Do I Need To Get A Booster Shot?

A third dose of a COVID-19 vaccine boosts the body's immune response, a Texas A&M expert says, giving added protection against Omicron and other variants.
By Caitlin Clark, Texas A&M University Division of Marketing & Communications December 7, 2021

hand wearing blue glove filling a syringe with vial of moderna covid vaccine
Booster shots are now recommended for all adults.

Getty Images


All adults are now recommended to get a COVID-19 booster vaccine, which health officials say will provide the strongest available protection against the virus as new variants emerge.

Even for those who have received their second dose of the Pfizer or Moderna vaccine, or the single Johnson & Johnson shot, “nobody’s fully vaccinated” at this point, said Ben Neuman, a virologist at Texas A&M University. He said booster doses are necessary to protect vaccinated people whose immunity has waned.

The COVID-19 vaccines currently available in the United States are still effective, he said – but at the time they were approved, it was unclear how many doses it would take to get “forever protection.”

“We’ve got good data that shows that antibodies drop off pretty steadily with each month after the second or first dose of the vaccine,” Neuman said. “By the time you are six months past your second dose, you’re actually only 50 percent protected.”

That’s enough protection to keep most people out of the hospital if they become sick, he said. But a third shot will bring a person’s immunity level back up, Neuman said, and because they started with a higher amount of antibodies, their protection can increase by 10 to 20 times.

“You’re taking good immune cells you already made, and the booster wakes them back up,” Neuman said. “Not only do they make more antibodies, but they’ll make antibodies similar to the ones that worked the best in the past, and can protect against strains of COVID-19 we haven’t seen yet.”

The Centers for Disease Control and Prevention’s new guidelines, last updated Nov. 29 after the emergence of the Omicron variant out of southern Africa, recommend boosters for adults who received their second dose of the Pfizer or Moderna vaccine at least six months ago or the Johnson & Johnson shot at least two months ago.

When getting the additional dose, the brand doesn’t matter, Neuman said. The CDC notes that while some people may choose to go with the vaccine brand they originally received, “mix-and-match” dosing for booster shots is OK.

Neuman said now is a good point for adults to get their additional dose, because it takes about 14 days to get the full benefits from a booster – which is just enough time to have extra immunity headed into the holidays.

“With almost all the vaccines we take, they’re actually more than two doses. The polio vaccine, for example, is four doses,” Neuman said. “So we don’t really know what full vaccination against COVID-19 looks like yet, except to say we’re probably not at it. We’re working our way toward it.”

COVID-19 boosters are now offered by Student Health Services at the A.P. Beutel Health Clinic. Students, faculty and staff can choose any of the available COVID-19 vaccines as a booster – each week the clinic may receive a different version of the booster shot, depending on vaccine availability. SHS recommends receiving the available booster shot as soon as possible.

Appointments can be scheduled online. Time slots are limited, but SHS will open more vaccination appointments as it receives vaccine shipments at the clinic.

Media contact: Caitlin Clark,

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