COVIDView: A Weekly Surveillance Summary of U.S. COVID-19 Activity

COVIDView Summary ending on April 11, 2020

Updated Apr. 17, 2020

Download Weekly Summary pdf icon[10 Pages, 2 MB]

Key Updates for Week 15, ending April 11, 2020

This CDC report provides a weekly summary and interpretation of key indicators that have been adapted to track the COVID-19 pandemic in the United States. While influenza-like illness (ILI) declined, it is still elevated and laboratory confirmed COVID-19 activity continues to increase as do COVID-19 severity indicators (hospitalizations and deaths).

Virus

Public health, commercial and clinical laboratories are all testing for SARS-CoV-2, the virus that causes COVID-19, and reporting their results.  The national percentage of respiratory specimens testing positive for SARS-CoV-2 increased from week 14 to week 15 and is as follows:

  • Public health laboratories – increased from 17.3% during week 14 to 17.8% during week 15;
  • Clinical laboratories – increased from 10.6% during week 14 to 11.5% during week 15;
  • Commercial laboratories – increased from 20.6% during week 14 to 22.6% during week 15.
Outpatient and Emergency Department Visits

Two indicators from existing surveillance systems are being monitored to track outpatient or emergency department (ED) visits for potential COVID-19 illness.

  • Nationally, the percentages of visits for influenza-like illness (ILI) and COVID-19-like illness (CLI) are elevated but decreased compared to last week.

Recent changes in health care seeking behavior are likely impacting data from both networks, making it difficult to draw further conclusions at this time. Tracking these systems moving forward will give additional insight into illness related to COVID-19.

Severe Disease

Cumulative COVID-19-associated hospitalization rates since March 1, 2020, are updated weekly. The overall cumulative hospitalization rate is 20.0 per 100,000, with the highest rates in persons 65 years and older (63.8 per 100,000) and 50-64 years (32.8 per 100,000).

Based on death certificate data, the percentage of deaths attributed to COVID-19, pneumonia or influenza increased from 17.8% during week 14 to 18.8% during week 15.

All data are preliminary and may change as more reports are received.

A description of the surveillance systems summarized in COVIDView, including methodology and detailed descriptions of each data component, is available on the surveillance methods page.

Key Points
  • CDC has modified existing surveillance systems, many used to track influenza and other respiratory viruses annually, to track COVID-19.
  • Nationally, the percentage of laboratory specimens testing positive for SARS-CoV-2 continued to increase.
  • Visits to outpatient providers and emergency departments (EDs) for illnesses with symptoms consistent with COVID-19 are elevated compared to what is normally seen at this time of year but decreased compared to levels reported last week.  At this time, there is little influenza virus circulation. The levels of people presenting for care with these symptoms is likely due to COVID-19 but may be tempered by a number of factors including less ILI overall because of widespread adoption of social distancing efforts and changes in healthcare seeking behavior.
  • The overall cumulative COVID-19 associated hospitalization rate is 20.0 per 100,000, with the highest rates in persons 65 years and older (63.8 per 100,000) and 50-64 years (32.8 per 100,000). Hospitalization rates for COVID-19 in older people are higher than what is typically seen early in a flu season.
  • Based on death certificate data, the percentage of deaths attributed to COVID-19, pneumonia or influenza increased from 17.8% during week 14 to 18.8% during week 15.
U.S. Virologic Surveillance

The number of specimens tested for SARS-CoV-2 and reported to CDC by public health laboratories and a subset of clinical and commercial laboratories in the United States are summarized below. At this point in the outbreak, all laboratories are performing primary diagnostic functions; therefore, the percentage of specimens testing positive across laboratory types can be used to monitor trends in COVID-19 activity. As the outbreak progresses, it is possible that different types of laboratories will take on different roles, and the data interpretation may need to be modified. The lower percentage of specimens testing positive in the clinical laboratories compared to the public health and commercial laboratories is likely due to the amount of COVID-19 activity in areas with reporting laboratories and a larger proportion of specimens from children.

Summary of Laboratory Testing Results Reported to CDC*
Week 15
(April 5 – April 11, 2020)
Cumulative since March 1, 2020
No. of specimens tested 680,213 2,313,702
     Public Health Laboratories 75,654 319,885
          Clinical Laboratories 41,136 155,531
          Commercial Laboratories 563,423 1,838,286
No. of positive specimens 145,764 (21.4%) 426,459 (18.4%)
     Public Health Laboratories 13,466 (17.8%) 47,549 (14.9%)
          Clinical Laboratories 4,720 (11.5%) 12,380 (8.0%)
          Commercial Laboratories 127,578 (22.6%) 366,530 (19.9%)

* Commercial and clinical laboratory data represents select laboratories and does not capture all tests performed in the United States.

Public Health Laboratories

This graph displays the number of respiratory specimens tested by age group and the percent positive for SARS-CoV-2 by age group reported to CDC by U.S. State and Local Public Health Laboratories.

Clinical Laboratories

Clinical Laboratories

Commercial Laboratories

Clinical Laboratories

* Commercial laboratories began testing for SARS-CoV-2 in early March, but the number and geographic distribution of reporting commercial laboratories became stable enough to calculate a weekly percentage of specimens testing positive as of March 29, 2020.

Additional virologic surveillance information: Surveillance Methods

Outpatient/Emergency Department Illness

Two syndromic surveillance systems are being used to monitor trends in outpatient and emergency department visits that may be related to COVID-19. Each system monitors a slightly different syndrome, and together these systems provide a more comprehensive picture of mild to moderate COVID-19 illness than either would individually. Both systems are currently being affected by recent changes in healthcare seeking behavior, including increasing use of telemedicine and recommendations to limit emergency department (ED) visits to severe illness, as well as increased social distancing. These changes affect the numbers of people and their reasons for seeking care in the outpatient and ED settings.

ILINet

The U.S. Outpatient Influenza-like Illness Surveillance Network (ILINet) provides data on visits for influenza-like illness (ILI) (fever [≥100F] and cough and/or sore throat) to approximately 2,600 primary care providers, emergency departments and urgent care centers in all 50 states, Puerto Rico, the District of Columbia and the U.S. Virgin Islands. Mild COVID-19 illness presents with symptoms similar to ILI, so ILINet is being used to track trends of mild to moderate COVID-19 illness and allows for comparison with prior influenza seasons.

Nationwide during week 15, 2.9% of patient visits reported through ILINet were due to ILI. This percentage is above the national baseline of 2.4% but represents the third week of a decline after three weeks of increase beginning in early March. The percentage of visits for ILI decreased in all age groups. Nationally, laboratory confirmed influenza activity as reported by clinical laboratories decreased to levels usually seen in summer months which, along with changes in healthcare seeking behavior and the impact of social distancing, is likely driving the decrease in ILI activity.

* Age-group specific percentages should not be compared to the national baseline.

* Age-group specific percentages should not be compared to the national baseline.

On a regional levelexternal icon, the percentage of outpatient visits for ILI ranged from 1.3% to 8.3% during week 15; all regions reported a decreased percentage of outpatient visits for ILI compared to week 14 and five regions are below their region-specific baselines.

ILI Activity Levels

Data collected in ILINet are used to produce a measure of ILI activity for all 50 states, Puerto Rico, the District of Columbia and New York City. The mean reported percentage of visits due to ILI for the current week is compared to the mean reported during non-influenza weeks, and the activity levels correspond to the number of standard deviations below, at or above the mean.

The number of jurisdictions at each activity level during week 15 and the change compared to the previous week are summarized in the table below and shown in the following maps. The decreasing percentage of visits for ILI described above are reflected in this week’s ILI activity levels.

ILI Activity Levels
Activity Level Number of Jurisdictions
Week 15
(Week ending April 11, 2020)
Compared to Previous Week
Very High 2 -6
High 10 -4
Moderate 6 +2
Low 11 -1
Minimal 24 +9
Insufficient Data* 1 No change
ili-map-1
ili-map-2

*Data collected in ILINet may disproportionally represent certain populations within a state, and may not accurately depict the full picture of influenza activity for the whole state. Differences in the data presented here by CDC and independently by some state health departments likely represent differing levels of data completeness with data presented by the state likely being the more complete.

National Syndromic Surveillance Program (NSSP): Emergency Department (ED) Visits

NSSP is a collaboration among CDC, federal partners, local and state health departments and academic and private sector partners to collect, analyze and share electronic patient encounter data received from multiple healthcare settings. To track trends of potential COVID-19 visits, visits for COVID-19-like illness (CLI) (fever and cough or shortness of breath or difficulty breathing or presence of a coronavirus diagnosis code) and ILI to a subset of emergency departments in 47 states are being monitored. The coronavirus diagnosis code was added to the CLI definition this week after input from public health and community partners. This addition changed the magnitude of the percentage of visits for CLI but it did not change the trends.

Nationwide during week 15, 5.6% of emergency department visits captured in NSSP were due to CLI and 2.5% were due to ILI. This is the third week of decline in percentage of visits for ILI and the second week of decline in percentage of visits for CLI. All 10 HHS regionsexternal icon experienced a decline in percentage of visits for ILI and CLI.

covid-like-illness

Additional information about medically attended outpatient and emergency department visits for ILI and CLI: Surveillance Methods

Hospitalizations

The COVID-19-Associated Hospitalization Surveillance Network (COVID-NET) conducts population-based surveillance for laboratory-confirmed COVID-19-associated hospitalizations in select counties participating in the Emerging Infections Program (EIP) and Influenza Hospitalization Surveillance Project (IHSP) states. COVID-NET-estimated hospitalization rates will be updated weekly.

A total of 6,485 laboratory-confirmed COVID-19-associated hospitalizations were reported by sites between March 1, 2020, and April 11, 2020. The overall cumulative hospitalization rate was 20 per 100,000 population with the highest rates among adults aged 65 years and older (63.8 per 100,000) followed by adults aged 50-64 years (32.8 per 100,000).

laboratory-confirmed COVID-19-associated hospitalizations

Among 1,968 cases with information on race/ethnicity, 43.4% were non-Hispanic white, 32.0% were non-Hispanic black, 11.7% were Hispanic and 12.9% were other race, including unknown race.

Among 1,968 cases with information on race/ethnicity, 43.4% were non-Hispanic white, 32.0% were non-Hispanic black, 11.7% were Hispanic and 12.9% were other race, including unknown race.
Overall 0-4

years

5-17

years

18-49 years 50-64 years 65+

years

N (%) N (%) N (%) N (%) N (%) N (%)
Non-Hispanic White 854 (43.4) 3 (60.0) 3 (33.3) 136 (29.2) 239 (37.5) 473 (55.6)
Non-Hispanic Black 630 (32.0) 0 (0.0) 6 (66.7) 158 (34.0) 229 (35.9) 237 (27.8)
Hispanic 230 (11.7) 2 (40.0) 0 (0.0) 107 (23.0) 82 (12.9) 39 (4.6)
Other 254 (12.9) 0 (0.0) 0 (0.0) 64 (13.8) 88 (13.8) 102 (12.0)

Among 886 hospitalized adults with information on underlying medical conditions, 90% had at least one reported underlying medical condition; the most commonly reported were hypertension, obesity, chronic metabolic disease and cardiovascular disease. Among 7 hospitalized children with information on underlying medical conditions, 71.4% had at least one underlying medical condition; the most commonly reported was asthma.

Additional hospitalization surveillance information: Surveillance Methods  | Additional rate data  |  Additional demographic and clinical data

Mortality Surveillance

The National Center for Health Statistics (NCHS) collects death certificate data from vital statistics offices for all deaths occurring in the United States. Based on death certificate data available on April 16, 2020, 18.8% of all deaths occurring during the week ending April 11, 2020 (week 15) were due to pneumonia, influenza or COVID-19 (PIC). This percentage is above the epidemic threshold of 7.0% for week 15 and has been increasing sharply since the end of February.

This graph shows pneumonia and influenza (P&I) mortality data provided to CDC by the National Center for Health Statistics (NCHS) Mortality Reporting System.

*Data during recent weeks are incomplete because of the lag in time between when the death occurred and when the death certificate is completed, submitted to NCHS and processed for reporting purposes.

Additional NCHS mortality surveillance information: Surveillance Methods  | Provisional Death Counts for COVID-19 | Provisional Death Counts for PICpdf icon