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COVID-19 Boosters FAQ

Published April 29th, 2022

At PHM, our team of PhD-led research experts continuously monitor the latest news, research, and developments for new insights on the COVID-19 pandemic to improve the health and safety of our clients. Here’s the latest:

Should I get a booster?

PHM continues to strongly recommend that people who are eligible receive their first booster shot. The booster offers added protection from severe disease and helps strengthen immune response against SARS-CoV-2 (the virus that causes COVID-19). To date, uptake on boosters has been slow: nearly half of the eligible population over the age of 18 and one-third of those over 65 have not received their first booster dose. There are many individuals who can benefit from receiving a first booster.

Should I consider getting a second booster?

On March 29, 2022, the FDA authorized a second booster dose of the Pfizer-BioNTech or Moderna COVID-19 vaccine for all adults 50 and older as well as immunocompromised individuals. Eligible individuals should wait at least 4 months after their first booster of an authorized or approved COVID-19 vaccine before getting their second shot.

PHM recommends a second booster for the following individuals:

  • 65 and older
  • 50 and older with underlying medical conditions that increase risk for severe disease from COVID-19
  • Those who received a primary vaccine and booster dose of Johnson & Johnson’s COVID-19 vaccine at least 4 months ago

The country’s booster strategy is evolving, and the FDA’s Vaccines and Related Biological Products Advisory Committee is developing a coordinated approach for booster doses and timing to address variants.

PHM will continue to monitor the latest research and findings and will provide updated guidance on booster eligibility and schedules.

Will the criteria for a second booster ever change to include those under 50?

Currently, the second booster is only recommended for those over the age of 50 or for individuals who are immunocompromised. However, the emergence of a new variant, the waning of immunity, or the development and availability of a novel vaccine that shows high efficacy against infection/severe disease could change the criteria to include younger members of the population.

Is there a risk in receiving a second booster?

At this time, PHM’s perspective is that there is not enough evidence to broadly recommend second boosters to all individuals in the 50 and above age group. The risks and benefits of a second booster should be weighed for each person in the 50-64 age group based on their exposure risk and general health. Individuals 65 and older should receive a second booster based on age alone.

Aside from the transient side effects of the booster (e.g., fever, body aches, fatigue, injection site soreness), a second booster in young, healthy people could have other potential downsides. “Over-boosting” could dampen long-term immunity, either by interfering with immunity from a prior infection or vaccination or by adversely shaping the immune response through other complex immunological mechanisms.1 2

One benefit of the FDA’s authorization for all those 50 and above to receive a second booster is that it enables individuals to make decisions about their own health. Simply put, if a healthy 50-year-old wants to receive the second booster, they can. 

It is important to consider, though, the varying risk across this age group: for example, a healthy 50-year-old, a 50-year-old with underlying medical conditions, and a healthy 80-year-old all have very different risk profiles. PHM will continue to provide recommendations that follow the latest guidance from the FDA and CDC, so that you can make informed decisions that make sense for you and your family.


  1. Goel, R. R. et al. Efficient recall of Omicron-reactive B cell memory after a third dose of SARS-CoV-2 mRNA vaccine. bioRxiv, 2022.2002.2020.481163, doi:10.1101/2022.02.20.481163 (2022).
  2. Wheatley, A. K. et al. Immune imprinting and SARS-CoV-2 vaccine design. Trends Immunol 42, 956-959, doi:10.1016/ (2021).

About the Author

Dr. Natalya Gertsik, PhD

Managing Practice Director, Health Advisory

Dr. Gertsik leads PHM’s Health Advisory Practice, providing health risk intelligence and strategic guidance on infectious diseases and other emerging health threats to corporate clients. Her Advisory clients at PHM span many industries, including financial services, retail, film production, utilities, real estate, and childcare centers. She brings a wealth of experience from her years as a consultant at McKinsey & Company and her time spent in the lab researching Alzheimer’s disease drugs as part of her PhD thesis.