About 73% Of US Estimated To Be Immune To Omicron Variant

By Carolyn Crist

About 73% of Americans are now immune to the Omicron variant, which could increase to 80% by mid-March, a university health institute says.

About half of eligible Americans have received booster shots, and about 80 million confirmed COVID-19 infections have been reported. Many more infections have occurred but haven't been officially recorded.

The high percentage of immunity from vaccination and previous infection tends to prevent or shorten new illnesses and reduce the amount of virus circulating overall. Health experts are now discussing whether the number is high enough to stop new waves or reduce the burden on hospitals.

"I am optimistic even if we have a surge in summer, cases will go up, but hospitalizations and deaths will not," said Ali Mokdad, PhD, a professor of health metrics sciences at the University of Washington in Seattle.

Mokdad works on COVID-19 forecasting for the university's Institute for Health Metrics and Evaluation, which has been a reliable model during the pandemic. Mokdad calculated the 73% number.

"We have changed," he said. "We have been exposed to this virus and we know how to deal with it."

The U.S. is now reporting about 125,000 new cases per day, marking a 68% decrease from the past 2 weeks. Hospitalizations are also down 39%, and about 2,300 new deaths are being reported daily, marking a 13% decline.

There will be more outbreaks as new variants emerge, immunity wanes, and some people remain unvaccinated, Mokdad said. But the coronavirus is no longer new, and the entire population is no longer "immunologically naive." Scientists are now trying to understand how long booster protection will last against Omicron and how many people have been infected who had mild or no symptoms that were never reported.

By the end of the Omicron surge, about three out of four people in the U.S. will have been infected, said Shaun Truelove, PhD, an epidemiologist and disease modeler at Johns Hopkins University.

"We know it's a huge proportion of the population," he said. "This varies a lot by location, and in some areas, we expect the number infected to be closer to one in two."

That means different regions and groups of people have different levels of protection and risk. In Virginia, for instance, disease modelers estimate that about 45% of residents have the highest level of immunity by being vaccinated and boosted or vaccinated with a recent Omicron infection. Another 47% have immunity that has waned somewhat.

"That's going to be a nice shield of armor for our population as a whole," Bryan Lewis, PhD, an epidemiologist who leads the University of Virginia's COVID-19 modeling team, told the outlet. "If we do get to very low case rates, we certainly can ease back on some of these restrictions."

About 7% of Virginians are considered the most vulnerable because they were never vaccinated or infected, he noted. Nationwide, about 80 million Americans are still vulnerable.

"The 26% who could still get Omicron right now have to be very careful," Mokdad said.

The percentages will continue to change as immunity wanes and new variants circulate in the country. For now, the Institute for Health Metrics and Evaluation model estimates that about 63% to 81% of Americans are protected.

"We've reached a much better position for the coming months, but with waning immunity, we shouldn't take it for granted," Mokdad said.

Share this