Even with Covid-19 cases on the rise due to the omicron subvariant BA.5, hospitalizations and deaths have remained largely stable, leading some health experts to suggest that the pandemic may be reaching a "steady state" that could characterize the country's next few years.
Has Covid-19 reached a steady state in the US?
Since the omicron variant became dominant in the United States, Covid-19 cases have skyrocketed, with roughly half of all infections during the pandemic occurring this year alone. Currently, CDC data shows that there have been almost 900,000 new Covid-19 cases over the last seven days, largely driven by the highly contagious BA.5 omicron subvariant.
However, even as cases continue to rise rapidly, hospitalizations and deaths have remained largely stable, with increases occurring in a relatively narrow range. Overall, the pandemic may have reached "something like a steady state" over the past few months, David Wallace-Wells writes for the New York Times.
According to Trevor Bedford, a computational virologist at the Fred Hutchinson Cancer Center, the United States may have entered its "endemic phase" with Covid-19. Although some epidemiologists would argue against using the term "endemic" for technical reasons, Bedford noted that conditions have now shifted notably from earlier phases of the pandemic and are unlikely to change over the next few years.
"If we're saying that we're still in a pandemic right now, it's still going to be a pandemic in year seven— we'll still be in a pandemic then," Bedford said. "So I think it's better to acknowledge that we're at 98 percent of the population having immunity of some form—certainly over 95 percent. There's not much more that could change in that regard."
What endemicity could look like under BA.5 conditions
Around 5% of the U.S. population is currently being infected by the coronavirus each month, according to Bedford, and he expects this pattern to continue for some time. As an estimate, this means that under endemic conditions around 50% of Americans will be infected every year, and more than 100,000 will die.
However, Céline Gounder, an infectious disease epidemiologist and a senior fellow at the Kaiser Family Foundation, said that figure is likely the low end for Covid-19's annual mortality, estimating that deaths will reach between 100,000 and 250,000 overall.
If these estimates are accurate, Covid-19 would be one of the leading causes of deaths in the United States for several years, beating out diabetes, pneumonia, and kidney disease, Wallace-Wells writes.
"That steady state doesn't put us in a great place," said Natalie Dean, a biostatistician who specializes in the epidemiology of infectious disease at Emory University.
The 'long, bumpy off-ramp' toward Covid-19's future
Currently, the United States is on a "long, bumpy off-ramp" to a more manageable future with the coronavirus, according to Michael Mina, an epidemiologist and chief scientist at eMed.
"We are not seeing the same levels of death," Mina said. "We're just not. And that's really important because this is reflecting not just the fact that we have treatments but a combination of immunity from infections and vaccines."
Against the coronavirus, humans as a species are roughly immunologically equivalent to 2- or 3-year-olds, according to Mina. This means that although we have passed "the real risk zone" and are able to navigate living with the coronavirus, there is still a potential risk for infection and severe illness.
"We know that 3-year-olds still go to the hospital a lot, but we know that given the same infections, 3-year-olds do a lot better than 1-year-olds," he said. "And that's because of immunity."
Over time, as people get more infections, vaccinations, and boosters, immunity will increase and provide more rigorous protection. "Eventually, it will settle out, and then our immune histories will really protect us more and more and more each year," Mina said.
However, what is less clear is how the coronavirus will continue to mutate over the next few years and how that will affect people's immunity. According to Katia Koelle, an evolutionary virologist at Emory University, the coronavirus could continue to mutate to evade immunity for a "very, very long" time.
To bypass immunity, "a virus only has to be different than it was previously," Koelle said.
So far, the rate of the coronavirus's mutations throughout the pandemic has largely been what experts have expected. "We knew from relatively early on that we would expect about two mutations a month," said Francois Balloux, a computational biologist at University College of London. "That means that we would have expected, after two and a half years, roughly 70 mutations. And actually that's where we are."
What has been surprising, though, according to Balloux, is how significantly some of these mutations have changed the virus—first with delta and then later most substantially with omicron. For example, between delta and omicron, there was such a shift in the pandemic's trajectory that Balloux said he was "tempted to think about it in terms of two successive pandemics."
"What that means for the future, it's really difficult to say," he said. "We can have a radical new shift, like we saw with Omicron—something completely, radically different jumping into a population. And then we're back at square one." (Wallace-Wells, New York Times, 7/20; Wu, The Atlantic, 7/14)