How Often Do Those Who Get Vaccinated Spread Covid-19?


Director of the Centers for Disease Control and Prevention, Dr. According to Rochelle Walensky, the recommendation to get people in parts of the country vaccinated with powder from their masks was based largely on a troublesome finding.

In an email answering questions from The New York Times, he said the new research shows that vaccinated people infected with the Delta variant carry enormous amounts of the virus in their nose and throat.

The finding contradicts what scientists have observed in vaccinated people infected with previous versions of the virus, who often seem unable to infect others.

The result dealt a heavy blow to Americans: The so-called breakthrough infections of the Delta variant—the cases that do occur despite a full vaccine—can be just as contagious as unvaccinated people, even if they have no symptoms.

This means that fully vaccinated people with young children, aging parents, or friends and family with compromised immune systems, need to renew vigilance, especially in high-contamination communities. Vaccinated Americans may need to wear masks to protect not just themselves but everyone in their orbit.

As of Thursday, there are an average of 67,000 new cases per day in the United States. If vaccinated people transmit the Delta variant, they may be contributing to the increases, although possibly to a much lesser degree than unvaccinated people.

The CDC has yet to release its data, disappointing experts who want to understand the basis of the change of mind on masks. Four scientists familiar with the study said it was challenging, justifying the CDC’s recommendation that those vaccinated wear masks again in public indoors.

The scientists said the research was conducted by people outside of the CDC, and the agency is working quickly to analyze and publish the results. An official said the agency expects to publish the research on Friday.

Part of the research it may be partly related to an outbreak in Provincetown, Mass.The 4th of July festivities led to 882 cases on Thursday. About three-quarters of these people were fully vaccinated.

The agency also tracked data from the Covid-19 Sports and Society Working Group, a coalition of professional sports leagues that tests at least more than 10,000 people a day and ranks all infections.

It is still unclear how common the breakthrough infections are and how long the virus stays in the body in these cases. Dr. Breakthroughs are rare, and unvaccinated people account for a large proportion of viral transmission, Walensky said.

Regardless, the data the CDC has reviewed shows that even fully vaccinated people can be reluctant vectors for the virus. In an email to The Times, Dr. “We believe they may be on an individual level, so we’ve updated our recommendation,” Walensky said.

The result also suggests that vaccinated people who have been exposed to the virus should get tested even if they feel well. (In the UK, vaccinated persons who were contacts of a known case, necessary to isolate for 10 days.)

The new data does not mean that vaccines are ineffective. As intended, vaccines still strongly prevent serious illness and death, and people with breakthrough infections rarely go to the hospital.

According to data from the CDC, about 97 percent of people hospitalized with Covid-19 are unvaccinated. warned even last year that vaccines may not completely prevent infection or transmission. (Can offer immunity from natural infection even less protection.)

Previous versions of the virus rarely crossed the immunization barrier, which led the CDC to recommend in May: vaccinated people can go without a mask inside. However, the general rules do not seem to apply to the Delta variant.

The variant is twice as contagious as the original virus and a study He suggested that the amount of virus in unvaccinated persons infected with delta could be a thousand times greater than that seen in persons infected with the original version of the virus. An expert familiar with the results said CDC data support this finding.

Anecdotes of breakthrough infection clusters increasingly Frequently, with groups of vaccinated people reporting sniffling, headache, sore throat, or loss of taste or smell – signs of infection in the upper respiratory tract.

But the overwhelming majority do not need intensive medical care because the immune defenses produced by the vaccine destroy the virus before it reaches the lungs.

“We’re still going to see a huge, huge impact on disease severity and hospitalization,” said Michal Tal, an immunologist at Stanford University. “That’s actually what the vaccine is made to do.”

Coronavirus vaccines are injected intramuscularly, and the antibodies produced in response mostly stay in the blood. Some antibodies can the way to their nose, the main gateway of the virus, but not enough to prevent.

“Vaccines — they’re good, they work, they’re great,” said viral immunologist Frances Lund of the University of Alabama at Birmingham. “But they won’t give you that local immunity.”

When humans are exposed to any respiratory pathogen, they can find a foothold in the mucous lining of the nose without causing any harm beyond that. An epidemiologist at the London School of Hygiene and Tropical Medicine, Dr. “If you were walking down the street and swapping people, you would find people who had the virus on their mucous membranes and were asymptomatic,” said Michael Marks. “Our immune system mostly fights these things most of the time.”

But the Delta variant appears to develop in the nose, and its abundance may explain why more people are experiencing breakthrough infections and cold-like symptoms than scientists expected.

Still, when the virus tries to land in the lungs, immune cells in vaccinated people speed up and quickly clear the infection before it does too much damage. Dr. This means that vaccinated people need to be infected and contagious for a much shorter period of time than unvaccinated people, Lund said.

“But that doesn’t mean that once they’re infected in the first few days, they can’t infect someone else,” he added.

Some experts to stop the virus where it enters argued nasal spray vaccines that will prevent the invader from acquiring in the upper respiratory tract. “Vaccination 1.0 should prevent death and hospitalization. Vaccine 2.0 should prevent transmission,” said Dr. Tal. “We just need another iteration.”


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