How long to Covid-19 vaccine boosters last? CDC study finds booster effectiveness drops with time

A new study from the Centers for Disease Control and Prevention shows when COVID-19 vaccine booster effectiveness begins to drop.

"The study in the U.S. looked at a large number of people, the Vision Network, and I think it was ten states worth of data," said Dr. Matthew Sims, the director of Infectious Disease Research at Beaumont Health. "It looks like, according to the study, at about four months you start to wane in your protection."

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The findings show that vaccine effectiveness against Covid-related emergency room and urgent care visits plus hospital stays was higher after the third dose than after the second dose but decrease over time.

Doctors say that the results show that as the virus evolves and produces variants, the vaccine needs to change also.

"Over time the vaccine will evolve and the omicron specific vaccine I think will be necessary," Sims said.

More: Will we need more boosters or a new shot?

The recent CDC report also shows that a booster dose of the Pfizer and the Moderna vaccines still offer high levels of protection against severe Covid-19 despite the fact that protection can decrease over time.

Doctors are still urging people to get vaccinated.

"Once we know the cycle we will have a better idea where we’re going, but everyone has to remember we’re early in this, but it’s killed millions of people, and we’re just trying to prevent it from killing more," Sims said.