In atoday in the MMWR, scientists at the U.S. Centers for Disease Control (CDC) report more good news from real-world . In the study involving 3,950 healthcare workers, first responders, and other essential workers vaccinated between December 2020 and March 2021, the researchers found that the two-dose vaccines are 90% effective in protecting people from getting infected SARS-CoV-2, the virus behind COVID-19. A single from infection.
The people in thewith one of the first two authorized shots from Pfizer-BioNTech and Moderna, which both require two doses and rely on mRNA technology. In the studies both companies provided to the U.S. Food and Drug Administration to earn emergency use authorization, the shots were 94% to 95% . The studies didn’t show whether from getting infected with the virus in the first place. These new, real-world findings show that the against infection, a critical extra layer of protection since infected people can spread the disease to others, even if they don’t experience any symptoms.
In the MMWR study, CDC scientists found that two weeks after getting both doses, people in the trial were nearly fully protected against gettingcompared to people who weren’t vaccinated. The study teased this apart by asking each participant to take weekly by swabbing their noses. Most of the positive tests occurred in people who had no symptoms when they were tested and did not even know they were infected. The fact that the are 90% effective in protecting people from infection is an essential benefit of the shots. But, say, experts, the encouraging news doesn’t mean that . And that’s because of new variants of the virus that have emerged that the vaccines were not to target. The study didn’t show whether , with one of the variants now circulating worldwide.
That means that people don’t need to wear a mask because I’m not at risk of infection,’” says Dr. Paul Offit, director of the vaccine education center at the of Philadelphia and member of the FDA advisory committee that reviews vaccines. “The problem with that is the variants. You can still get sick if you are exposed to a variant, and you can still shed and spread the virus.”or Moderna shots can still get infected and sick if infected with one of these variants, albeit not as severely ill as they might have if they hadn’t gotten the shots. In addition, they could also still pass along the variant virus to others. “People may interpret these results as meaning, ‘Great, now that I’m vaccinated, I
Plus, whileare much less likely to get infected and, therefore, much less likely to spread the virus, it’s still not entirely clear that they are not contagious if they do happen to get infected. “Until there is a lot less , I will continue wearing a mask,” says Dr. Carlos , professor of medicine at Emory University, who has been vaccinated. “The protection against infection wasn’t perfect—80% to 90%. Can I increase that to closer to 100% by wearing a mask? Yes.”
To document whether vaccinated people are less contagious, the National Institute of Allergy and Infectious Diseases launched a study in March to follow 12,000from 21 universities and their close contacts. Half of the students will be vaccinated immediately, with the other half vaccinated four . All participants will provide detailed information about their close contacts, including roommates, classmates, and teammates, and swab their noses for the presence of SARS-CoV-2. Researchers will follow up with anyone with a by pushing the close contacts of these individuals to see if they, too, became infected. By comparing infection rates among the touches of those the virus.
Those results will take about six months, and until then, the CDC is still recommending that even people who are fully vaccinated can only drop their masks if they are indoors with other people who are fully immunized in. In the meantime, “I hope people don’t misinterpret this study,” says Offit. He’s concerned that since a single was 80% effective in protecting against infection, people might skip the recommended second dose. That would be a bad idea, he says, because “It is clear, crystal clear, that you need the second dose to produce adequate T-cell immunity,” which is the more durable and that will help people to mount robust immune responses to not just the original virus but to different variants as well.
“T-cell immunity provides cross-protection against variants; if you don’t have T-cells, you are much less likely to be protected against the variants. These results may push some people to get just one dose.” Instead, the findings should make more people comfortable about theand even help to loosen current CDC social-distancing restrictions. “Hopefully, this study will be perceived as even stronger evidence that you can’t get infected if you’ve been vaccinated, and at the end of the day, people want to hear that,” says Del Rio.