Pharmacists Explain: Should You Get a COVID-19 Booster Shot or Additional Dose?

Published: October 25, 2021
Hannah Post
By Hannah Post, PharmD
Barbara Young
By Barbara Young, PharmD


What is a booster shot and why do I need one?

A booster shot is a dose of vaccine given after the original vaccine series is complete to give you ongoing protection against disease. The booster reminds the body what the virus looks like and ‘boosts’ the immune system.


The goal of the booster is to help maintain a level of immunity for a longer period. There are many vaccines that require booster shots such as those that prevent tetanus, pertussis, and meningitis. Booster shots are necessary with the COVID-19 vaccines because studies show protection against COVID-19 may decrease over time, especially in certain people.


Who is eligible for a COVID-19 booster shot?

Currently, there are booster recommendations for all three available COVID-19 vaccines in the United States.


If you received a Pfizer-BioNTech or Moderna vaccine, the booster dose should be given at least six months after the second dose of your original series. If you received a Johnson & Johnson vaccine, you are eligible to receive a booster at least 2 months after your vaccine. Individuals have the option to choose which vaccine they receive as a booster dose.


At this time, not everyone needs a booster dose.


If you received a Pfizer-BioNTech or Moderna COVID-19 vaccine, the following groups are eligible for a booster shot at 6 months or more after their initial series:


If you received the Johnson & Johnson COVID-19 vaccine, booster shots are recommended for those who are 18 and older and who were vaccinated two or more months ago.


Should I wait to get a booster shot?

No. The Centers for Disease Control and Prevention (CDC) has provided information on who is eligible for the COVID-19 booster. If you are eligible and it has been at least six months since the last dose, get the shot as soon as possible to continue protection against COVID-19 and its variants.


Are booster shots safe?

Yes. Boosters have proven to be safe. The booster doses contain the same amount of vaccine as the original series. Ongoing research and monitoring will continue to test the efficacy and safety of the booster dose.


What is the difference between a booster shot and an additional dose of the vaccine?

An additional dose of the two-shot COVID-19 vaccines (Pfizer-BioNTech and Moderna) is recommended for people who have weakened immune systems due to either medications or health conditions. Studies show that people with weakened immune systems may not have a strong enough response to the first two doses to be protected against the virus.


An additional dose is recommended at least 28 days after the second dose of the original vaccine (either Pfizer-BioNTech or Moderna). The level of protection against the virus may not be the same in some immunocompromised individuals as the general population, even after an additional dose.


Can my pharmacist help?

Pharmacists can answer your questions COVID-19 vaccines as well as administer COVID-19 vaccines and other immunizations like your yearly flu shot.


With so much information about the COVID-19 vaccines and now additional doses and boosters, pharmacists are the medication experts and an easy source of important information. If you have any questions about whether or not you qualify for an additional dose or booster, speak with a pharmacist today.


By Hannah Post, Pharm.D., and Barbara Young, Pharm.D.



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