Facebook posts – Study did not find that vaccines prolong contagiousness of COVID-19

A new study has not proven that getting the COVID-19 vaccine can keep you contagious longer if you are infected with the virus compared to not getting vaccinated.

But a social media post argued otherwise. An August 18 YouTube video shared on Facebook claimed that a new study had found that vaccinated people were “5 times more infectious than the unvaccinated 10 days after SARS-CoV-2 infection.”

SARS-CoV-2 is the novel coronavirus that causes COVID-19.

The video host posted a screenshot of a New England Journal of Medicine study, which he said determined that “individuals fully vaccinated and boosted against COVID-19 appear to recover significantly slower. of the disease and, surprisingly, even remain contagious for longer periods of time. compared to the unvaccinated.

The post was flagged as part of Facebook’s efforts to combat fake news and misinformation on its News Feed. (Learn more about our partnership with Facebook.)

(Screenshot from YouTube.)

The video identified a study by Massachusetts researchers affiliated with Brigham and Women’s Hospital, Massachusetts General Hospital and the Ragon Institute, which studies immunology. The New England Journal of Medicine published the study on July 21.

From July 2021 to January 2022, researchers asked 66 people with “newly diagnosed” COVID-19 to provide additional nasal swab samples three times a week for two weeks – or until tested. negative for COVID-19 with a PCR test.

The researchers studied people infected with the delta or omicron BA.1 variant. Sixteen participants were unvaccinated, 37 were vaccinated, and 13 were vaccinated and received a booster.

One of the study’s co-authors, Dr. Amy Barczak, an infectious disease specialist at Massachusetts General Hospital, said the study aimed to examine how long people infected with delta or variants of the coronavirus omicron shed detectable virus.

Despite the video’s claims, the study did not find that people who were vaccinated against COVID-19 remained infectious longer or recovered more slowly than people who were not vaccinated against the disease.

“There would be no way to make that calculation from our data,” Barczak said.

In fact, the study reported no difference between vaccinated and unvaccinated patients in how long it took for a PCR test to change from positive to negative or how long it took to a culture test or growth attempt. live virus in culture from a nasal swab, to pass to the negative.

A study assessed how long a person would shed an infectious virus

Barczak said the main finding of the study was that people infected with the delta or omicron variant shed the virus and are therefore potentially infectious for a median of six to eight days from the onset of symptoms or illness. a positive SARS-CoV-2 test. Some people remained potentially infectious for up to 10 days.

In December 2021, the Centers for Disease Control and Prevention recommended shortening the isolation period for people infected with COVID-19 in non-health care settings from 10 days to five days.

The study results are important, Barzack said, “because they have implications for when one should self-isolate after developing SARS-CoV-2 to avoid infecting others.”

The researchers cautioned that the results were limited by the small sample size of 66 COVID-19 cases.

Our decision

A video shared on Facebook claimed that a study had found that vaccinated people were “5 times more infectious than unvaccinated people 10 days after SARS-CoV-2 infection”.

The study in question found that people infected with the virus shedding the delta or omicron variant of COVID-19 and were potentially infectious for a median of six to eight days – and up to 10 days – after the onset of symptoms or their initial positive PCR test.

It also reported no difference between vaccinated and unvaccinated patients in the time it takes for a PCR or viral culture test to go from positive to negative.

We assess these claims as false.

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