Early in the COVID-19 crisis, herd immunity, occurring when most of a population has immunity based on prior infection or vaccination, was considered a way out of the pandemic. Now, experts are saying such a threshold is unattainable, The New York Times reported May 3.
That's in part due to the arrival of more transmissible coronavirus variants and vaccine hesitancy, experts said. Early on, the general herd immunity target was 60 percent to 70 percent of the U.S. population. That threshold, however, continued to rise as more contagious variants began to spread. The estimated herd immunity threshold is now at least 80 percent, making it very unlikely.
"The virus is unlikely to go away," Rustom Antia, PhD, evolutionary biologist at Atlanta-based Emory University, told the Times. "But we want to do all we can to check that it's likely to become a mild infection."
Herd immunity is also likely unattainable because many parts of the world are far behind the U.S. in vaccinating their populations. In India, for example, less than 2 percent of the population has been fully vaccinated.
"We will not achieve herd immunity as a country or a state or even as a city until we have enough immunity in the population as a whole," Lauren Ancel Meyers, PhD, director of the COVID-19 modeling consortium at the University of Texas in Austin, told the Times.
Instead of herd immunity, the focus should be on ensuring the coronavirus remains manageable. That means keeping hospitalizations and deaths down, which is achievable with continued vaccination progress, experts said.
"What we want to do at the very least is get to a point where we have just really sporadic little flare-ups," said Carl Bergstrom, PhD, evolutionary biologist at the University of Washington in Seattle. "That would be a very sensible target in this country, where we have an excellent vaccine and the ability to deliver it," he told the news outlet.
To read the full New York Times article, click here.