On Friday, Oct. 15, outside advisors to the U.S. Food and Drug Administration (FDA) voted unanimously to recommend that regulators authorize a second booster shot of Johnson & Johnson's COVID-19 vaccine to better protect Americans who received the single-dose vaccine.

 

The FDA's Vaccines and Related Biologics Advisory Committee endorsed injections for all J&J recipients 18 years of age and older at least two months after their first dose. 

 

Here's what to keep in mind about booster doses of COVID-19 vaccines: 

The CDC indicates that booster doses should be given to people who have already been fully vaccinated at least 6 months earlier. 

 

Priority is given to persons ages 18-49 years old with underlying medical conditions and persons who are at increased risk for COVID-19 exposure and transmission due to their work or institutional setting, such as healthcare personnel. 

The CDC states that people with certain medical conditions are more likely to become seriously ill from COVID-19, making them eligible to receive a COVID-19 booster dose: 

The booster dose is important because the protection provided by the COVID-19 vaccines appears to decline over time, especially for people over 65 years of age or younger with severe illnesses. 

 

Several studies that looked at the overall effectiveness of the vaccines in various groups between February and August found similar patterns for the Pfizer and Moderna vaccines: effectiveness began to decline a few months after people were fully vaccinated, which is defined as two weeks after receiving their second dose of either vaccine.

Pfizer's FDA-reviewed data show that the booster vaccines do not appear to have different safety risks than the first two doses of vaccine. 

 

Pfizer's trials with the booster vaccines reported symptoms similar to those some people experienced after their first and second doses: temporary pain at the injection site, fever, chills, headache, fatigue, vomiting, diarrhea, and joint and muscle pain.

 

The same was found for the Moderna vaccine. 

Now that booster vaccines are available, the definition of "fully vaccinated" may change. Currently, people are considered fully vaccinated if they have received two doses of a Pfizer or Moderna vaccine, or a single dose of the J&J vaccine.   

 

"Over time, I anticipate that could be updated," CDC Director Dr. Rochelle Walensky said at a recent press conference on COVID-19. "But we'll leave that to our CDC Advisory Committee on Immunization Practices to come up with some recommendations."