdictions with large populations. HDs will need to balance the benefits of data completeness with the public health resources needed to obtain this information. Where data collection is resource-intensive, a statistical approach that yields a representative sample of cases to be used to infer demographics or other characteristics might be considered to help direct prevention and resource efforts.

Data Dissemination

Jurisdictions have various mechanisms for sharing viral hepatitis surveillance data internally and externally.

Internal reports might include:

  • a weekly line list of acute cases for the week prior and year-to-date, which allows for the timely detection of unusual trends or cases of potential public health importance requiring prompt attention;
  • use of workflows and automated reports that allow close monitoring of newly reported acute cases of viral hepatitis infection; or
  • regular summary reports of HIV, sexually transmitted infections (STIs), tuberculosis, and viral hepatitis co-infections, which may be distributed to internal staff via secure dashboard (e.g., Tableau or PowerBI).

External reports might include:

  • annual surveillance reports containing state/territory- and county-level case counts and incidence rates of viral hepatitis cases, as well as overall summaries of condition-specific risk behaviors or exposures and outcomes (e.g., hospitalizations and deaths);
  • a comprehensive epidemiologic profile that includes additional data (e.g., HIV, STI, tuberculosis, and opioid overdose surveillance, vital records, hospital discharge, and testing and treatment data) to complement viral hepatitis surveillance data and document disease burden;
  • abstracts on important topics to be submitted to applicable conferences throughout the year; and
  • regular (e.g., quarterly) project-specific progress reports to be distributed to partners, stakeholders, and the public (statewide and by region).

Jurisdictions should develop standard operating procedures for managing requests for surveillance data. Data requests should be handled through a secure management and tracking system, with established standards for turnaround time. Data privacy and suppression standards should be established and applied to these requests, considering that some local jurisdictions may have very few cases.

National Data Quality Reviews and Dissemination

Data Quality Reviews

CDC conducts weekly internal analyses to assess the quality of data transmitted to NNDSS. CDC then follows up with HD viral hepatitis surveillance staff to discuss any apparent data inconsistencies (including data entry and transmission errors) along with concerns regarding data timeliness and completeness.

  • Weekly Data Quality Reviews
    Weekly reviews of surveillance data provide valuable information on data quality that may be indicative of coding or data entry errors. Additionally, these reviews can reveal early signals of clusters, outbreaks, or cases of public health importance that may occur along jurisdictional borders or multiple states.
  • CDC’s Office of Public Health Data, Surveillance, and Technology (OPHDST) updates publicly available provisional viral hepatitis data in tables from CDC WONDER,, and CDC Stacks and disseminates these each week (16).
  • Quarterly Data Quality Reviews
    On a quarterly basis, DVH provides summaries of data to HDs to ensure data received by CDC are consistent with jurisdictional reports. Any inconsistencies are then addressed through discussions between OPHDST, DVH program staff, and the jurisdiction, to ensure agreement of case counts and case information.
  • Annual Data Quality Reviews
    Every April, an end-of-year data quality report for the previous MMWR year is produced by OPHDST and sent to each state and territorial HD for final review. This step is done before the window for data submission officially closes, by which time the state/territorial epidemiologist reviews and approves the final end-of-year data. After data close-out, which typically occurs in May following the evaluation year, the data are considered frozen, and jurisdictions are unable to make further changes or corrections to the closed-out national data.
  • Jurisdictions transmitting case data via HL7 can still transmit updates to historical CDC data after the close-out date; however, these updates are not reflected in the closed-out data file used by OPHDST and DVH for producing annual surveillance summaries. These processes ensure the continued reliability of reported information.

Data Dissemination

CDC generates annual aggregated summaries of finalized data from states and territories, and publishes the findings on CDC WONDER,, and CDC Stacks (16). Annual surveillance summaries of case-level data from states are published on the DVH website (17). Annual DVH surveillance summaries contain case counts and incidence rates of cases of hepatitis A, hepatitis B, and hepatitis C as well as overall summaries of condition-specific risk behaviors or exposures and outcomes (e.g., hospitalizations and deaths).

The report also includes hepatitis A, hepatitis B, and hepatitis C-related death counts and rates overall, and by sex, age, race/ethnicity, and geography of residence as obtained from US Multiple Cause of Death data.

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Data Transmission Mechanisms for National Notification

Viral hepatitis case reports are transmitted to NNDSS through one of three separate electronic data transmission streams.

  • The National Electronic Telecommunications System for Surveillance (NETSS) is the oldest of the three data transmission mechanisms. First launched in 1990, NETSS can capture approximately 50 core and extended variables on a 2-page case report form. The NETSS case report form has not been updated since NETSS was first launched; therefore, variables collected do not necessarily fully characterize the current epidemiology of viral hepatitis infections in the United States. NETSS is not person-based.
  • The National Electronic Disease Surveillance System Base System (NBS) enables HDs to create and send standards-based case notifications to NNDSS. Through NBS, HDs can send and receive extended data elements, including person-level data and additional laboratory and risk information beyond what can be transmitted using NETSS.
  • The NNDSS Health Level Seven Message Mapping Guide (HL7) is the most recent standard for viral hepatitis data transmission to NNDSS. Transmitting case reports via HL7 utilizes the most recent case report form (10) and ensures the ability to receive all pertinent case information, including person-level data. The specifications for HL7 implementation can be found on the CDC NNDSS website (11).
  • Under OPHDST’s Data Modernization Initiative, CDC is working to enhance case surveillance and reduce burden on HDs participating in the NNDSS.

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Cases and Clusters of Potential Public Health Importance

Weekly reviews of acute case surveillance data not only provide valuable information on data quality, but also provide early signals of clusters or outbreaks or cases of significance that require further follow-up. Decisions about follow-up should be prioritized depending on the strength of the signal, whether other indicators of risk are present (e.g., overdose and active HIV or STI transmission), and the available resources to address the problem. To detect cases and clusters of public health interest, jurisdictions should conduct routine data review.

Although not a comprehensive list, the following scenarios provide examples that may signal the need for further public health investigation:

  • cases of hepatitis A or acute hepatitis B among people who were previously vaccinated (to characterize possible vaccine failures);
  • cases of hepatitis A among people born after 2005 or reported cases of hepatitis B among people born after 1990 (to distinguish between failure of vaccine and failure to vaccinate);
  • cases of hepatitis B or hepatitis C among people of childbearing age who are or have the potential to become pregnant (to detect possible perinatal transmission);
  • cases of perinatal hepatitis B and hepatitis C (to identify perinatal transmission);
  • cases of acute hepatitis B or hepatitis C in unusual or vulnerable demographic groups (e.g., older people [e.g., >70 years of age], and those in a residential facility or other congregate setting [including long-term care or corrections]); and
  • cases of seroconversion or acute hepatitis B or hepatitis C in patients receiving hemodialysis.

Possible Outbreaks

An outbreak is defined as the occurrence of more cases of disease than expected in a given area or among a specific group of people over a particular time period. Prompt detection of outbreaks can significantly reduce further transmission. For example, early detection of hepatitis A transmission among PWUD or people experiencing homelessness can prompt local public health officials to administer hepatitis A vaccine to people at high-risk in the outbreak-affected area quickly.

Similarly, early detection of an outbreak of acute hepatitis B or hepatitis C among PWID may facilitate targeted interventions (e.g., access to SSPs, medication for opioid use disorder [MOUD], viral hepatitis treatment, and contact investigation). Detailed guidance on viral hepatitis outbreaks can be found on the CDC DVH Viral Hepatitis Outbreaks website.

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Case Investigation

Reports from laboratories, health care facilities, health care providers, and other data sources indicative of viral hepatitis should prompt a case investigation. Comprehensive surveillance requires a full investigation of all positive laboratory reports and suspected cases. However, not all HDs have the ability to conduct comprehensive viral hepatitis surveillance due to the high volume of positive laboratory reports and inadequate resources.

Jurisdictions are encouraged to develop a list of cases to prioritize for investigations. Jurisdictions might also consider leveraging intersecting surveillance, prevention, and care systems to obtain case information. Some jurisdictions conduct investigations by interviewing a representative sample of patients and their providers, including cases and clusters of potential public health importance.

This section provides general guidance for viral hepatitis case investigation. More detailed guidance for each viral hepatitis condition can be found in Sections 2.8 (hepatitis A), 3.6.5 (acute and chronic hepatitis B), 3.7.5 (hepatitis B during pregnancy and perinatal hepatitis B), 4.6.5 (acute and chronic hepatitis C), and 4.7.5 (hepatitis C during pregnancy and perinatal hepatitis C).

Cases of viral hepatitis require investigation to

  • obtain clinical, laboratory, epidemiologic linkage information to assist in case classification;
  • obtain demographic and risk information to more accurately characterize the epidemiology of the infection and inform prevention and control activities;
  • assess whether the patient requires education, harm-reduction services, provider referral, or other medical follow-up services, as appropriate; and
  • identify contacts requiring post-exposure prophylaxis, testing, or harm reduction services.

Investigation should be conducted to determine whether a case meets the criteria of the CDC/CSTE surveillance case definition. Cases of public health importance will require a more in-depth, timely investigation to collect patient and case-contact information and coordinate referral for counseling, vaccination, and treatment, if appropriate. Case investigation may involve acquiring any of the following types of information.

Information from the Laboratory

Reporting of laboratory test results is mandated by state/territory rules, regulations, or laws. Viral hepatitis surveillance activities generally begin when a HD receives laboratory results of viral hepatitis testing on serum from blood samples submitted by health care providers. The reports generally include demographic information about the patient (e.g., name, date of birth, sex, and identification numbers). The report also includes the name and address of the reporting laboratory, specimen collection date, date the tests were conducted, and name and address of the provider or authority who ordered the tests. Pregnancy status should also be included on the laboratory report if testing was done as part of a prenatal test panel.

Information from the Health Care Provider or Medical Records

The following types of information might be obtainable from medical records.

  • Demographic Information. Includes name, date of birth, sex at birth, current gender, race, ethnicity, and residential address (including zip code).
  • Clinical features. Includes reason for testing, illness onset date, clinical signs and symptoms, co-infections, outcomes (e.g., hospitalization status, date of death), and whether an alternate diagnosis is suspected.
  • Diagnostic test results. Laboratory confirmation of viral hepatitis requires one or more positive test result(s) for the viral hepatitis condition. Laboratory data also contribute to the determination of acuity of infection and the presence of alternative diagnoses.
  • Risk behaviors or exposures. If the ordering provider assessed the patient’s risk history, this information might be obtainable from the medical records.
  • Vaccination information. Obtaining hepatitis A and hepatitis B vaccination history might be done via the patient’s provider or immunization registry.

Information from the Patient

Unless the source of infection is known, patients should be contacted for an interview using the jurisdiction-specific case investigation form. Decisions to contact the patient are often jurisdiction-specific and depend on available resources. In many situations, patient contact is reserved for those cases deemed highest priority for preventing further transmission or referral to care. The patient interview should ideally include the following components.

  • Epidemiologic link. Ascertain whether there was an epidemiologic link to a laboratory-confirmed viral hepatitis case consistent with the criteria in the CDC/CSTE case definitions.
  • Risk behaviors or exposures. Determine the most likely mode of transmission by asking about potential behaviors or exposures relevant to the specific viral hepatitis condition and incubation period.
  • Education and referral for follow-up services. Assess whether the patient requires education or other follow-up services, including harm reduction and hepatitis A and hepatitis B vaccination, as appropriate. Patients should be counseled on how to prevent transmission to others and referred for further counseling and treatment.
  • Identification of contacts requiring postexposure prophylaxis. If resources allow, assess whether the window to provide postexposure prophylaxis is still open and coordinate referral for postexposure prophylaxis, testing, and treatment as appropriate.

Risk behaviors or exposures can be obtained from the provider and/or patient. Under the HIPAA Privacy Rule (45 C.F.R. 164.512(b)) (18), a public health authority is authorized to collect and receive patient health information for the purpose of preventing and/or controlling disease, injury or disability, including public health surveillance, public health investigations, and public health interventions. Therefore, acquiring these records and/or speaking with the provider should be considered routine for authorized public health professionals.

Considerations for Investigating Populations or Settings at Risk for Rapid Disease Transmission

  • People experiencing homelessness. The circumstances surrounding homelessness vary widely, not just geographically, but also from person to person. These factors will likely present challenges for viral hepatitis investigations and should be considered when attempting to contact, investigate, and navigate people experiencing homelessness through the investigation and needed services. People experiencing homelessness often do not have a reliable phone number, necessitating implementation of other strategies (e.g., working with community partners or messaging apps).
  • It might also be difficult to ascertain risk behaviors or exposures among people experiencing homelessness during their incubation period and to determine potential exposure to others in congregate settings (e.g., homeless shelters and soup kitchens [for hepatitis A]). People experiencing homelessness often have infrequent access to health care; further, they may mistrust government organizations because of past stigma and trauma.
  • Partnering with those who serve populations experiencing homelessness, including local government, nonprofit, and religious organizations, can facilitate access to this population. These organizations might be able to assist with locating patients and gathering information about exposures and contacts. People experiencing homelessness are effective gatekeepers to their own communities and might be willing to help facilitate outreach efforts. People experiencing homelessness often do not have transportation, health insurance, or resources required for testing and/or treatment. Community resources (e.g., homeless shelters; health care services for the homeless; free testing events; food, housing, and patient assistance programs; and free clinics) can provide important treatment and prevention services and culturally competent outreach based on trust built over time.
  • People who use drugs. People who use either injection or non-injection drugs might be difficult to reach and distrustful of government agencies offering help due to past histories of stigma and discrimination as well as fear of arrest for illicit drug use. Further, they might be less likely to share complete information, or they may have incomplete recall. Partnering with organizations that serve this population, (e.g., SSPs, behavioral health providers, and SUD treatment facilities) and identifying and employing a champion within the population might be effective ways to gather information about potential exposures and contacts in need of postexposure prophylaxis and/or treatment.
  • When reaching PWUD, partnership with SSPs and other harm reduction programs with a proven track record of demonstrated trust with PWUD/PWID is helpful while maintaining information security and confidentiality. People should be educated about viral hepatitis transmission, prevention, treatment options, and harm reduction services (e.g., syringe access, MOUD, and naloxone distribution for overdose prevention). Information should be gathered on contacts in need of postexposure prophylaxis.
  • When a case is reported by a SUD treatment facility, it is best to work with the facility to discuss options that will allow for timely and accurate reporting while ensuring patient confidentiality and compliance with 42 Code of Federal Regulations (CFR) Part 2 (7). People in SUD treatment facilities should be educated on harm reduction, testing and other prevention interventions (e.g., vaccination and HIV pre-exposure prophylaxis [PrEP]), treatment initiation, and linkage to ongoing medical care. Current guidelines and strategies for the investigation and prevention of viral hepatitis among PWUD can be found on the CDC website (19). Guidance on how to prepare for, detect, investigate, and respond to a hepatitis C outbreak among PWID can be found on the CDC website (20).
  • People engaging in sexual practices resulting in fecal-oral contact or exposure to blood. Anyone who engages in sexual activity that involves fecal-oral contact are at increased risk for contracting hepatitis A. For hepatitis B and hepatitis C, engaging in anal intercourse with the possibility of mucosal trauma and having multiple sexual partners increase the risk of transmission. HIV-infected men who have sex with men (MSM) are also reported to have higher rates of HCV infection and reinfection (21, 22). This population might be hesitant to share information about partners or contacts they might have exposed or who might have exposed them. Patients might not have sufficient information about partner contacts to share with public health. Partnering with health care providers and advanced practice providers, including those who serve the lesbian, gay, bisexual, transgender, and queer plus (LGBTQ+) populations, might improve access to this population to enable prevention interventions. Information shared by partners can promote measures to help prevent spread in this community.
  • People in correctional facilities. Cases of viral hepatitis among people who live or work in correctional facilities require intensive investigations, as these settings are frequently associated with substantial transmission of viral hepatitis infections (23). The ability to conduct case investigations in correctional facilities can vary by correctional jurisdiction, and many barriers exist for case and case-contact investigation (e.g., limited access, high turnover in correctional facilities and inability to find cases or contacts). When possible, jurisdictions should attempt to develop partnerships with correctional facility health care providers/infection preventionists and management staff to establish partnership and allow for the collection of necessary information. Depending on the correctional facility, health staff might be willing to conduct interviews on behalf of the HD. However, investigations must be conducted in a way that shares minimal information with custodial staff to protect patient confidentiality. Knowing the viral hepatitis testing and vaccination policies of the jurisdictional correctional facilities, including the movement of people through the corrections system, is important.
  • Vaccination and education are important, particularly in congregate settings such as correctional facilities. People who are incarcerated should be made aware of the risks of sharing personal items (e.g., razors, nail clippers, and toothbrushes). Education should also be provided on behavioral risks while incarcerated, including IDU, high-risk sexual contact, tattoos, and piercings. It is also important that correctional facilities make supplies available to prevent transmission in these settings.
  • People exposed in health care settings. There are many challenges to identifying and investigating possible health care-associated transmission of viral hepatitis, including (but not limited to) ensuring that the exposure was truly health care-related, gaining access to medical records for follow-up, potential for patient notification, and identifying potential breach(es) in infection control. If the case involves a person with a complex medical history, it might be challenging to identify which health care facility and procedures were involved in disease transmission. Molecular testing, while not available in all jurisdictions, has proven to be a useful tool in these investigations where available. CDC has developed guidelines and tools to assist in the investigation of health care-associated transmissions (24).
  • Establish relationships early with state health care-associated infections (HAI) coordinator (25) and the state agencies that oversee licensing and survey of health care facilities within the health jurisdiction, if possible. These colleagues can provide useful support and guidance in health care-associated investigations and might have established relationships with staff who work at these facilities. It is also important to work with infection control practitioners at health care facilities to discuss early reporting and vigilance regarding test conversion. Find ways to provide training on case investigation to providers outside the hospital setting, such as in dialysis or long-term care facilities, to promote awareness of the process.

Considerations for Documenting and Investigating Cases of Suspected Vaccine Failure

Suspected vaccine failure can occur due to factors associated with the vaccine recipient (e.g., reduced response, non-response, or loss of long-term immunity) and those associated with the vaccine and vaccine administration (e.g., issues related to manufacturing, shipping and cold chain, vaccine storage, administration route, and dose). Because most people will develop protective antibody within 30 days of vaccine series completion (27, 28), a hepatitis A and hepatitis B vaccine failure can be suspected when a person who completed the vaccine series according to the appropriate immunization schedule becomes infected >30 days after completion of the vaccine series. HD surveillance staff should consult with their immunization registry and check medical records to determine the vaccination status of people reported to have hepatitis A and/or hepatitis B.

Any case among a person for whom vaccine failure is suspected should be referred to the vaccine coordinator, who should follow the jurisdiction’s guidelines for investigating vaccine failures. Knowing whether the patient has documentation of being a vaccine responder (e.g., anti-HBs >10 mIU/mL following a completed series) and patient immune status is important, as the vaccine should induce long-term immunity in vaccine responders who are immune-competent. Consideration of the testing date is also important because recent vaccination can result in transient IgM anti-HAV positivity for hepatitis A and transient HBsAg positivity for hepatitis B.

The patient’s provider should be notified, and vaccine manufacturer and lot number should be obtained, if possible. Though these cases are not common in the United States, systematically tracking and analyzing cases of suspected vaccine failures can identify multiple or clusters of vaccine failure cases, allowing public health staff to explore the cause of the failures and determine the appropriate course of action. HDs should notify CDC of cases of vaccine failure through NNDSS by completing the appropriate vaccine information on the case report form. DVH staff are available to provide consultation.

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Security and Confidentiality Guidelines for Surveillance Data

Ensuring secure and confidential data should be a top priority across all levels of public health. CDC’s National Center for HIV, Viral Hepatitis, Sexually Transmitted Disease, and Tuberculosis Prevention (NCHHSTP) recommends standards that can be used by HDs for the secure collection, storage, and use of data while maintaining confidentiality (29). These standards are based on 10 guiding principles that address five major areas: program policies and responsibilities, data collection and use, data sharing and release, physical security, and electronic data security (30). The full Data Security and Confidentiality Guidelines for HIV, Viral Hepatitis, Sexually Transmitted Disease, and Tuberculosis Programs can be found on the CDC National Center for HIV, Viral Hepatitis, Sexually Transmitted Disease, and Tuberculosis Prevention website (29).

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Limitations of Viral Hepatitis Surveillance

Although many jurisdictions have developed strategies to strengthen viral hepatitis surveillance and data collection systems, several limitations remain. Some examples include

  • reporting requirements vary by jurisdiction, resulting in varying levels of quality and completeness of surveillance reports;
  • absence of negative laboratory result reporting can hinder case classification, identification of false-positive test results, and development of laboratory-based hepatitis B and hepatitis C care continua;
  • asymptomatic people are less likely to be diagnosed and identified (particularly relevant for chronic hepatitis C reporting);
  • surveillance data cannot account for undiagnosed infections thus resulting in underreporting and underestimation;
  • illegal and stigmatized behaviors are likely to be underreported in medical records and surveillance investigations, and stigma might deter people from seeking testing or medical care; and
  • investigation of chronic hepatitis B and hepatitis C cases is challenging in jurisdictions.

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