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COVID-19 Vaccine FAQs

The University of Maryland School of Medicine’s (UMSOM) Center for Vaccine Development and Global Health (CVD) has been at the forefront of COVID-19 vaccine research. As COVID-19 vaccine rollout proceeds across the U.S., we offer answers to frequently asked questions.

Are COVID-19 vaccines safe?

COVID-19 vaccines that have received Emergency Use Authorization (EUA) from the U.S. Food and Drug Administration (FDA) underwent rigorous studies to ensure safety. Watch an FDA video describing the emergency use authorization. Also, learn how federal partners are ensuring the safety of COVID-19 vaccines in the United States.

Should people with allergies receive COVID-19 vaccines?

People with allergies to foods, drugs, or other ingredients that are not in the vaccine can receive it. But people who have had an allergy to polyethylene glycol (abbreviated PEG), an mRNA vaccine component, or to another ingredient called polysorbate, should not receive the Moderna or Pfizer vaccines. Those who have had reactions to a vaccine or injectable therapy that contains multiple components – such as PEG or polysorbate – but are unsure which component caused the allergic reaction have a precaution to vaccination, so they should consult with their doctors prior to receiving the vaccine.

Where can I find the list of ingredients for each vaccine?

To see each vaccine’s ingredients, please visit:

I was asked to provide insurance information for my COVID-19 vaccine appointment. I thought it was free. Will I have a copay?

The vaccine itself is free to you, as the U.S. government purchased all vaccine doses at no cost to individual citizens. However, vaccination providers can charge an administration fee for administering the shot, and they may use the insurance information to be reimbursed by the patient’s insurer. If you do not have insurance or are unable to pay for the vaccine to be administered, you cannot be denied a COVID-19 vaccine.

If my arm was sore after my first COVID-19 vaccine, or if I had a rash or redness at the injection site, should I not get another dose?

Injection-site reactions sometimes occur after vaccination, and people who experience them should still receive the second dose of COVID-19 vaccines.

Is it true that people who’ve received COVID-19 vaccines do not need to quarantine if they’re exposed to COVID-19?

The Centers for Disease Control and Prevention (CDC) recently issued updated quarantine guidelines for people who’ve been vaccinated against COVID-19. Fully vaccinated people who are exposed to someone with suspected or confirmed COVID-19 do not need to quarantine if the following three conditions are met:

  • they are fully vaccinated, meaning it has been at least two weeks since the second dose of a two-dose series, or at least two weeks following receipt of a one-dose vaccine
  • they are within three months of the last dose of COVID-19 vaccine
  • they remain asymptomatic since COVID-19 exposure

Can my child receive a COVID-19 vaccine?

The COVID-19 vaccines that have received EUA from the FDA are both largely for adults and older teens. Specifically, the Pfizer-BioNTech vaccine is authorized for people age 16 and older, and the Moderna vaccine is for people 18 and older.

Studies to assess safety and efficacy in children and adolescents are ongoing.

How do I report adverse reactions to my COVID-19 vaccine?

Adverse reactions should be reported to the Vaccine Adverse Event Reporting System. Reporting is encouraged for any clinically significant adverse event, even if you are unsure if the vaccine is to blame for your issue. Submit a report to VAERS, or call 1-800-822-7967.

Additionally, the CDC developed a new smartphone-based tool, v-safe. It uses text messaging and web surveys for health check-ins following vaccination.

Are you protected longer from COVID-19 infection if you get vaccinated, or if you’ve had a prior infection?

How long “natural immunity”—that is, immunity through a prior COVID-19 infection—lasts varies from person to person. Evidence so far suggests it lasts at least 90 days. We do not yet know how long immunity lasts following vaccination.

What percentage of the United States population needs to be vaccinated in order to achieve herd immunity?

We do not yet know how many people need to be vaccinated in order to achieve “herd immunity,” which refers to enough people protected from becoming infected because they’ve already had COVID-19 or have been vaccinated. The CDC and other experts are studying this issue.

When can I get vaccinated?

The COVID-19 vaccine supply in the U.S. is very limited, but it is expected to improve in late spring and summer 2021. The CDC has provided recommendations about who should be vaccinated first based on determinations made by the Advisory Committee on Immunization Practices, an independent panel of medical and public health experts. However, each state – and in some cases, counties and cities – sets its own vaccine priority groups. Contact your state health department for more information, and read the CDC recommendations for who should get vaccinated first.

If I’ve already had COVID-19, do I still need to be vaccinated?

Yes, you should still be vaccinated as soon as you qualify to do so. If you were treated with monoclonal antibodies or convalescent plasma, you should wait 90 days before getting vaccinated.

I have an underlying medical condition. Can I be vaccinated?

People with certain underlying medical conditions were included in COVID-19 vaccine clinical trials and can receive COVID-19 vaccines as long as they aren’t allergic to any of the vaccine ingredients and haven’t previously had an allergic reaction to a COVID-19 vaccine. As people with certain underlying medical conditions are at increased risk for severe illness from COVID-19, it is important for people in those groups to be vaccinated as soon as they qualify.

Learn more about vaccination considerations for persons with underlying medical conditions from the CDC.