Joe Raedle/Getty Health-care worker receives COVID-19 vaccine
The Centers for Disease Control are walking back claims made by its director that people who are vaccinated against COVID-19 do not spread the virus, clarifying that they do not yet definitively know if that's the case.
CDC Director Dr. Rochelle P. Walensky had said Tuesday that "vaccinated people do not carry the virus, don't get sick, and that is not just in the clinical trials but it's also in real world data." Her statement was based on a large study the federal health agency released Monday that had tracked newly vaccinated people in the U.S. over 13 weeks to monitor the efficacy of the vaccines in daily life. The CDC followed nearly 4,000 heath care workers, police, firefighters and other essential workers who received one of the two mRNA vaccines between Dec. 14 and March 13 and tested them weekly for COVID-19.
Testing showed that the risk of infection went down by 90% two weeks or more after they received their second dose, and even just one dose was 80% effective after two weeks. Of the 2,479 people in the study who were fully vaccinated, just three contracted COVID-19, which is in line with the vaccine's efficacy. In comparison, the CDC also tracked 994 people who were not vaccinated, and 161 contracted COVID-19. No one in the study died.
Because the majority of the vaccinated people did not test positive for COVID-19 during the 13 weeks, Walensky concluded that they did not carry the virus.
But after scientists criticized Walensky's comments this week, the CDC walked back her statement.
"Dr. Walensky spoke broadly during this interview," an agency spokesman told The New York Times on Thursday. "It's possible that some people who are fully vaccinated could get COVID-19. The evidence isn't clear whether they can spread the virus to others. We are continuing to evaluate the evidence."
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After Walensky's comments, health experts also emphasized that the CDC study does not mean that vaccinated people can stop wearing masks. There is still a risk that they could get COVID-19 as the vaccines are not 100% effective, especially with several faster-spreading variants now circulating through the U.S. that are more resistant to the vaccines.
"We can kind of almost see the end," Walensky said on The Rachel Maddow Show on Tuesday. "We're vaccinating so fast … And yet on the other side, I'm watching the cases tick up. I'm watching us have increased numbers of hyper-transmissible variants. I'm watching our travel numbers tick up, and the sense is, I have seen what it looks like to anticipate the oncoming surge. And what I really would hate to have happen is to have another oncoming surge just as we're reaching towards getting so many more people vaccinated."
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