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COVID booster protection wanes after 4 months, says CDC

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Posted at 3:08 PM, Feb 14, 2022
and last updated 2022-02-14 18:00:47-05

HAMPTON ROADS, Va. - The numbers are encouraging - the University of Virginia's COVID modeling says 34 out of 35 health districts in the Commonwealth seeing continually declines in COVID cases this month.

But, something else is also declining - your booster shot effectiveness.

It is called waning immunity, and a new study out says your booster may lose effectiveness after a few months.

The U.S. Centers for Disease Control and Prevention's (CDC) study, published Friday, looked at Pfizer and Moderna vaccines across 10 states from late August through the end of January this year. The study found the vaccines were more potent when the Delta variant accounted for majority of the cases than Omicron did.

"These vaccines are safe; they have been on the market in use for quite a while. We continue to see no concerns with them in terms of safety," said Marshall Vogt, Senior Epidemiologist at the Virginia Department of Health (VDH).

But if you just got your booster, may it may lose effectiveness in a few months, says Vogt.

"Waning immunity is when your immune system and your body's antibodies after a vaccine start to decrease levels of those circulating antibodies," he said.

The CDC's most recent study found third shots, or boosters, become less likely to protect against serious illness after about four months.

"Even though there is reduced effectiveness in vaccine series with the booster over time, it's highly effective preventing severe illness and keeping you out of the hospital. That’s the biggest takeaway," said Vogt.

The study also found protection faded more in preventing trips to the doctor or emergency departments, falling from 87% in the first two months to 66% after four months. After more than five months, vaccine effectiveness fell to roughly 31%.

"It not only protects you, but other people. If you are vaccinated, you are less likely to shed as much virus as long of period of time, and it reduces strain on our healthcare and medical system," he said.

The CDC recommends all eligible people remain up to date on vaccines, especially those whose immune systems may not be as strong.

"Immunity tends to wane faster in people that are older. Their immune systems are not as robust, and the same for those that are immunocompromised," he said.

Click here for our full COVID vaccination guide.