Fauci Again Changes His Perspective on COVID-19 Herd Immunity Threshold

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, speaks during a White House coronavirus task force press briefing in the James Brady Press Briefing Room at the White House on Nov. 19, 2020. Tasos Katopodis/Getty Images

Dr. Anthony Fauci, director of the National Institute of Allergy and Infectious Diseases, has again changed his perspective on the COVID-19 herd immunity threshold in the United States, saying that his previous figures were “guesstimates.”

Fauci in an interview on Dec. 27 defended shifting his projections about herd immunity for COVID-19, the disease caused by the CCP (Chinese Communist Party) virus.

“We have to realize that we have to be humble and realize what we don’t know. These are pure estimates,” Fauci told CNN’s Dana Bash. “And the calculations that I made 70, 75 percent, it’s a range. The range is going to be somewhere between 70 and 85 percent.”

Herd immunity refers to when a population becomes immune to an infectious disease. Doctors say it will eventually be reached for all populations, and can be assisted by, but is not dependent upon, a vaccine.

Fauci last week told The New York Times that to achieve herd immunity against COVID-19, up to 90 percent of the population would need to be vaccinated, acknowledging that he had gradually increased his estimates from around 60 or 70 percent earlier in the year.

The nation’s top infectious disease expert is advising both President Donald Trump and Democratic presidential nominee Joe Biden on the CCP virus pandemic.

Fauci said Dec. 27 that his numbers were based on measles, not polling.

“Measles is about 98 percent effective vaccine [sic]. The COVID-19 vaccine is about 94, 95 percent,” Fauci said. “When you get below 90 percent of the population vaccinated with measles, you start seeing a breakthrough against the herd immunity, people starting to get infected, like we saw in the Upper New York state and in New York City with the Orthodox Jewish group, when we had measles outbreak.”

“So I made a calculation that COVID-19 is not as nearly as transmissible as measles. Measles is the most transmissible infection you can imagine,” Fauci said. “I would imagine that you would need something a little bit less than the 90 percent. That’s where I got to the 85.”

Fauci told Bash that although “nobody really knows for sure” what percentage of the U.S. population should be vaccinated to achieve COVID-19 herd immunity, 70 to 85 percent seems to be “a reasonable estimate.”

“In fact, most of my epidemiology colleagues agree with me,” he added.

“I want to encourage the people of the United States and globally to get vaccinated, because, as many as we possibly get vaccinated, we will get closer to herd immunity,” Fauci said. “So, the bottom line is, it’s a guesstimate. I gave a range. I use any discussion like we’re having now ... to encourage people to get to that goal of 70 to 85 percent of the people vaccinated. That’s where we really want to be.”

COVID-19 vaccines currently 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 to receive the vaccines first. Americans have been told that vaccinations for the general public will take six months or more to complete for logistical reasons.

Mimi Nguyen Ly contributed to this report.