Is the worst over? Modelers predict steady decline in COVID cases through March

Americans may soon breathe a sigh of relief, according to researchers studying the trajectory of the pandemic.

The delta surge appears to be peaking nationwide, and cases and deaths will likely decline steadily until spring without a significant winter surge, according to a new analysis shared with NPR by a consortium of researchers advising the Centers for Disease Control and Prevention.

For its latest update, which it will release on Wednesday, the COVID-19 Scenario Modeling Hub has combined nine different mathematical models from different research groups to get a perspective on the pandemic for the next six months.

“All of us who have been following this closely, given what has happened with delta, are going to be very cautious of being overly optimistic,” says Justin Lessler of the University of North Carolina , which helps to manage the hub. “But I think the trajectory is towards improvement for most of the country,” he said.

The modelers developed four potential scenarios, taking into account the take-off or not of childhood vaccinations and the emergence of a new, more infectious variant.

The most likely scenario, Lessler says, is that children get vaccinated and no variant of super spread emerges. In this case, the combined model predicts that new infections would slowly, but fairly continuously, drop from around 140,000 today to around 9,000 per day by March.

Deaths from COVID-19 would drop from around 1,500 per day now to less than 100 per day by March 2022.

This is roughly the level at which cases and deaths in the United States were at the end of March 2020 when the pandemic just started to break out in the United States and better than things seemed at the start of the year. summer, when many believed the pandemic was waning.

And that scenario predicts that there won’t be a winter push, although Lessler cautions that there is uncertainty in the models and that a “moderate” push is still theoretically possible.

There is a wide range of uncertainties in the models, he notes, and it is plausible, though highly unlikely, that cases can continue to rise to 232,000 per day before they start to decline.

“We have to be careful because the virus has shown us time and time again that new variants or people slacking off on their caution can turn things around,” Lessler warns.

William Hanage, an epidemiologist at the TH Chan School of Public Health at Harvard, notes that there is a fair amount of uncertainty in the models. “I would be worried if I interpreted them too optimistically for the country as a whole,” he said.

He agrees that overall the pandemic will be “comparatively under control by March”, but says “there could be a number of bumps in the road”.

Last winter, the worst outbreak of the pandemic in the United States hit the middle of winter when the weather was cold and more people were spending time indoors. “If you look at the seasonal dynamics of coronaviruses, they typically peak in early January. And in fact, last year we saw a peak like SARS-CoV-2, ”he says.

Hanage and Lessler both note that there will be regional variations, with some states continuing to increase for perhaps a few weeks. Basically, things could get even worse in some places before they get better.

Lessler says he’s particularly worried about Pennsylvania, for example, and he notes that in some western states like Idaho and Utah, there is a risk of a resurgence. Hanage notes that places with a cold winter may be subject to some increase in cases later in the year.

And hospitals are going to continue to be inundated with patients for some time before infections abate, and many are already being pushed past breaking point.

Another caveat: This scenario assumes that the United States is not affected by a new variant that is even more contagious than the delta. If so, a darker scenario from the Modeling Hub predicts much worse numbers: just below 50,000 cases per day by next March. But Lessler points out that this is very hypothetical.

He hopes the most optimistic scenario is the most likely.

“I think a lot of people tend to think that with this surge it will never get better. And so maybe I have to stop worrying about it and take risks. But I think those projections are us. show there a light at the end of the tunnel, ”he said.

Lessler believes that at this point there is enough immunity in this country thanks to a combination of enough people who have been vaccinated and enough people who have been exposed to the virus.

“The biggest driver is immunity,” he explains. “We saw really big delta waves. The virus ate sensitive people. So there are fewer people to infect.” The virus is still fighting, he says, but “immunity always wins out.”

But transmission is still very high and will remain so for some time, so care should be taken until new infections drop to moderate levels.

Natalie Dean, assistant professor of biostatistics at Emory University, notes that while we may see a drop this fall, we will still see “a lot of cases and deaths.”

Vaccinating all eligible people is always the key to preventing further deaths. Even in this optimistic scenario, the United States is expected to reach a cumulative total of over 780,000 deaths by March.

Modeling is an imprecise science, but the Modeling Hub brings together many of the country’s top disease modellers, doing their best to look far down the road and make sense of a very unpredictable and complicated pandemic that has started a curve after l ‘other.

“I hope that’s true, obviously, but I can’t help but feel a little uneasy about what could happen,” Dean said.

So, like many Americans, Dean is keeping his fingers crossed.

Copyright NPR 2021.