The predictions ranged, but some of the warnings were stark: 100 million Americans could be infected with COVID-19 in what would be a massive fall and winter surge. Ultimately, though, the U.S. ended up with its first winter of the pandemic without a large wave of coronavirus.
“This winter there was no major surge similar to what we have seen before,” says Ali Mokdad, an epidemiologist with the Institute for Health Metrics and Evaluation at the University of Washington. “No major increase in hospitalization or mortality. And that’s true across the Northern Hemisphere, where winter is what we expect from now on as we will have a seasonal increase in COVID-19.”
It wasn’t a surge, but there was still an increase in COVID-19 over the winter. The weekly average of COVID-19 hospitalizations peaked in January at over 41,000, according to data from the Centers for Disease Control and Prevention. It’s more than three times smaller than the surge last winter, when the U.S. saw the highest ever number of weekly COVID-19 hospitalizations at more than 146,000.
While hundreds of Americans are still dying from the coronavirus each day, it’s significantly fewer fatalities than the past two winters, which saw thousands of daily deaths. Weekly COVID-19 deaths reached nearly 4,500 in January. Last winter, weekly deaths peaked at over 17,000 in February 2022. The highest ever weekly death count came the winter before that, with more than 23,000 reported in January 2021.
So what caused the drop-off in numbers? The main driver was the high level of COVID-19 immunity in the population, according to experts.
The vast majority of Americans have some level of immunity against COVID-19 through infection or vaccination or both. While immunity levels wane over time, research shows that protection against severe disease and death lasts substantially longer than protection against infection.
Cartoons on the Coronavirus
“The fact that the original omicron surge a year ago was so big and so many people got infected has given a certain level of immunity to the population,” says Shishi Luo, head of infectious diseases for Helix, a company that supplies viral sequencing information to the CDC. “How long that protection lasts is unclear, but it certainly would have helped with the most recent winter.”
Another contributing factor: the lack of another Greek letter variant. New omicron subvariants seem to emerge and take over every few months, but as they say, the devil you know is better than the devil you don’t.
Since omicron first emerged and fueled the major coronavirus surge last winter, the U.S. has run through several iterations of the variant: BA.2, BA.4, BA.5, BQ.1.1, BQ.1 and most recently XBB.1.5. The subvariants came with concerns like high immune escape capabilities and rendered some COVID-19 treatments useless.
But an entirely new Greek letter variant has the potential to be much more harmful. In the worst-case scenario, it could cause more severe disease, resulting in more hospitalizations and deaths. Or it could make protection provided by the COVID-19 vaccines and previous infection ineffective, dialing back population immunity levels to near zero.
“As long as the variants continue to descend from omicron, this type of wave would be the expected pattern,” says Luo. “No one really knows what would happen if something other than omicron were to emerge.”
Experts underscored that surveillance of COVID-19 and how it’s changing is of the utmost importance because it could offer a heads-up if a problematic new variant comes down the line.
One factor that could have played a role in preventing illness on the individual level but likely not across the entire population was people’s behavior. While many Americans have moved on from the COVID-19 pandemic, some are still paying attention to the headlines.
According to a recent survey from Kaiser Family Foundation, 46% of adults said news of the “tripledemic” – the spread of COVID-19, flu and respiratory syncytial virus, or RSV – made them more likely to take at least one protective measure, like wearing a mask in public or avoiding large gatherings. Adults aged 65 and older were significantly more likely than younger adults to take at least one mitigation measure over the winter. Underscoring the partisan divide that has defined much of the pandemic, the survey found that Democrats were more than twice as likely as Republicans to say the tripledemic this winter made them more likely to take at least one precautionary measure.
Additionally, experts generally agreed that the updated COVID-19 booster shots were likely not a major reason for keeping a large winter surge at bay. Too few Americans – just 16% of the population – took the shot, they said. One reason for the shot’s low uptake is likely how many people have already been infected with the virus, according to Mokdad.
“Too many people did not get the fourth or fifth dose – depending on where they are – simply because they got infected by omicron,” he says.
But experts underscored the shot’s efficacy and the protection it provided on the individual level this fall and winter.
“I don’t think it would have impacted the dynamics, but I think it was important that it was available for people who are at high risk of severe illness to have that as a form of protection,” Luo says.
Looking forward, it’s unclear what this winter without a major COVID-19 wave means for future winters. Experts are hopeful that it could be the first of many, but there are concerns that it could make Americans complacent and fuel an increase once immunity levels have waned.
The Biden administration is eyeing a switch to an annual COVID-19 booster shot that would be offered in the fall similar to the flu shot. But Mokdad is concerned that because the winter didn’t see a major surge and the majority of Americans didn’t take the updated booster shot, their incorrect takeaway message from this winter is that they are safe without another vaccine.
“The message for many people next year is to shy away from the vaccine,” Mokdad says. So public health officials, he says, have a major challenge ahead of them to encourage more Americans to get a booster shot next time around.