Why Booster Shots Are Important for Preventing and Mitigating the Effects of COVID-19

Key Takeaways
  • The Centers for Disease Control and Prevention (CDC) recommends that everyone 12 years and older, including immunocompromised people, should get a booster shot for COVID-19.

  • Individuals can mix and match vaccines, meaning that you can receive the same vaccine that you got for your original dose(s), or you could choose a booster shot that is made by a different manufacturer (Pfizer, Moderna, or Johnson & Johnson).

There are many simple yet effective ways to protect yourself and your community from COVID-19. This includes preventative measures like wearing a quality mask, testing, and isolating if you’re sick. Natural immunity from previous COVID-19 infections may help protect against new infections, but vaccines — including booster shots — are still the most effective way to prevent and mitigate the effects of COVID-19.

What is a booster shot?

A booster shot is exactly what it sounds like – an additional dose of a vaccine that gives your immune system a “boost” for added protection from disease. All vaccines trigger immunity, but immunity wanes over time. How long it lasts depends on different factors, such as the rate at which a virus replicates and mutates, B and T cell levels, and the number of doses in a vaccination protocol.[1]

Many routine vaccines require more than one shot, including:

  • Hepatitis A
  • Hepatitis B
  • Haemophilus influenzae type B (Hib)
  • Measles-mumps-rubella (MMR)
  • Tetanus, diphtheria, and pertussis (Tdap)
  • Varicella

Health officials also recommend that people of all ages get the seasonal flu shot annually. While it’s not 100% effective in protecting against different strains, it may prevent severe illness. If you have a job that involves travel or working in a medical environment, then you may also need to re-up certain vaccinations more often.

How can booster shots prevent and mitigate the effects of COVID-19?

Since the first COVID-19 vaccine was authorized for use, studies have shown that unvaccinated people are five times more likely to become reinfected and 10 times more likely to be hospitalized or die from COVID-19 than those who are fully vaccinated.[2, 3] And even though immunity from COVID-19 vaccines fades over time, boosters provide added protection against all variants—including the more contagious Omicron. Here’s how COVID-19 booster shots can help to keep everyone safe:

  1. Higher levels of antibodies. Preliminary evidence suggests that an mRNA booster shot given at least six months after the second vaccine dose may result in antibody levels five to ten times higher than after two doses.[4]
  2. Reduce the risk of severe illness, hospitalization, and death. Even after receiving a booster shot, breakthrough infections remain possible (especially with the development of new variants). But most importantly, boosters provide strong protection against severe illness, hospitalization, and death—particularly among older adults and those with pre-existing health conditions.[5]
  3. Limit mild infection and transmission. Even for healthy adults, boosters may help protect against variants of concern as well as limit mild infection and transmission.(source) From a public health perspective, boosters may also help to limit new variants from emerging.
  4. Potentially lower the risk of long COVID. Studies show that being fully vaccinated against COVID-19 minimizes the risk of experiencing long COVID symptoms after an infection occurs. [6] Though large scale studies have yet to determine whether boosters further minimize this risk, evidence shows that boosters will reduce the risk of infection, which in turn may lower the risk of developing long COVID symptoms.


  1. Liu, Y. (2022, February 1). Robust induction of B cell and T cell responses by a third dose of inactivated SARS-CoV-2 vaccine. Nature. https://www.nature.com/articles/s41421-022-00373-7
  2. Office of the Commissioner. (2020, December 12). FDA Takes Key Action in Fight Against COVID-19 By Issuing Emergency Use Authorization for First COVID-19 Vaccine [Press release]. https://www.fda.gov/news-events/press-announcements/fda-takes-key-action-fight-against-covid-19-issuing-emergency-use-authorization-first-covid-19
  3. Scobie, H. M. (2021, September 16). Monitoring Incidence of COVID-19 Cases. . . Centers for Disease Control and Prevention. https://www.cdc.gov/mmwr/volumes/70/wr/mm7037e1.htm
  4. Demonbreun, A. R., Sancilio, A., Vaught, L. A., Reiser, N. L., Pesce, L., McNally, E. M., & McDade, T. W. (2021). Antibody titers before and after booster doses of SARS-CoV-2 mRNA vaccines in healthy adults. medRxiv. https://doi.org/10.1101/2021.11.19.21266555
  5. Moderna COVID-19 booster may protect against variants. (2021, November 9). National Institutes of Health (NIH). https://www.nih.gov/news-events/nih-research-matters/moderna-covid-19-booster-may-protect-against-variants
  6. Antonelli, M., Penfold, R. S., Merino, J., Sudre, C. H., Molteni, E., Berry, S., Canas, L. S., Graham, M. S., Klaser, K., Modat, M., Murray, B., Kerfoot, E., Chen, L., Deng, J., Österdahl, M. F., Cheetham, N. J., Drew, D. A., Nguyen, L. H., Pujol, J. C., . . . Steves, C. J. (2022). Risk factors and disease profile of post-vaccination SARS-CoV-2 infection in UK users of the COVID Symptom Study app: a prospective, community-based, nested, case-control study. The Lancet Infectious Diseases, 22(1), 43–55. https://doi.org/10.1016/s1473-3099(21)00460-6

DISCLAIMER: This article is for general information purposes only, does not constitute medical advice and is not intended to be relied upon for medical diagnosis or treatment. If you are experiencing a medical emergency, dial 911 immediately.