As COVID-19 vaccination rates decline and variants become more pervasive, scientists and public health experts say the threshold needed to reach “herd immunity” is not likely any time soon — and we may never get there, according to a report from the New York Times.
With millions of Americans being vaccinated against COVID-19 every day — more than 105 million fully vaccinated as of Sunday — many are looking to the future and asking when the coronavirus pandemic will end. It’s a surprisingly difficult question that could hinge on the epidemiological concept of herd immunity.
Cindy A. Prins, Ph.D., M.P.H., a University of Florida Health infectious disease epidemiologist who is an associate professor in the UF College of Public Health and Health Professions and the UF College of Medicine, explained that herd immunity means that enough people have immunity to an illness that even if one person gets infected within the group, it’s not going to easily spread to other people because of that immunity.
Prins said the threshold for herd immunity is still not clear.
“You’ll see estimates upwards of about 70% of a population needing to reach immunity through either vaccination or infection before herd immunity is achieved. And then you’ll see estimates that go even higher, more toward 90%. It’s one of those things that we’re gaining a better understanding of along the way,” Prins said.
Experts worry vaccine hesitancy could stand in the way of reaching herd immunity.
“What I really worry about is that those people who are already on the fence don’t get vaccinated (and) we don’t reach herd immunity come the fall,” CNN medical analyst Dr. Leana Wen told CNN.
Dr. Anthony Fauci, the chief medical advisor to President Joe Biden, estimates between 70% to 85% of the US population needs to be immune to the virus to control its spread.
Experts told The Times that it’s likely that the coronavirus will evolve into a manageable threat that still results in hospitalizations and deaths but in lower numbers than have been seen in the last year.
According to data from the CDC, more than 44% of the population has received at least one vaccine dose and more than 31% is fully vaccinated.
But one expert said that most people will be able to get back to their pre-pandemic lives if case numbers continue to fall.
“We may not get to zero, we probably won’t,” Dr. Ashish Jha, dean of the Brown University School of Health, told CNN on Monday. “But if we can get the infections at very low levels, most of us can get back to our lives in normal ways. I think we can probably live with that.”