COVID-19 Vaccine FAQs for Healthcare Professionals

CDC now recommends that certain people are now eligible to receive a COVID-19 booster shot, including those who received Moderna and Johnson & Johnson/Janssen COVID-19 vaccines. Get more information and read CDC’s media statement.

Below are answers to commonly asked clinical questions that apply to all authorized COVID-19 vaccines.

For clinical questions on the following specific COVID-19 vaccines, see:

Vaccination Schedule and Use

COVID-19 vaccines are not interchangeable. The safety and effectiveness of a mixed-product series have not been evaluated. Therefore, make every effort to determine which vaccine product was administered as the first dose to ensure your patient completes the vaccine series with the same product. In exceptional situations:

  • When the vaccine product given for the first dose cannot be determined or is no longer available, you may administer any available mRNA COVID-19 vaccine, with a minimum of 28 days between doses.

If a patient received the first dose of an mRNA COVID-19 vaccine but is unable to complete the series with either the same or a different mRNA COVID-19 vaccine (e.g., due to contraindication), you may consider administering a single dose of Janssen COVID-19 Vaccine, with a minimum of 28 days between doses. See contraindications and precautions for more information on use of Janssen COVID-19 Vaccine and additional precautions in people with a contraindication to mRNA COVID-19 vaccines.

Use the following strategies to help ensure patients receive the second dose with the appropriate product and interval between doses:

  • Provide a COVID-19 vaccination record card to every vaccine recipient. Ask recipients to bring their card to their appointment for the second dose. Encourage them to make a backup copy (e.g., by taking a picture of the card with their phone).
  • Encourage vaccine recipients to enroll in v-safe, a free smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins as well as second-dose reminders.
  • Encourage vaccine recipients to enroll in VaxTextSM, a free text-message–based platform, to receive reminders to get their second dose of COVID-19 vaccine.
  • Record each recipient’s vaccination in the immunization information system (IIS).
  • Record vaccine administration information in the patient’s medical record.
  • Make an appointment for the second dose before the vaccine recipient leaves to increase the likelihood that patients will return to the same vaccination provider site for the second dose. Make sure that the recipient has a reminder for the second appointment.

No. You may administer a COVID-19 vaccine and other vaccines without regard to timing. This includes simultaneous administration of a COVID-19 vaccine and other vaccines (including live, attenuated vaccines such as the measles-mumps-rubella [MMR] vaccine) on the same day, as well as coadministration at any time interval. It is unknown whether reactogenicity of a COVID-19 vaccine is increased with coadministration, including with other vaccines known to be more reactogenic, such as adjuvanted vaccines or live vaccines.

When deciding whether to coadminister other vaccines with a COVID-19 vaccine, consider:

  • Whether the patient is behind or at risk of becoming behind on recommended vaccines
  • The patient’s risk of vaccine-preventable disease (e.g., during an outbreak or occupational exposures)
  • The reactogenicity profile of the vaccines

Learn more about coadministration with other vaccines.

Yes. COVID-19 vaccination should not be delayed because of testing for TB infection. Testing for TB infection with one of the immune-based methods, either the TST or an IGRA, can be done before, after, or during the same encounter as COVID-19 vaccination.

Patients who have active TB disease or an illness that is being evaluated as active TB disease can receive a COVID-19 vaccine (note: the presence of a moderate or severe acute illness is a precaution to administration of all vaccines).

People who have received a COVID-19 vaccine can have axillary lymphadenopathy, which may cause a false reading on a mammogram. If it is not possible to schedule the mammogram before COVID-19 vaccination, some experts recommend waiting 4 to 6 weeks after COVID-19 vaccination to schedule the mammogram.

No. COVID-19 booster doses are currently not recommended by the Advisory Committee on Immunization Practices (ACIP), composed of medical and public health experts, who develop recommendations and provide guidance to the CDC Director on the use of vaccines for the general public. Only after a thorough review of the evidence will CDC’s independent advisory committee make recommendations on the use of booster doses of COVID-19 vaccines for the public.

On August 18, 2021, the U.S. Department of Health and Human Services (HHS) announcedexternal icon an operational plan for COVID-19 booster dose administration beginning the week of September 20, 2021. Implementation of the plan is contingent on the findings of the FDA and ACIP. FDA is conducting an independent evaluation to determine the safety and effectiveness of a booster dose of the Pfizer-BioNTech and Moderna mRNA vaccines. ACIP will decide whether to recommend a booster dose based on a thorough review of the scientific evidence.

For guidance on additional dose recommendations of an mRNA COVID-19 vaccine for immunocompromised persons, please visit https://www.cdc.gov/vaccines/covid-19/hcp/immunocompromised-patients.html and https://www.cdc.gov/vaccines/covid-19/clinical-considerations/immunocompromised.html.

Vaccine Indications

Antibody tests for COVID-19 look for the presence of antibodies made in response to a previous infection or vaccination. They are an indicator of the body’s efforts to fight off the SARS-CoV-2 virus. None of the currently authorized SARS-CoV-2 antibody testsexternal icon have been validated to evaluate specific immunity or protection from SARS-CoV-2 infection.

Antibody testing is NOT currently recommended to assess

  • Immunity to COVID-19 following COVID-19 vaccination
  • The need for vaccination in an unvaccinated person

There are several issues to consider when interpreting an antibody test for SARS-CoV-2 infection:

  • Scientists have not yet established a serologic correlate of protection, which is the measurable threshold above which a person is protected against SARS-CoV-2 infection. This makes it difficult to interpret how laboratory results might translate to clinical protection.
  • Antibody testing does not evaluate the cellular immune response, which may also play a role in vaccine-mediated protection.
  • Vaccines trigger antibodies to specific viral protein targets. Currently authorized/approved COVID-19 vaccines induce antibodies to the spike protein but not to the nucleocapsid protein, which is likely detected only after a natural infection with SARS-CoV-2. Therefore, COVID-19-vaccinated people who have not had previous natural infection will receive a negative antibody test result if the antibody test is designed to detect nucleocapsid protein.
  • Antibody tests have different levels of sensitivity (i.e., the true positive rate, or ability to identify people with antibodies to SARS-CoV-2) and specificity (i.e., the true negative rate, or ability to identify those without antibodies to SARS-CoV-2).

For assistance with patient counseling and education related to COVID-19 testing and vaccination, please see:

For more detailed information, please see:

Yes. CDC recommends COVID-19 vaccination for all people with prior COVID-19 infection. However, the timing of the vaccination depends on when a person had SARS-CoV-2 infection and/or when they received treatment.

People with a prior infection: Offer vaccination regardless of history of prior symptomatic or asymptomatic SARS-CoV-2 infection, including to people with prolonged post-COVID-19 symptoms.

While there is no recommended minimum interval between infection and vaccination, current evidence suggests that the risk of SARS-CoV-2 reinfection is low in the months after initial infection but may increase with time due to waning immunity.

People with a history of multisystem inflammatory syndrome in children (MIS-C) or adults (MIS-A): These people may choose to be vaccinated but should consider delaying vaccination until they have recovered from their illness and for 90 days after the date of diagnosis. Considerations for vaccination may include:

  • Clinical recovery from MIS-C or MIS-A, including return to normal cardiac function
  • Personal risk of severe acute COVID-19 (e.g., age, underlying conditions)
  • Level of COVID-19 community transmission and personal risk of reinfection
  • Lack of safety data of COVID-19 vaccines following these illnesses
  • Timing of any immunomodulatory therapies

People with a current infection: Defer vaccination of people with known current SARS-CoV-2 infection until the person has recovered from acute illness (if the person has symptoms) and until criteria have been met for them to discontinue isolation. This recommendation applies to any vaccine, including the first and second doses of COVID-19 vaccine.

For people who previously received passive antibody therapy as part of COVID-19 treatment, defer vaccination for at least 90 days after receipt of passive antibody therapy (monoclonal antibodies or convalescent plasma). This recommendation applies to people who receive passive antibody therapy before receiving any COVID-19 vaccine dose and to those who receive passive antibody therapy after the first dose of an mRNA COVID-19 vaccine but before the second dose, in which case the second dose should be deferred for at least 90 days following receipt of the antibody therapy.

Learn more about COVID-19 vaccination and SARS-CoV-2 infection.

No, your patient may be vaccinated without waiting 90 days. Although people who have received passive antibody therapy as treatment for COVID-19 should wait at least 90 days before vaccination, there is no minimum interval between antibody therapies not specific to COVID-19 treatment and COVID-19 vaccination.

Yes. You may administer any currently FDA-authorized or approved COVID-19 vaccine to people with underlying medical conditions; the Advisory Committee on Immunization Practices (ACIP) does not state a product preference. This includes people with:

  • Immunocompromising conditions or people who take immunosuppressive medication or therapies (For guidance on additional dose recommendations of an mRNA COVID-19 vaccine for immunocompromised persons, please visit https://www.cdc.gov/vaccines/covid-19/hcp/immunocompromised-patients.html and https://www.cdc.gov/vaccines/covid-19/clinical-considerations/immunocompromised.html.)
  • Autoimmune conditions
  • A history of Guillain-Barré syndrome
  • A history of Bell’s palsy
  • A history of dermal filler use

Learn more about vaccinating patients with underlying medical conditions.

As with other vaccines, a moderate or severe illness is a precaution to receiving any currently FDA-authorized or approved COVID-19 vaccine. It is not considered a contraindication. Generally, vaccination should be delayed until the acute illness has improved. However, if you and your patient feel the potential benefits of vaccination outweigh the potential risks, they may receive COVID-19 vaccine.

The following considerations can be used to help the provider conduct a risk assessment for COVID-19 vaccination:

  • Risk of exposure to SARS-CoV-2 (e.g., living in a congregate setting, such as a long-term care facility; occupation)
  • Risk of severe disease or death due to COVID-19 (e.g., because of age or underlying medical conditions)
  • Whether the patient has previously been infected with SARS-CoV-2 and, if so, how long ago
    • Note: Vaccination is recommended for people with a history of COVID-19. However, because the risk of reinfection is low in the months after initial infection, people with a precaution to vaccination and who have had a recent SARS-CoV-2 infection may choose to delay vaccination.

People with a history of an episode of immune-mediated syndrome characterized by thrombosis and thrombocytopenia (e.g., heparin-induced thrombocytopenia) should be offered Moderna COVID-19 Vaccine or Pfizer-BioNTech COVID-19 Vaccine if it has been 90 days or less since their illness resolved. After 90 days, patients may be vaccinated with any FDA-authorized or approved COVID-19 vaccine.

More information is available at: Clinical Care Considerations for COVID-19 Vaccination | CDC

Yes. CDC recommends COVID-19 vaccination for all people who are pregnant, breastfeeding, trying to get pregnant now or who might become pregnant in the future. Pregnant or breastfeeding people are eligible for and can receive any of the currently authorized or approved COVID-19 vaccines; ACIP does not state a product preference. However, you should talk to pregnant, breastfeeding, and postpartum people younger than 50 years old who choose to receive Janssen COVID-19 Vaccine about:

  • The rare but increased risk of thrombosis with thrombocytopenia syndrome (TTS) after receipt of this vaccine
  • The availability of other FDA-authorized or approved COVID-19 vaccines (i.e., mRNA vaccines) for which the risk of TTS has not been observed

Pregnant people with COVID-19 are at increased risk for preterm birth and might be at increased risk for other adverse pregnancy complications and outcomes, such as preeclampsia, coagulopathy, and stillbirth. Additionally, pregnant people with COVID-19 are at increased risk for severe illness when compared with non-pregnant people, including illness that requires hospitalization, intensive care unit admission, mechanical ventilation, or extracorporeal membrane oxygenation.

A growing body of evidence on the safety and effectiveness of COVID-19 vaccination – in both animal and human studies – indicates that the benefits of vaccination outweigh any known or potential risks of COVID-19 vaccination during pregnancy, including:

  • No safety signals in animal studies
  • No adverse outcomes in previous trials of the adenovirus platform that included pregnant people
  • No evidence of COVID-19 vaccines causing infection in the pregnant person or the fetus

If a person becomes pregnant following the first dose of a COVID-19 vaccine that requires two doses (i.e., Pfizer-BioNTech COVID-19 Vaccine or Moderna COVID-19 Vaccine), the second dose should be administered as indicated for the person to have maximum protection.

Encourage pregnant people who get vaccinated to enroll in v-safe, a smartphone-based tool that uses text messaging and web surveys to provide personalized health check-ins after COVID-19 vaccination. A v-safe pregnancy registry has been established to follow outcomes among pregnant people who are vaccinated.

Learn more about vaccination of pregnant or breastfeeding people and considerations for use of the Janssen COVID-19 Vaccine in certain populations.

CDC has a Prevaccination Checklist for COVID-19 Vaccinespdf icon that you can use to screen patients for contraindications and precautions for COVID-19 vaccines.

Vaccine Storage and Handling

CDC requires vaccination providers participating in the COVID-19 Vaccination Program to use a specific type of TMD called a “digital data logger” (DDL) to monitor temperatures. A DDL provides the most accurate storage unit temperature information, including details on how long a unit has been operating outside the recommended temperature range (referred to as a “temperature excursion”). DDLs using a buffered temperature probe provide the most accurate way to measure actual vaccine temperatures. Always use DDLs with a current and valid Certificate of Calibration Testing.

Note that not all DDLs can measure ultra-cold temperatures. For accurate ultra-cold temperature monitoring, it is essential to use an air-probe or a probe designed specifically for ultra-cold temperatures with the DDL.

For the Pfizer-BioNTech COVID-19 vaccine, there are additional considerations for using a TMD with the thermal shipping container. Refer to the Pfizer-BioNTech COVID-19 Vaccine Storage and Handling Summarypdf icon and Pfizer-BioNTech COVID-19 Vaccine web page for more information.

If the vaccine experienced problems during shipment (for example, damage or temperature excursion), contact:

  • Directly distributed vaccine (for example, Pfizer): 800-666-7248 (option 8) or CVGovernment@Pfizer.com.
  • Centrally distributed vaccine (for example, Moderna): McKesson Specialty Customer Service at (833) 343-2703, Monday–Friday, 8 AM–8 PM Eastern Time.

If the vaccine experienced problems after it was received and placed into storage, contact the vaccine manufacturer for guidance on improper storage and handling.

For temperature excursions (out-of-range temperatures), take immediate action:

  • Label the vaccine “Do Not Use” and store at the recommended temperature range until you receive manufacturer guidance.
  • Document the date and length of time of the excursion, storage unit temperature, room temperature, and inventory affected.
  • Record any other relevant information.
  • Contact the manufacturer for guidance on whether to use affected vaccines and whether patients need to be recalled for revaccination.
  • Document the event and action taken for record-keeping requirements.

CDC recommends transporting vaccine in vials. However, there may be instances when the only option is to transport predrawn vaccine in a syringe. U.S. Pharmacopeia includes guidance for transporting predrawn vaccine in syringes in the USP COVID-19 Vaccine Toolkit: Operational Considerations for Healthcare Practitionersexternal icon.

Vaccine Administration

No. While it is important to try to use every dose of vaccine possible, that should not be at the expense of missing an opportunity to vaccinate every eligible person when they are ready to get vaccinated. Strategies to ensure providers do not miss an opportunity to vaccinate every eligible person and limit wastage can be found here: Identification, Disposal, and Reporting of COVID-19 Vaccine Wastagepdf icon.

COVID-19 vaccines are administered by intramuscular injection. For all intramuscular injections, the needle should be long enough to reach the muscle mass and prevent vaccine from seeping into subcutaneous tissue. Ensuring the vaccine is given in the muscle is important to optimize immunogenicity and minimize adverse reactions at the injection site. If vaccine is given subcutaneously with the incorrect needle length, patients may experience more pain, irritation, and redness at the injection site.

Needle gauge and length recommendations vary for adolescents based on age, and for adults based on age, gender, and weight. CDC’s needle gauge and length chartpdf icon, included in the ancillary kits, outlines ACIP’s recommendations for needle length. Other vaccine administration and injection resources can be found in CDC’s Vaccine Administration Resource Library.

To reduce the risk of fake or counterfeit vaccines, dispose of vials and packaging as medical waste by placing vials in a sharps container and packaging in a red medical waste bag. If medical waste containers are in short supply, deface or safely crush packaging materials so they cannot be reintroduced or reproduced. After the products are sufficiently defaced or destroyed, dispose with regular waste.

The disposal process for unused COVID-19 vaccine and diluent may be different. For guidance, contact your jurisdiction’s immunization program.  If advised to dispose of the vaccine, properly dispose of the vaccine as biohazard waste. Never return unused or expired vaccines with the shipping containers back to the manufacturer. Additionally, promptly report any expired or unused vaccine. This helps CDC accurately monitor the amount of vaccine in the field.  Keep in mind that there are no negative consequences for reporting waste, and it will not negatively impact future allocations. CDC recognizes that unused expired vaccine is a normal part of any vaccination program, especially one of this scope and size.

Vaccination Documentation

Vaccination providers enrolled in the COVID-19 Vaccination Program are required to:

  • Document vaccine administration in their medical record systems within 24 hours of administration.
  • Report administration data to the relevant system (i.e., IIS) for the jurisdiction as soon as practicable and no later than 72 hours after administration. See data reporting requirements.
  • Report inventory daily using VaccineFinderexternal icon. In some jurisdictions, providers may report vaccine inventory to the jurisdiction’s IIS for the jurisdiction to upload into VaccineFinder. If you have questions about the process for your jurisdiction, please contact your jurisdiction’s immunization program.
  • Report the following to VAERSexternal icon:
    • Vaccine administration errors
    • Serious adverse events
    • Multisystem inflammatory syndrome
    • Cases of COVID-19 that result in hospitalization or death after the recipient has received COVID-19 vaccine

There are additional requirements for COVID-19 vaccination providers besides documentation (e.g., providing the Fact Sheet for Recipients and Caregivers to vaccine recipients). Please refer to your COVID-19 vaccination provider agreement for all provider requirements.

Some people may have received a COVID-19 vaccine outside of the United States. Consider the following for these patients:

  • People who received an FDA-authorized or approved COVID-19 vaccine and have received all the recommended doses do not need any additional doses. People who received the first dose of an FDA-authorized or approved COVID-19 vaccine that requires two doses do not need to restart the vaccine series in the United States but should receive the second dose as close to the recommended time as possible.
  • People who have received all recommended doses of a COVID-19 vaccine listed for emergency use by the World Health Organization (WHO) do not need any additional doses with an FDA-authorized or approved COVID-19 vaccine. See Interim Clinical Considerations for Use of COVID-19 Vaccines Currently Authorized in the United States for a list of WHO vaccines listed for emergency use.
  • People who have not received all the recommended doses of a COVID-19 vaccine listed for emergency use by WHO may be offered a complete FDA-authorized or approved COVID-19 vaccine series. Wait at least 28 days after the last dose of the non-FDA-authorized vaccine before administering an FDA-authorized or approved COVID-19 vaccine.
  • People who received all or some of the recommended doses of a COVID-19 vaccine not listed for emergency use by WHO and not authorized or approved by FDA may be offered a complete FDA-authorized or approved COVID-19 vaccine series. Wait at least 28 days after the last dose of the non-authorized vaccine before administering an FDA-authorized or approved COVID-19 vaccine.

Under Emergency Use Authorization, there is no VIS for an authorized vaccine. Instead, providers are legally required to provide the FDA-authorized EUA Fact Sheet for Recipients and Caregivers to vaccine recipients or their guardians. There is no VIS yet for the FDA-approved COMIRNATY vaccine. A single Fact Sheet for Recipients and Caregiversexternal icon covers both the authorized Pfizer-BioNTech COVID-19 Vaccine and the FDA-licensed vaccine, COMIRNATY.

The Fact Sheet for Recipients and Caregivers includes:

  • Basic information on COVID-19, symptoms, and what to discuss with a healthcare provider before vaccination
  • Who should and should not receive the vaccine
  • A statement that recipients have the choice to receive the vaccine
  • Vaccine series information
  • Potential and known risks and benefits of the vaccine, including common side effects
  • Information on reporting side effects to VAERS
  • An explanation of what an EUA is and why it is issued
  • Any approved available alternatives for preventing COVID-19
  • Additional resources

No. Although you are required to provide the vaccine-specific Fact Sheet for Recipients and Caregivers to vaccine recipients or their caregivers, you are not required to document that you did so. help facilitate such documentation in electronic medical records/immunization information systems for vaccination providers who choose to do so, CDC is leveraging the existing vaccine information statement (VIS) Code Set infrastructure, barcoding, and URLs to provide the information needed for various systems. This is similar to the electronic system and workflow documentation of the VIS. The barcode at the bottom of the last page of the Fact Sheet for Recipients and Caregivers may be scanned to capture in electronic medical records/immunization information systems that the fact sheet was provided to the vaccine recipient or caregiver.

Vaccine Safety and Efficacy

Adverse events that occur in a recipient following COVID-19 vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS)external icon. Vaccination providers are required by the FDA to report:

  • Vaccine administration errors
  • Serious adverse events
  • Cases of multisystem inflammatory syndrome
  • Cases of COVID-19 that result in hospitalization or death following COVID-19 vaccination

Reporting is encouraged for any other clinically significant adverse event, even if it is uncertain whether the vaccine caused the event. Also, vaccine recipients can report adverse events that occur after vaccination. Information on how to submit a report to VAERS is available at https://vaers.hhs.govexternal icon or by calling 1-800-822-7967. For more information on VAERS, please refer to the VAERS FAQsexternal icon.

The VAERS reporting requirements for COVID-19 vaccines are different from those for routine vaccines licensed in the United States. Healthcare providers are strongly encouraged to report vaccine administration errors involving any licensed vaccine. However, healthcare providers are required to report COVID-19 vaccine administration errors to VAERSexternal icon.

Before vaccination, counsel patients about expected local and systemic side effects.

Common side effects include:

Local reactions:

  • Pain
  • Redness
  • Swelling

Systemic reactions:

  • Tiredness
  • Headache
  • Muscle pain
  • Chills
  • Fever
  • Nausea

If receiving Janssen COVID-19 Vaccine, women younger than 50 years old should be made aware of the rare but increased risk of blood clots with low platelets following vaccination and the availability of other COVID-19 vaccines where this risk has not been observed. Provide recipients or caregivers (as applicable) the EUA Fact Sheet for Recipients and Caregiversexternal icon.

If receiving an mRNA COVID-19 Vaccine (i.e., Pfizer or Moderna), recipients should be made aware of the rare but elevated risk for myocarditis and/or pericarditis, particularly in males aged 12-29 years.  The Advisory Committee on Immunization Practices concluded that the benefits of COVID-19 vaccination to individual persons and at the population level clearly outweighed the risks of myocarditis after vaccination. Provide recipients or caregivers (as applicable) the Pfizer Vaccine Information Fact Sheetexternal icon or the Moderna EUA Fact Sheetexternal icon for Recipients and Caregivers.

Fully vaccinated people with Delta variant breakthrough infections can spread the virus to others. However, vaccinated people appear to be infectious for a shorter period. Additionally, COVID-19 vaccines are effective and offer protection against hospitalization and death. Guidance for fully vaccinated people will continue to be updated as more information becomes available.

No. There is no evidence that any vaccine, including COVID-19 vaccines, impact menstrual cycles or future fertility. People who are trying to become pregnant do not need to avoid pregnancy after COVID-19 vaccination. There is no recommendation for routine pregnancy testing before receipt of a COVID-19 vaccine. For more information, please visit Myths and Facts about COVID-19 Vaccines.

For more information, visit CDC’s When You’ve Been Fully Vaccinated webpage.

Other

All staff supporting COVID-19 vaccination efforts should receive ongoing training as new COVID-19 vaccines become available and recommendations evolve. Review and complete training and core competencies by professional qualification. Additionally, for healthcare professionals new to vaccination, the COVID-19 Vaccination Training Programs and Reference Materials for Healthcare Professionalspdf icon provide a comprehensive list of suggested training and reference materials.

For more immunization training resources, see Resources for Health Care Providers and Immunization Education and Training.

Please contact CDC-INFO for further questions on COVID-19 vaccines.

Page last reviewed: September 22, 2021