CDC Data Suggests Vaccinated Don’t Carry, Can’t Spread Virus

The good news keeps coming. Photo: Grant Hindsley/AFP via Getty Images

After warning for months that vaccinated people should still be cautious in order to not infect others, the Centers for Disease Control and Prevention suggests they may not be at much risk of transmitting the coronavirus.

“Vaccinated people do not carry the virus — they don’t get sick,” Dr. Rochelle Walensky, director of the CDC, told MSNBC’s Rachel Maddow on Tuesday. That’s “not just in the clinical trials, but it’s also in real-world data.”

Walensky was referring to a new CDC study that suggests those fully inoculated with the vaccines produced by Moderna and Pfizer don’t transmit the virus. Researchers looked at how the shots protected nearly 4,000 health-care workers, first responders, and other essential workers toiling in eight U.S. locations against the virus and more-contagious variants. Following a single dose of either vaccine, the participants’ risk of infection was reduced by 80 percent, and that figure jumped to 90 percent after the second dose. Without infection, people are unable to spread the virus. The results are similar to what scientists saw in clinical trials for the vaccines, which found that two doses of either two-dose vaccine had an efficacy rate of around 95 percent.

The study is the agency’s first to analyze how well the vaccines worked among working-age front-line adults, who are at a higher risk of being exposed to the virus and spreading it. “These findings should offer hope to the millions of Americans receiving COVID-19 vaccines each day and to those who will have the opportunity to roll up their sleeves and get vaccinated in the weeks ahead,” Dr. Rochelle Walensky, director of the CDC, said in a statement. “The authorized vaccines are the key tool that will help bring an end to this devastating pandemic.” Still, the CDC has not issued new guidance on how the vaccinated should behave; its current guidance is that they continue to take precautions such as masking.

Though the study is an impressive piece of evidence of the effectiveness of the Moderna and Pfizer vaccines, some public-health experts pushed back on Walensky’s pandemic-changing takeaway. “There cannot be any daylight between what the research shows — really impressive but incomplete protection — and how it is described,” Dr. Peter Bach, director of the Center for Health Policy and Outcomes at Memorial Sloan Kettering Cancer Center, told the New York Times on Thursday. “This opens the door to the skeptics who think the government is sugarcoating the science,” Bach added, “and completely undermines any remaining argument why people should keep wearing masks after being vaccinated.”

Even the Centers for Disease Control hedged on Walensky’s claims. “Dr. Walensky spoke broadly during this interview,” a CDC spokesperson told the Times. “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.”

More than 142 million doses of the Moderna and Pfizer vaccines have been administered in the U.S. as of March 30, according to the CDC. The third vaccine currently on the American market is a single-dose shot made by Johnson & Johnson, which was shown to be 66 percent effective in thwarting moderate to severe COVID-19-related illness.

This post has been updated to reflect a statement from the CDC provided to the New York Times.

CDC Data Suggests Vaccinated Don’t Carry, Can’t Spread Virus