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VERIFY: How long are COVID-19 vaccines effective?

This summer will be a year since some of the first participants got the COVID-19 vaccines. We are still measuring the trials for effectiveness.

WASHINGTON — Why don’t we know for sure how long the COVID-19 vaccines are effective? It’s a question many people have asked since the country first began mass vaccinations in December 2020.

The time, right now, is at least six months. However, a viewer pointed out to the Verify Team, that the vaccine companies started giving people the vaccine in trials in the summer of 2020.


Why isn’t the length of effectiveness measured from that vaccine trial groups?


Dr. Aditi Nerurkar, a physician from the Harvard Medical School. Dr. Kawsar R. Talaat, an epidemiologist from Johns Hopkins University.


The time period of effectiveness is measured by the vaccine trial groups. The data collection is what takes time.


Our experts said it actually is the clinical trials that we use to measure the length of effectiveness.

“The phase three trial is the six-month data that we have to date after the second shot,” Dr. Nerurkar said. “It is the cohort of 44,000 people that are a part of that Pfizer trial.”

“Then you want to gather all the data from everybody in the trial, or as many people as possible from the trial at key milestones,” Dr. Talaat said.

At this point, all the approved data collected only stretches out for six months. But, these trial participants have milestones where they check-in. The next could be nine months or at a year.

While we look at the trial data, there may be even more reliable data coming soon.

“Since so many Americans have gotten vaccinated, we likely will have real-world data soon,” Dr. Nerurkar said.

To best sum it up, yes, some participants are approaching a year since they got their shots. However, the approved data from the trials take time to analyze and look at a wider group of people.

That is why we can only say at this point the vaccines are “at least” effective for 6 months.

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