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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?

Millions of Americans have received COVID-19 vaccines, which are safe and effective and undergo intense safety monitoring. Learn more.

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?

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.

Will I have side effects from the COVID-19 vaccine?

Side effects following vaccination are usually mild and last a short time. In fact, experiencing side effects is a sign that your body is working hard to build protection for you. Common side effects include: arm soreness, redness and swelling, and tiredness, headache, muscle pain, chills, fever, and nausea. Learn more on the CDC’s website.

Should I receive a COVID-19 vaccine if I am pregnant or breastfeeding?

Yes, the CDC recommends COVID-19 vaccines for pregnant women and those who are breastfeeding. People who are pregnant or were recently pregnant are at increased risk for a severe outcome from COVID-19. Those who’ve had COVID-19 are also at risk of preterm birth, stillbirth, and possibly other pregnancy complications.

Can my child receive a COVID-19 vaccine?

Children ages 5 and older now can get COVID-19 vaccines. Research into vaccines for children younger than 5 is ongoing. The CDC offers detailed information and guidance about vaccines for children and teens.


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.

Why should children get vaccinated if they are less likely to become severely ill?

While children tend to have milder illness than adults, some children do get very sick and require hospitalization. Some have long-term health problems, and some die. Additionally, children can spread COVID-19 to vulnerable family members, friends, teachers, and others.

Additionally, children who have underlying medical conditions are more at risk for severe illness than children who do not have such conditions. Children can also develop multisystem inflammatory syndrome (MIS-C), in which different body parts become inflamed, such as the heart, lungs, kidneys, brain, skin, eyes, or gastrointestinal organs.

Can I get a flu vaccine and COVID-19 vaccine at the same time?

Yes. The CDC and other experts say it is fine to receive the COVID-19 vaccine and other vaccines – such as the flu shot – at the same time.

Who should get a COVID-19 booster shot?

Adults who received a Pfizer or Moderna mRNA vaccine and are at least 6 months past their second shots are eligible for boosters.

Adults who received the Johnson & Johnson vaccine should receive a second shot two months after their initial vaccine.

Is it true that people can get a different brand of vaccine for their booster shots than they received for their first shot(s) (two-shot series for Pfizer or Moderna; one shot for Johnson & Johnson)?

Yes, people can now select which vaccines they prefer for their booster shots. Learn more.

How do I schedule a booster shot?

First, try contacting the provider that provided your first shots. If you are having difficulty finding a provider for a booster, visit the CDC’s website for guidance on scheduling your next shot.

Do COVID-19 vaccines have microchips?

No. Read about the ingredients contained in each of the available vaccines.

Will I become magnetic if I get vaccinated?

COVID-19 vaccines do not make people who receive them magnetic. The vaccines do not contain ingredients that can cause an electromagnetic field to develop at the site of injection. Additionally, COVID-19 vaccines do not contain metals.

Will the vaccine change my DNA?

COVID-19 vaccines will not change your DNA. They provide instructions to cells to make a protein that is found in the COVID-19 virus. They never integrate into human DNA.

How many COVID-19 vaccine doses do I need?

How many doses you need to complete your primary series depends on which vaccine you receive, according to the CDC. Two doses of the Pfizer-BioNTech vaccine should be given 3 weeks apart. Two doses of the Moderna vaccine should be given 4 weeks apart.

For Johnson & Johnson’s Janssen (J&J/Janssen) vaccine, most people should receive one shot, followed by a booster at least two months later. 

If you receive a vaccine that requires two doses, you should get your second shot as close to the recommended timeline as possible -- but no sooner. 

Also, for your primary vaccine series, you should not change brands until you've completed your primary shots. However, you may mix and match vaccine brands when it comes time for your boosters. 

How long will protection from my COVID vaccines last?

As COVID-19 evolves, so does the science that informs experts how often people in various parts of the world may need to receive additional vaccines. Recent studies show that the protection provided by vaccines may decrease over time. As such, the CDC recommends that everyone 12 and older receive booster shots following their primary vaccination series. 

Learn about timing for all available COVID-19 booster shots.

Should I still get vaccinated if I already had COVID-19? If so, how long should I wait after my recovery?

Yes, experts recommend that you still receive a COVID-19 vaccine following recovery from the virus. While you do get a temporary type of protection called “natural immunity” from having COVID-19, how much protection you have varies depending on whether the infection was mild or severe, the amount of time since you had the infection, and your age. 

Emerging evidence suggests that getting vaccinated after you recover from COVID-19 provides added protection. And there is a big incentive to getting vaccinated: You are less likely to get COVID-19 again. One study showed that people who do not get vaccinated after recovery are more than 2 times as likely to get COVID-19 again than those who do get fully vaccinated.

However, there are a few exceptions. People who've received monoclonal antibody treatments or convalescent plasma, as well as those with a history of multisystem inflammatory syndrome in adults or children (MIS-A or MIS-C), may need to wait a while after recovering before getting vaccinated against COVID-19.