The COVID-19 Booster Shot: Frequently Asked Questions

Note: Information in this article was accurate at the time of original publication. Because information about the COVID-19 booster shot changes rapidly, we encourage you to visit the websites of the Centers for Disease Control & Prevention (CDC), World Health Organization (WHO), and your state and local government for the latest information.

It wasn’t too long ago that people were calculating the day they could feel fully protected by their vaccination, now a booster shot is available and eligibility is expanding. The Food and Drug Administration (FDA) and the Centers for Disease Control and Prevention (CDC) have been busy making decisions about which groups of people are eligible for boosters, and if it’s acceptable to “mix and match” vaccines from different manufacturers for a booster dose. Here are some of your most common questions about the booster shot.

Which COVID-19 booster shots are approved?

The FDA has issued authorization for three boosters: Pfizer-BioNTech, Moderna, and Janssen/Johnson & Johnson. The agency also notes that it is safe to receive a brand of booster that is different from the original vaccine.

At what age is it possible to receive a booster shot?

Adults over age 18 can receive any brand of booster shot. However, the Pfizer-BioNTech vaccine is the only vaccine and booster authorized for children over age 16.

When should I get a COVID-19 booster shot?

For the Pfizer-BioNTech and Moderna vaccines, a booster shot is appropriate six months after completing your primary vaccination series. If you received the Janssen/Johnson & Johnson vaccine, a booster shot is appropriate two months after completing your primary vaccination series.

Although it’s safe to receive a booster shot, do healthy individuals need one? Dr. David Cope from Cope Family Medicine | Ogden Clinic weights in.

“We’re used to having data available quickly and having succinct answers,” says Dr. Cope. “Unfortunately, we are still learning about the COVID-19 virus and how much protection is needed. What we know today is that boosted individuals are better protected against serious illness and transmission of variants including the new Omicron variant.”

Dr. Cope adds “I was skeptical of the value of boosters initially, as my patients will tell you. The vaccination course provides a long-term primer and ample protection against serious illness and death. But studies are now indicating that boosted individuals do not transmit COVID-19 as easily, and that’s becoming especially true as we watch the spread of Omicron.”

Why is a COVID-19 booster shot needed?

New virus strains are frequently identified and research is ongoing about how best to isolate potential new outbreaks to prevent future worldwide episodes such as this one. The second course of action is to develop preventive measures, including vaccines, that can limit the spread and the severity of such viral infection.

In the case of SARS-CoV-2, effective vaccines were available relatively quickly, but not before millions of people worldwide died. Now, with new variants of the virus detected almost weekly, according to researchers, boosters have been developed to strengthen the body’s ability to resist infection from both the original strain and its successive variants. Available vaccines do not entirely prevent illness, and their effectiveness has been shown to diminish over time.

Does the COVID-19 vaccine prevent transmission of COVID-19, the severity of symptoms, or both?

Current research shows that available boosters can make a big difference in COVID-19 transmission, especially for younger people. A recently-completed Israeli study reports that people between the ages of 16 and 49 were 13 times less likely to test positive for COVID-19 after a dose of the Pfizer-BioNTech booster, even though the infection rate was surging in the country at the time.

The results, published in the New England Journal of Medicine, also noted that those 50 and older were 10 times less likely to test positive. And people older than 60 were 12 times less likely to become severely ill and about 15 times less likely to die. The study was completed between August and early October 2021 with a small sampling, but the results were impressive nonetheless. The research was completed prior to the discovery of the Omicron variant, but later studies confirm that the Pfizer-BioNTech booster offers high protection against that strain as well among previously fully-vaccinated people.

Those who receive the booster dose have been shown to have about 25 times the number of antibodies, and also specific T-cells that should work against the newly-identified variant.

Additional Considerations about the COVID-19 Booster Shot

These preliminary results about the boosters, however promising they are, were based on a very small study, and the results are still considered preliminary. However, as with other familiar illnesses, including seasonal influenza and even the common cold (also caused by a type of coronavirus), immunity is achieved over time, and annual boosters are effective at preventing serious illness from new strains of the virus that appear.

No vaccination will provide 100% protection, but right now medical experts agree that the best course of action to prevent serious illness and death from COVID-19 is to become fully vaccinated and to have the booster when recommended.

Should my booster shot be from the same manufacturer as my original vaccination?

The CDC has given the green light to “mix and match” COVID-19 booster shots if they are available. “Interestingly, studies are indicating that people have marginally better protection if they mix doses, such as getting a Moderna booster shot after receiving a Pfizer vaccination course,” says Dr. Cope. “There seems to be just enough difference in those vaccines that by getting a booster than your primary series, you broaden that protection.”

Dr. Cope adds that the two mRNA vaccines seemed to do a better job of boosting than the Johnson and Johnson shot, triggering stronger antibody responses. All boosters worked well in neutralizing Delta and Beta variants. No new safety concerns have emerged so far, and reactogenicity and adverse events have been similar across boosters.

If you have questions about manufacturers and dosages, talk to your healthcare provider about which vaccine booster is best for you.

Are there side effects from the booster shot?

You may get side effects from the booster shot. Side effects usually are mild to moderate and last one to three days. Side effects may include arm soreness, headaches, body aches, tiredness and fever. Serious side effects are rare but may occur after a booster shot.

Is a booster shot free?

Yes, a booster shot is free for anyone who is eligible to get one. If you have insurance, it may be billed, but you will not be charged an administration fee or any other fee.