How easy is it for vaccinated people to spread COVID-19?

The fear of a breakthrough COVID-19 infection has ruined the summer. In the early days of vaccine bliss, many Americans considered shots to be a ticket to normality. That’s exactly what public health professionals have been telling us, at least for some time. It’s COVID-19, but you don’t have to worry too much about spreading it to others. Interim guidance shared by the CDC in March states that these cases:Little risk of infectionA few weeks later, CDC director Rochelle Walensky said:Vaccinated people do not have the virus.. “

And then Delta came. The hyperinfectious subspecies surged cases and again filled the ICU with COVID patients. And it also spurred a complete freakout that all our understanding of who could spread the virus was wrong. CDC in early August The survey results have been released For a large cluster of COVID cases in Provincetown, Massachusetts, we conclude that 74% of cases occurred in vaccinated people.The possible implications of that discovery were even more ominous: those who were vaccinated Equally likely Spread the virus as unvaccinated. The CDC soon returned to recommend that vaccinated people wear masks indoors.People vaccinated against breakthrough infections can spread the delta variant, the CDC says... The worst-case scenario in which vaccinated people could live their lives just to disseminate large numbers of new coronavirus cases seemed suddenly possible.

Fortunately, three months later, we didn’t see this worst-case scenario come true. The fears raised by the Provincetown report were largely exaggerated. But that also does not mean that vaccination is clear.Breakthrough infections Still happening, And they can lead to infection. However, it is not yet known how widespread the spread is actually.

Read: No, vaccinated people are not as likely to spread the coronavirus as unvaccinated people.

Vaccinated people are less likely to spread the virus overall. Very unlikely to get infected in the first place.. CDC in early September found Six unvaccinated individuals were tested for COVID positivity on each vaccinated individual. But there are many reasons to be more optimistic.A few recently research Even after infection, vaccinated people are less likely to spread the coronavirus than unvaccinated people. “We are back in this category, Yeah, it can happen, but it seems like a very rare event“Los Keddle, a professor of immunology at the University of Colorado School of Medicine, told me.

He pointed me to two studies, neither of which was peer-reviewed. One shows that Infection occurred among vaccinated people in Provincetown, These cases represent what Kedl calls a “very limited” proportion of the total number of infections that have occurred as part of its outbreak.In another study, British researchers found Pfizer and AstraZeneca vaccines. Consistent reduction in infection downstream of breakthrough cases.. Many of Delta’s initial concerns were based on what is called “viral load,” the amount of virus that a person carries during an infection. However, the researchers concluded that viral load is only one of many factors associated with reduced infection. In other words, the same viral load in vaccinated and unvaccinated people does not necessarily mean that the virus is likely to spread.

One reason for this may be that vaccinated people carry less infectious viral particles, as in studies (not yet peer-reviewed). From the netherlands I explained recently. It is widely believed that the viral particles carried by vaccination and non-vaccination are the same, but the basic principles of immunology predict that they are not, Keddle told me. Viral particles excreted by vaccinated individuals are believed to be covered with antibodies. Produced in the nose and mouth Is considered part of “Mucosal” immunity— “Therefore, we can expect less downstream transmissions,” he said.

Other researchers have reached similar conclusions. Christopher Byronbrook, assistant professor at the University of Illinois at Urbana-Champaign, said, “The data make it very clear that vaccinated people are less likely to spread the virus to others than unvaccinated people. I’m doing it, “he said in an email.recently paper Brooke co-authored and showed that vaccinated people have less virus shedding, stop virus shedding faster than unvaccinated people, and shed less infectious particles. This supports the idea that it is unlikely to infect the disease. One study from the Netherlands We found that domestic infections in vaccinated people were reduced by 63%. This is proof of our vaccine. The house “is an environment where the decks are heavily piled up for transmission because the members of the household have been in close contact for a long time,” Brooke said. (But another recent study No statistically significant difference was found of home transmission Between vaccinated and unvaccinated people. Ultimately, Brooke can say that vaccinated people have a low risk of infection.

Read: Post-vaccination infections come in two different colors

So far, new research hasn’t rocked the CDC and needs attention. A spokesperson for the agency said that data from the Provincetown study has shown that fully vaccinated people with breakthrough infections can spread the virus to other people, including those who have been vaccinated. I told me by email that I was revealing it. Although science is still evolving, a spokesperson said, “At least early after infection, people who are fully vaccinated with a breakthrough infection are as infectious as those who are infected and unvaccinated, and others. It seems likely that it is a little less infectious to. “

Other public health professionals are also on the alert. “I don’t think there’s a jury yet on how vaccination reduces the risk of infection, but we know it will happen,” said Lisa Maragakis, senior director of infection prevention at John’s Hopkins Health System. I am. ” .. “I don’t say it’s low [risk].. She hinted at similar viral load data for vaccinated and unvaccinated people.

All the researchers I talked to agreed with one thing. Vaccination remains the best way to protect against infection and infection. Vaccines may not be perfect, but they are the best tool to protect yourself and others in the fight against COVID-19. In addition, vaccinated people can control the spread of the virus by avoiding situations where it is likely to occur. When it comes to breakthrough infections, “one of the things that hasn’t been fully discussed is behavior,” said Syra Madad, an epidemiologist at New York City Health Hospital. Events in Provincetown, including crowded indoor parties during the rise of the Delta, did not exactly help prevent breakthroughs. Precautionary measures such as masking and ventilation remain important. For these reasons, as holidays approach, Malagakis “monitors data in ways of concern.” Breakthrough infections increase and can spread as people begin to gather indoors.

Another wildcard is how long it has been since the vaccination. NS British papers, Protection against infection began to weaken after about 3 months, but most data show that overall protection is still very strong. For people under the age of 60, breakthrough infections can be disastrous for a week, but they rarely lead to hospitalization. Keddle told me that this age group is less likely to spread the virus, especially to other vaccinated people, because of its strong immunity. However, the same is not true for vaccinated people over the age of 65 who have a weak immune system and are vulnerable to serious illnesses and infections. Therefore, a booster shot is needed. According to Malagakis, the current “million-dollar question” is how often do you need it? booster In the coming months and years.

Read: Should You Mix Your Booster Shots?

There may not be consensus on how many infectious breakthrough infections there are, but that’s okay. Uncertainty is part of living with the coronavirus, even about 20 months after the pandemic. Unless we are confident, neglecting is the best way to keep the people around you safe. In short, “everyone infected needs to be quarantined,” Malagakiss said. “I am very hesitant to tell them that there is no danger of giving it to others.” Unfortunately, vaccination can safely carry out many activities, but 2019 You can’t behave like a year.

In the best scenario, getting a breakthrough infection is like getting the flu someday. “After all, the virus becomes endemic, so at some point everyone will be infected with the virus, regardless of vaccination status,” Brooke said. If a sufficient number of people are attacked and their immunity continues to be maintained, they may eventually panic about the consequences that vaccinated people may spread the virus. is not.