COVID-19 Booster Shots

Last week the Center for Disease Control and Prevention (CDC) approved the use of mix-and-match COVID-19 boosters for Americans at high risk of severe illness or infection. Any of the three authorized vaccines in the United States, Pfizer-BioNTech, Moderna-NIAID, or Johnson & Johnson may be used as a booster, regardless of which vaccine people received initially. 

Who Should Get a Booster? 

According to the CDC people 65 years and older, 50-64 with underlying medical conditions, or 18 years and older who live in long-term care settings should receive a booster shot. Also people 18 and older should receive a booster shot at least 2 months after receiving their Jonhson & Johnson/Janssen COVID-19 vaccine. 

Middle-aged and older adults with underlying medical conditions have a higher risk of severe illness if they contract an infection.

People living in a long-term care facility are at higher risk of coronavirus infection due to the close contact with many other people. Many of these people may also have chronic medical problems.

The CDC says other people who received an mRNA vaccine and are eligible for a booster may consider getting one, based on their personal risks and benefits.

Pfizer-BioNTech or Moderna COVID-19 Vaccine

  • Older adults age 65 and older. They should get a booster shot. The risk of severe illness from COVID-19 increases with age and can also increase for adults of any age with underlying conditions. 
  • Long-term care setting residentes ages 18 and older. They should get a booster shot because residents in this type of facility live closely together in group settings and are often older adults with underlying medical conditions. 
  • People 50-64 with underlying medical conditions. They should get a booster shot because the risk of severe illness increases with age and can increase for adults of any age with underlying medical conditions. 
  • People with underlying medical conditions 18-49. They may get a booster shot based on their individual risks and benefits. 
  • High risk settings ages 18-64. People with increased risk of exposure and transmission because of occupational or institutional setting may get a booster shot based on individual risks and benefits. Some examples are: 
    • First responders (healthcare workers, firefighters, police).
    • Education staff (teachers, support staff, daycare workers).
    • Food and agriculture workers. 
    • Public transit workers. 
    • Grocery store workers. 

J&J/Janssen COVID-19 Vaccine

People aged 18 years and older who received a J&J/Janssen COVID-19 vaccine at least 2 months ago should get a booster shot. The J&J/Janssen COVID-19 vaccine has lower vaccine effectiveness over time compared to mRNA COVID-19 vaccines (Pfizer-BioNTech and Moderna).

Here’s how to navigate the FDA’s regulatory decisions:

Why Do We Need Booster Shots, Are The Vaccines Working? 

COVID-19 vaccines are working well to prevent severe illness, hospitalization and death, even against the widely circulating Delta variant. However, public health experts are starting to see reduced protection, especially among certain populations, against mild and moderate disease. 

“People get confused—or they think something is wrong—when guidance changes with COVID-19, but we have to remember that we are learning about this as we go.”

— Albert Shaw, MD, PhD, Yale Medicine infectious diseases expert.

COVID-19 booster shots are not a new idea. Since the vaccines were first introduced last December, scientists have acknowledged that boosters may someday be needed.  

“The main question is how long the immunologic protection against SARS-CoV-2, which causes COVID-19, lasts,” says Albert Shaw, MD, PhD, a Yale Medicine infectious disease specialist. “And since we are learning about COVID-19 in real time, this is hard to know.” 

For now, Dr. Shaw emphasizes that the most important thing any of us can do is get vaccinated. And if you are already vaccinated, know that the situation is being closely monitored by the scientific and public health communities. 


Shawn Radcliffe (2021, Oct 25) COVID-19 Booster Shots: Should You Mix and Match? Healthline. Retrieved from:

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