Will you need a Covid-19 booster? 

Is a booster shot for your COVID-19 vaccine in your future? While it seems like only yesterday that people were calculating the date they could feel fully protected by their vaccination, now there’s talk that our safety may require another shot in the arm. 

What is a booster: The simplest answer is that it’s just another dose of a vaccine you received,” Dr. Shaw explains. “The concept is to prolong protective immunity, particularly if there is evidence that protection is waning after a period of time.”

Most children receive routine vaccinations, including boosters, for illnesses such as chickenpox, tetanus, diphtheria, mumps, measles, and rubella—to name a few. “These vaccine series, as we call them, are recommended because you need the extra doses to get longer lasting protective immunity,” Dr. Shaw says.

There is also a technical distinction between the terms “third dose” and “booster.”  

Doctors use the term third dose when referring to people with compromised immune systems who may not have gotten the level of protection they need from the first two doses. The third dose provides that level of immunity.

A booster shot is recommended due to concern that the effectiveness of the vaccine decreases over time and may not protect against a new strain, such as Delta. A booster may be given to older people or those with chronic medical conditions or other risk factors.

Why might we need a booster for COVID-19?

While a booster sometimes is an exact replica of the initial vaccine, it can also be tweaked. With COVID-19, this is key because the vaccine could then be tailored to target particular variants of the virus.  

“The current vaccines are still effective against the variants we are now seeing, particularly for protecting against serious illness that would require hospitalization or cause death. But if the virus evolves further and there is a worse variant, the vaccine could be modified,” Dr. Shaw says. 

One of the great things about the mRNA technology, which the Pfizer and Moderna vaccines use, Dr. Shaw notes, is that it’s easy to change them up to match variants, and they can be quickly produced at scale. “This is different from the manufacturing process for the most commonly used flu vaccines, which is a much slower process because influenza virus strains need to be grown in chicken eggs, from which a particular viral protein is purified and formulated into a vaccine,” he says. 

But what about the Johnson & Johnson vaccine? In September, Johnson & Johnson released data about a booster to its original one-dose vaccine, saying a second dose given two months after the first increased protection against COVID-19 to 94% and that it increases antibody levels by four to six times compared to one dose alone. 

The FDA has reportedly not yet received an application for a J&J booster, but it is reviewing data from Moderna for a booster to its vaccine. 

yalemedicine