As more people shift activities indoors with dropping temperatures across much of the country, health experts are concerned about a potential rise in flu and COVID-19 cases this coming winter.
In each of the last two winters, COVID cases and hospitalizations have dramatically spiked in the state of Illinois, with last winter seeing the switch from the delta variant to the more contagious omicron variant that has since spawned even more contagious subvariants now making up a majority of cases.
This winter, experts are also concerned about a potential sharp rise in flu cases, with a growing expectation that flu cases will rise to pre-pandemic levels.
"I would be shocked if this year we didn't have the worst flu season that we've had while COVID has been with us and I don't know for sure what that will look like," Arwady said, noting that "flu season has not kicked off in any serious way yet here in Chicago, thankfully."
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NBC News reported in August that flu was surging in Australia, marking a shift for the country since the start of the pandemic and potentially pointing to signs of what's to come for the U.S. As of Aug. 4, the country was reporting its worst flu season in five years.
"The Southern Hemisphere is our best predictor of what the Northern Hemisphere is going to look like for flu season and respiratory season because the seasons are backwards," Arwady said. "So if I want to know what our winter might look like in terms of flu, the best place to look is the Southern Hemisphere's winter - our summer - and Australia has had a terrible flu season that they are just, you know, coming out of now. Chile, some other countries in the Southern Hemisphere have had bad flu seasons."
And with COVID guidelines now easing even further, experts say that could bring the return of other respiratory viruses.
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"Unless behavior changes and people go back to mask-wearing, we will see a lot more of all of these respiratory viruses," said Dr. Sharon Welbel, the director of Hospital Epidemiology and Infection Control for Cook County Health. "We're already seeing some influenza."
As for another COVID wave this year, the seasonal shift has marked dramatic changes each year of the pandemic so far. As a third winter approaches, however, experts are on edge for what could happen -- and there's one early sign they're watching.
While there remains optimism this year thanks to new COVID booster shots specifically designed to target omicron and its dominant subvariants, scientists are already eyeing small changes in variant proportions so far this fall.
Chicago Department of Public Health Commissioner Dr. Allison Arwady has warned that if uptake on the new booster shots is slow, then the city could potentially face a third consecutive year of surging cases.
"I would be the happiest person alive if we get to February or March and we've seen nothing happen or very little happen on the COVID front, we've seen a very mild flu season," Arwady said Tuesday. "I would really feel more confident that we are even more past COVID as a society, whereas right now, I love that we're at a low COVID level - we should be celebrating that, thank you Chicago, but... I am, appropriately I think based on what we've learned about COVID, a little concerned about what we may see this fall and winter."
In the fall of 2020, COVID cases spiked to record-levels, with hospitals pushed to their breaking point by the influx of new cases through late November.
In 2021, things were even worse thanks to the onset of the omicron variant of COVID, with Illinois averaging nearly 33,000 new cases of coronavirus per day during the worse surge of the pandemic.
This year, officials are hoping that new treatment options and vaccinations will help prevent a similar surge. The FDA and CDC have both authorized new COVID vaccine boosters that were specifically formulated to fight back against omicron variants of the disease, and the wide availability of antivirals like Paxlovid have also given doctors hope that any increases in cases could potentially be turned back.
Though Arwady notes that there remain fears of a new variant emerging that could change that projection.
“The thing I worry about isn’t about whether a surge comes with omicron, but if we don’t get a lot of uptake of the updated vaccine, and we continue to see a lot of mutation, and we have a variant emerge that is really different from anything we’ve seen previously,” she said last month. “That’s what happened last December and January.”
As of Tuesday, the BA.5 omicron subvariant, which has been the dominant strain of COVID-19 in the United States for more than three months, was still responsible for four-in-five cases of the virus, but its grip is beginning to loosen as two other variants gain steam.
According to the latest figures from the CDC, BA.5 is responsible for an estimated 81.3% of COVID cases in the United States, down from 83.2% a week ago.
The BA.5 subvariant rose to prominence at the same time as the BA.4 subvariant, but it’s a descendant of BA.4 that is growing most quickly in the U.S. According to CDC estimates, BA.4.6 is responsible for 12.8% of cases this week, up from just under 12% a week ago.
The BF.7 subvariant, a descendant of BA.5, is responsible for 3.4%, according to CDC estimates.
Like other evolutions of the COVID virus, new spike proteins on both BA.4.6 and BF.7 are helping the virus to better evade both natural immunity conferred from previous iterations of omicron and immunity gained by vaccination, even with new boosters on the market.
It remains unclear whether those new bivalent boosters, which are specially-formulated to help fight back against severe illness from omicron, will protect against infection in general, with studies still underway even as Americans begin to get the shots.
In addition to a potential COVID surge, experts are warning of what could be a particularly challenging flu season.
