Omicron's increased transmissibility has led to record numbers of coronavirus infections, bolstering immunity to help blunt future surges—but many health experts still warn of trouble going forward due to the potential for new variants and waning immunity over time.

The omicron scenario planning guide: 7 situations health care leaders must address

Could omicron's infectiousness help with future surges?

An estimated 86.2% of Americans had been exposed to the coronavirus, whether through vaccination or previous infection, by the end of October 2021, The Atlantic reports. Now, as omicron rapidly spreads across the country—adding around 800,000 confirmed new Covid-19 cases each day—the number of people who are immunologically naïve to the virus is quickly shrinking.

According to Virginia Pitzer, an epidemiologist at the Yale School of Public Health, around 90% to 95% of all Americans will have some form of immunity against the coronavirus after the current omicron surge subsides.

"Few people will be naïve—completely naïve, no protection from either vaccination or natural infection—when the omicron wave is over," said Cecile Viboud, an infectious diseases epidemiologist and modeler at the NIH's Fogarty International Center.

According to some health experts, this increase in overall population immunity could help Covid-19 become more manageable during future surges and variants.

Hans Kluge, director of the World Health Organization's (WHO) European region, said, while it's too early for countries to drop their guards completely, "[o]micron offers plausible hope for stabilization and normalization."

Kluge added that the pandemic is "far from over," but he is, "hopeful we can end the emergency phase in 2022 and address other health threats that urgently require our attention."

Separately, Scott Hensley, a vaccines researcher at the Institute for Immunology at the University of Pennsylvania, said that a decrease in viral transmission after the omicron wave could reduce the risk of new variants. "None of us think the virus is going to go away, but the virus will have less opportunity to change because there will be fewer hosts that it can replicate in," he said. "And in an immune population, due to immunity, disease severity will be less."

There's likely still trouble past omicron, experts warn

However, other experts warned that there is still potential for new, more dangerous variants to evolve.

WHO director-general Tedros Adhanom Ghebreyesus on Monday warned that new future variants are likely. Tedros said, "It's dangerous to assume that [o]micron will be the last variant or that we are in the endgame … On the contrary, globally, the conditions are ideal for more variants to emerge."

Kluge agreed, saying it is "almost a given that new Covid-19 variants will emerge and return," and that, "[t]his pandemic, like all other pandemics before it, will end, but it is far too early to relax."

According to Deepta Bhattacharya, an immunologist at the University of Arizona, omicron is "not a derivative of delta and so that's what makes it a little unpredictable as to what [variant is] going to come next."

Adam Kucharski, an associate professor of infectious diseases epidemiology at the London School of Hygiene and Tropical Medicine, agreed, noting that the unusual evolution of the coronavirus variants has made the future path of the virus difficult to predict.

"I think people have this idea that omicron's the endgame. Anything that emerges [next] is going to emerge from omicron, and then we're into this low level, perhaps slightly seasonal endemic state," Kurcharski said. "But, given what we've seen previously, I think we have to be aware that there's some uncertainty around that."

In addition to potential new variants, protection against infection from both virus- and vaccine-induced immunity wanes over time, which means many people who are well-protected now will be vulnerable again in a few months. (Protection against severe disease, on the other hand, appears so far to be more robust.)

Different areas of the country will also not have the same level of immunity, according to The Atlantic, particularly as vaccination rates remain low in rural areas, poor communities, and low-resource communities. There are still plenty of "pockets that may have not yet had exposure to vaccination or the virus," said Bertha Hidalgo, an epidemiologist at the University of Alabama at Birmingham. This means that areas with comparatively less immunity will be hit harder by any future outbreaks of the coronavirus.

"Some people will be left with immune houses of straw, others of wood, others of brick," said Anne Sosin, a health equity researcher at Dartmouth University.

Overall, even after the omicron wave passes, future surges of the coronavirus will likely still be problematic in their own ways, The Atlantic reports. Instead of a nationwide surge in cases, surges may be more local, making them harder to track, or even more asynchronous, as they start and stop at different times in different areas. (Wu, The Atlantic, 1/21; Branswell, STAT News, 1/19; Santora, New York Times, 1/24)