Dr. Anthony Fauci, head of the National Institute of Allergy and Infectious Diseases, said that to achieve herd immunity against COVID-19, 90 percent of the population would need to be vaccinated.
In an interview published Thursday, Fauci acknowledged that he had gradually increased his estimates from earlier in the year when he said that around 60 or 70 percent of the population would need to be vaccinated to achieve herd immunity.
Herd immunity is achieved when enough people in a population have immunity to an infection, whereby the chances of the disease being transmitted between people and reaching those who haven’t yet been infected is lowered, effectively preventing the disease from spreading.
“We need to have some humility here,” Fauci told the New York Times. “We really don’t know what the real number is. I think the real range is somewhere between 70 to 90 percent. But, I’m not going to say 90 percent.”
“When polls said only about half of all Americans would take a vaccine, I was saying herd immunity would take 70 to 75 percent,” Fauci told the outlet. “Then, when newer surveys said 60 percent or more would take it, I thought, ‘I can nudge this up a bit,’ so I went to 80, 85.’”
Previously, in an interview with CNBC News, Fauci gave an estimation of “between 75 and 80, 85 percent of the population” that needs to be inoculated for herd immunity.
“If we get that we would develop an umbrella of immunity. That would be able to protect even the vulnerables, who have not been vaccinated, or those in which the vaccine has not been effective,” he told CNBC.
“You can get that kind of immunity with that percentage of people, which is the reason why we’re being very enthusiastic in reaching out to the community to convince people of the importance of getting vaccinated, not only for their own safety, but for that of their family as well as for society in general.”
Health care workers, elderly nursing home residents, elected officials, and firefighters are among those receiving the vaccines first. Most Americans have been told it could be six months or more before they would be eligible for the shots.
The WHO changed the definition of herd immunity on Nov. 15, defining herd immunity as “a concept used for vaccination, in which a population can be protected from a certain virus if a threshold of vaccination is reached.” The organization now also states that “Herd immunity is achieved by protecting people from a virus, not by exposing them to it.”
The latest definition removes the WHO’s prior statement that herd immunity can be achieved through previous infection.
“What we know is, it is safe to be immunized after having been exposed to the virus. That has happened in the clinical trials. People that participated in the trials experienced or actually have a viral infection at the time that the trial started,” Operation Warp Speed’s chief scientific adviser Moncef Slaoui said on CNN’s “State of the Union.”
Operation Warp Speed is the Trump administration’s coordinated effort between federal agencies to speed up the development, production, and distribution of COVID-19 treatments.
Slaoui added, “So it’s safe. On the other hand, we know that infection doesn’t induce a very strong immune response, and it wanes over time. So as a clear precaution, it is appreciate to be vaccinated, because it’s safe, it will induce a much higher immune response, and will ensure, in case natural infection doesn’t induce long-lasting protection, it will allow to have better protection. I think people should be vaccinated, indeed.”
