Millions of individual Americans’ immune systems now recognize the virus and are ready to fight it if they encounter the omicron, or even another variant.
About half of eligible Americans have received boosters, there have been nearly 80 million confirmed infections overall, and many more infections have never been reported. An influential model uses these and other factors to estimate that 73% of Americans are, for now, immune to omicron, the dominant variant, and that this could rise to 80% by mid-March.
This will prevent or shorten new illnesses in those protected and reduce the amount of virus circulating overall, likely dampening new waves. Hospitals will get a break from overwhelmed intensive care units, experts agree.
“We have changed,” said Ali Mokdad, a science professor of health metrics at the University of Washington in Seattle. “We have been exposed to this virus and we know how to deal with it.”
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The coronavirus – the current variant or the future ones that are sure to appear – remains a dangerous germ. It still infects more than 130,000 Americans and kills more than 2,000 every day. Tens of millions of people remain vulnerable.
And there will be future epidemics. The notion of a “herd immunity” that could stop the virus has escaped under the stark reality of new variants, waning immunity and the rejection of vaccines by some Americans.
But the coronavirus is no longer new. Two years ago, he arrived in a country where no one’s immune system had seen him before. The entire population – 330 million people – was immunologically naïve, that is, susceptible to infection.
“I am optimistic even if we have an increase in the summer, cases will increase, but not hospitalizations and deaths,” said Mokdad, who works on the model from the Institute for Health Metrics and Evaluation, which calculated the figure. 73% for The Associated Press.
With varying degrees of relief and caution, many Americans are beginning to return to their pre-pandemic lifestyles.
Sarah Rixen, 41, of Bismarck, North Dakota, returned to singing with a civic choir after taking a year off. Now, with omicron over, she said she feels more confident than at any time since the crisis began.
“But I’m still a little suspicious that there might be another variant around the corner,” Rixen said, noting that her family and most of her relatives are fully vaccinated. “I will always wear a mask.”
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As mask mandates ease, workers return to offices and flights fill up, experts are trying to figure out if this return to normal can last, or if another setback looms.
To address this issue, researchers are trying to answer questions about the virus, the vaccine, and how our bodies respond: How quickly does booster protection wane against omicron? How long does protection against infection last? How many mild infections have never been reported? How many people have been infected but have shown no symptoms?
To find clues, they’re using health data from other countries like Britain, Denmark, South Africa and Qatar to project what might be in store.
Scientists at Johns Hopkins University Bloomberg School of Public Health estimate that about three out of four people in the United States will have been infected with omicron by the end of the outbreak.
“We know that’s a huge proportion of the population,” said Shaun Truelove, epidemiologist and disease modeler at Johns Hopkins. “It varies a lot by location, and in some areas we expect the number of people infected to be closer to one in two.”
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This means that different regions or groups of people have a different level of protection – and risk. In Virginia, disease modelers think of their population in terms of groups with different levels of immunity.
They estimate that about 45% of Virginians have the highest level of immunity from either boosted vaccination or vaccination plus recent omicron infection. Another 47% have somewhat diminished immunity; and 7% are most vulnerable because they have never been vaccinated and never infected.
In total, the vast majority of Virginians have at least some immunity, said Bryan Lewis, a computational epidemiologist who leads the University of Virginia’s COVID-19 modeling team.
“It’s going to be great armor for our population as a whole,” Lewis said. “If we get to very low case rates, we can certainly loosen some of those restrictions.”
Yet, while the population is better protected, many individuals are not. Even according to the most optimistic estimates of population immunity, about 80 million Americans are still vulnerable. That’s about the same as the total number of confirmed infections in the United States during the pandemic.
“The 26% who might still get omicron right now have to be very careful,” Mokdad said.
Andrew Pekosz, a virus researcher at the Johns Hopkins Bloomberg School of Public Health, worries that people — especially unvaccinated omicron survivors — have a false sense of security. “In an ideal world, unvaccinated people infected with omicron would line up for a vaccine,” he said.
Moreover, estimating protection is far from an exact science. It’s a moving target, as immunity wanes and new variants circulate. Protection varies greatly from person to person. And it is impossible to know for sure how many people are protected. The IHME model estimates a wide range – from 63% to 81% of Americans.
“We have reached a much better position for the coming months, but with waning immunity, we shouldn’t take it for granted,” Mokdad said.
AP writer Dave Kolpack in Fargo, North Dakota, contributed.
The Associated Press Health and Science Department is supported by the Howard Hughes Medical Institute Department of Science Education. The AP is solely responsible for all content.
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