Do you need a COVID-19 vaccine booster? What to know about booster shots

An announcement last week by pharmaceutical company Pfizer that it would seek approval to go forward with booster shots for those who have received the COVID-19 vaccine has left people wondering how protected they are against the coronavirus.

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The U.S. Food and Drug Administration, along with the Centers for Disease Control and Prevention, issued a joint statement following Pfizer’s announcement saying that those who are fully vaccinated with two doses of the Pfizer or Moderna shot, or one dose of the Johnson & Johnson vaccine, are well-protected against the virus and any variant (mutation) of it.

The statement said that at present, there is no plan to recommend a booster shot.

Officials from Pfizer are scheduled to meet Monday with federal health officials to explain why they feel the need to move forward with the request for a booster shot.

During that meeting, the discussion will likely include results from a study published in Nature that suggested that while the two doses of the Pfizer vaccine produced strong neutralizing antibodies against the Delta variant, a third dose would offer even greater protection from the virus’ mutation.

“The companies anticipate that a third dose will boost those antibody titers even higher,” said the Pfizer statement, announcing the company’s intention to ask for permission to give booster shots.

The Delta variant has become the dominant strain of COVID-19 in the United States, and states have begun to see a small number of breakthrough cases — or cases where a fully-vaccinated person contracts the COVID-19 virus.

In suggesting it will seek approval for a booster shot, Pfizer, along with its partner BioNTech, pointed to a study from Israel that the existing two-dose mRNA vaccine regimen provides less protection against infection for some COVID-19 variants, suggesting a booster shot may be needed for the variant.

On Monday, Israel began offering a third dose of the mRNA COVID-19 vaccine as a booster shot for people with weakened immune systems.

Here is what we know about the possible need for booster shots, how they work and who would need them.

Why do we need a booster shot for any vaccine?

A booster shot is another dose of a vaccine that is given to keep up the level of protection the original dose of the vaccine provides.

Booster shots are given because immunity, or the protection a vaccine offers the person who takes it, can decrease over time for some vaccines. For those vaccines, an additional “boost” of the vaccine is needed to keep up your body’s ability to fight off the infection.

An example of that is the measles vaccine. Children get two doses of measles vaccine, starting with the first dose at age 12 to 15 months of age, and the second dose between ages 4 and 6 years.

Will we need a COVID-19 booster shot?

So far, the has been no recommendation from federal authorities for anyone to get a booster shot after being fully vaccinated with a COVID-19 vaccine.

Dr. Amesh Adalja, a senior scholar at Johns Hopkins Center for Health Security in Baltimore, told Healthline that it is still too early to predict whether COVID-19 boosters will be needed.

“To me, the threshold for boosters would be to see fully vaccinated individuals getting breakthrough infection severe enough to land them in the hospital,” Adalja told Healthline. “We have not crossed that threshold.”

Another consideration would be if the virus mutates enough to make current vaccines less effective.

Ali Ellebedy, an immunologist at Washington University in St. Louis who co-authored the new Nature study, told Vox that he could see everyone needing a booster if a variant becomes particularly strong.

“But if we control the variants, then maybe we don’t need it for all of us, but we need it for that special population” who are immunocompromised or elderly, Ellebedy said.

Dr. Ashish Jha, the dean of Brown University’s School of Public Health, said Friday that he sees no evidence now that a booster shot would be needed.

“Let me tell you where we are: the data is very clear, if you’ve gotten your two shots of Moderna or Pfizer or (a) single shot of J & J (Johnson & Johnson), you have a very high level of protection against all variants, including Delta,” Jha said. “I have not seen any evidence, so far, that anybody needs a third shot.”

How will I know if I need the booster?

Again, it is too early to tell if a booster would be needed, but if it is, the CDC and other federal authorities would alert the public as to who needs a booster shot.

You would be more likely to need a booster if you are older, or if your immune system is compromised by a disease or an organ transplant.

If a booster is needed, how would distribution work?

If it is determined that booster shots are needed, it is likely they would be disturbed the way the COVID-19 vaccines were — with the most vulnerable at the front of the line, according to Krutika Kuppalli, an infectious disease expert at the Medical University of South Carolina.

“I think you will have to have a targeted approach toward how you roll them out due to a supply/demand consideration,” Kuppalli told Vox. “I would envision rolling them out to those who are most immunocompromised first, like transplant recipients and cancer patients.”

Would a booster shot have to match the vaccine I got?

According to Dr. William Petri, professor of medicine, University of Virginia, it probably would not have to match.

Petri wrote in The Conversation, “Recent research has shown that mRNA vaccines, like Pfizer and Moderna, can be mixed with adenovirus-based vaccines like AstraZeneca with comparable results.”