Vaccinated people can carry as many viruses as others – .

Vaccinated people can carry as many viruses as others – .

In another disheartening setback for the nation’s efforts to eradicate the coronavirus, scientists who studied a large outbreak of COVID-19 in Massachusetts concluded that vaccinated people who contracted so-called breakthrough infections carried roughly the same amount of coronavirus than those who did not. shots.

Health officials released details of this research on Friday, which was key to the decision this week by the Centers for Disease Control and Prevention to recommend that vaccinated people again wear masks indoors in parts of the United States where the delta variant is fueling flare-ups of ‘infection. The authors said the results suggest the CDC’s mask guidelines should be expanded to include the whole country, even outside of hot spots.

The findings have the potential to upend past thinking about how the disease spreads. Previously, vaccinated people who were infected were believed to have low levels of the virus and were unlikely to pass it on to others. But the new data shows that is not the case with the delta variant.

The outbreak in Provincetown – a seaside resort spot on Cape Cod in the county with the highest vaccination rate in Massachusetts – has so far included more than 900 cases. About three-quarters of them were fully immunized people.

Travis Dagenais, who was among the many vaccinated infected, said that “putting caution to the wind” and partying in crowds for long nights during the July 4 holiday was a mistake in hindsight.

“The dominant public message has been that the vaccine means a return to normalcy,” the 35-year-old Boston resident said Thursday. “Unfortunately, I have now learned that it is a few steps towards normal, not the zero to sixty that we seem to have taken. “

Dagenais credits being vaccinated with relieving the worst of flu-like symptoms within days. He recovered.

Like many states, Massachusetts lifted all COVID-19 restrictions in late May, ahead of the traditional Memorial Day start of the summer season. Provincetown this week reinstated an indoor mask requirement for everyone.

Leaked internal documents on breakthrough infections and the delta variant suggest the CDC may consider other changes to advice on how the nation is fighting the coronavirus, such as recommending masks for everyone and demanding vaccines for doctors and other health workers.

The delta variant, first detected in India, causes infections more contagious than colds, flu, smallpox and Ebola virus, and it is as contagious as chickenpox, according to documents, which mentioned the Provincetown cases .

The documents were obtained by the Washington Post. As they note, COVID-19 vaccines are still very effective against the delta variant in preventing serious illness and death.

The Provincetown outbreak and the documents highlight the enormous challenge the CDC faces in encouraging vaccination while recognizing that revolutionary cases can arise and can be contagious but are rare.

The documents appear to be talking points that CDC staff can use with the public. One point advised: “Recognize that the war has changed,” an apparent reference to growing concern that several million people vaccinated could be a source of large-scale spread.

A spokeswoman for the agency declined to comment on the documents.

On Friday, the White House defended its approach to increasing cases of the virus and changing public health guidelines, repeatedly postponed to the CDC while stressing the need for vaccinations.

“The most important takeaway is actually quite simple. We need more people to get vaccinated, ”White House spokeswoman Karine Jean-Pierre said.

Pressed by the evolution of the orientations, Jean-Pierre repeated several times: “We do not take this type of decisions from here. “

People with breakthrough infections account for a growing share of hospitalizations and hospital deaths among COVID-19 patients, coinciding with the spread of the delta variant, according to the leaked documents.

While experts generally agree with the CDC’s revised position on indoor masking, some have said the Provincetown outbreak report does not prove that vaccinated people are a significant source of new infections.

“There is scientific plausibility for the (CDC) recommendation. But that’s not the result of this study, ”said Jennifer Nuzzo, public health researcher at Johns Hopkins University.

The CDC report is based on approximately 470 cases of COVID-19 linked to the Provincetown festivities, which included densely packed indoor and outdoor vacation events at bars, restaurants, guest houses and rental homes.

The researchers performed tests on a portion of them and found roughly the same level of virus in those who were fully vaccinated and those who were not.

Three quarters of the infections were in fully vaccinated individuals. Of those fully vaccinated, about 80% experienced symptoms, the most common being cough, headache, sore throat, muscle pain, and fever.

Dagenais said he started to feel bad the night he got home and initially attributed it to long nights of partying at crowded Provincetown nightclubs.

But as the days passed and the fever, chills, muscle aches and fatigue set in, he knew it was something more.

In the report, the measurement used by researchers to assess the amount of virus carried by an infected person does not indicate whether they actually pass the virus on to other people, said Dr. Angela Rasmussen, a virologist at the University of Saskatchewan.

CDC officials say more data is coming. They follow groundbreaking cases in much larger studies that involve following tens of thousands of vaccinated and unvaccinated people across the country over time.


The Associated Press’s Department of Health and Science receives support from the Department of Science Education at Howard Hughes Medical Institute. The AP is solely responsible for all content.


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