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Here's what scientists currently know about how long protection lasts.

Karla Walsh
April 07, 2021
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"Get your flu shot!" is a familiar refrain each fall since the influenza virus continues to mutate, and scientists create a different flu shot every year to protect us from the most widespread regular flu virus that's expected to make waves.

We know that COVID-19 (AKA SARS-CoV-2) has already mutated. According to the Centers for Disease Control and Prevention (CDC), we now have at least five variants swirling around the U.S. So does that mean we'll need booster shots or yearly immunizations—or does a double dose of Pfizer or Moderna or single dose of the Johnson & Johnson vaccine cover us for good?

The scientific jury is still out, since all of the science related to this novel coronavirus is so, well, novel. But the messenger RNA (mRNA) technology used to develop the Moderna and Pfizer vaccines has been studied for years to create vaccines for other viruses, including Ebola, Zika and more common influenza strains.

"The antibody responses elicited by these mRNA vaccines are incredibly high. What we know in animal models with other mRNA vaccines that have been tested previously—we know that those antibody responses are incredibly long-lived and they don't drop over time," Scott Hensley, an immunologist and vaccine expert at the University of Pennsylvania tells CNN.

COVID-19 vaccine floating on designed background
Credit: Getty Images / bgblue - Pexel / rawpixel.com

The CDC studied nearly 4,000 vaccinated healthcare staff, first responders and frontline workers for a report they released on April 2. They found that those who were fully vaccinated, which is official 14 days after the final shot on the one- or two-shot program, were 90 percent less likely to get infected by the coronavirus. (Worth noting: Being fully vaccinated does not give you the green light to abandon all safety precautions. The CDC recommends that you still avoid large gatherings and wear a mask in public places like restaurants.)

Based on initial trials with the currently approved and in-use vaccines, it appears that this immunity lasts at least 6 months.

"The good news is that in the 6-month status report from Pfizer, immunity stays very strong, and we anticipate that it will continue to stay strong," Susan Bailey, M.D., an allergist and immunologist and president of the American Medical Association tells Healthline. "These people [in the study] have had the vaccine the longest, and it tells us it lasts at least 6 months...But it's definitely longer than that—it's not just going to drop off after 6 months."

Contrary to the pattern with the typical flu vaccine, several other vaccines (like the ones used for mumps, rubella and measles) last a lifetime, Bailey adds. "We don't know which camp the COVID-19 vaccine will fall into," she says.

But if a booster shot is required, it would likely be the result of variants rather than a dwindling impact of the first round of immunizations, per Bailey. It should be pretty seamless to produce with the same mRNA technology and trials are already underway.

Know someone who is on the fence about getting the coronavirus vaccine? Here are 5 things to keep in mind.