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.’”
Fauci is advising both President Donald Trump and Democratic presidential nominee Joe Biden on the CCP (Chinese Communist) Party virus pandemic.
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.”
COVID-19 vaccines available in the United States are those from Pfizer-BioNTech and Moderna. More than 1 million Americans—or about 0.3 percent of the U.S. population—have received a first dose of a vaccine since Dec. 14, according to the Centers for Disease Control.
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 World Health Organization recently changed its definition of “herd immunity.” Previously, on June 9, 2020, the WHO defined the term as “the indirect protection from an infectious disease that happens when a population is immune either through vaccination or immunity developed through previous infection.”
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.
A WHO official, Dr. Soumya Swaminathan, said in August, “With a vaccine you can achieve immunity and herd immunity safely. Through natural infection, we could also achieve it at some point, but it would be at great human cost. And so naturally, the better choice is doing it through a vaccine.”
Moncef Slaoui, chief scientific adviser for the Trump administration’s Operation Warp Speed, said on Dec. 20 that Americans should get vaccinated for COVID-19 even if they were already infected with the disease.
“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.”
New CDC data shows that most people who were vaccinated didn’t experience negative effects. But the data also showed that thousands of people have been unable to work or perform daily activities, or they have needed care from a health care professional, after getting a new COVID-19 vaccine.
At least five health care workers in Alaska experienced adverse reactions after getting the Pfizer-BioNTech vaccine, the Anchorage Daily News reported. One worker at the Bartlett Regional Hospital required treatment at the hospital for at least two nights.
An Illinois hospital halted vaccinations after four workers suffered adverse reactions.
Zachary Stieber and Reuters contributed to this report.