With a meteoric rise in deaths, talk of waves is misguided, say Covid-19 modelers

The numbers have become both horrifying and numbing — and there is no end in sight.

The consensus among major Covid-19 modelers is that we could see 20,000 to 25,000 deaths in just the next two weeks, and 160,000 more by Feb. 1. That would be a frightening acceleration as winter approaches.

The experts and their models also agree on the familiar tools at hand that can bend the curve: universal mask-wearing and social distancing. Even so, they say it’s too late for us to head off the surge ahead, as many Asian countries have been able to do.

“We may have passed the point of no return in terms of getting it to a place like levels we’re seeing in China right now,” said Nicholas Reich, a University of Massachusetts, Amherst, biostatistician whose team compares different Covid-19 models.

The meteoric rise in U.S. Covid-19 cases and death is not another wave. 

Experts modeling the coronavirus pandemic may differ on details, but they agree that calling this a second or third wave is incorrect because there was never a significant trough before cases began mounting again. 

The outbreak that slammed New York in the spring — as well as cities like Boston, New Orleans, and Detroit — was never brought under control, and instead it’s been allowed to keep building. 

Covid tracker screen cap 11/12/20
The STAT Covid-19 Tracker bears out what modelers say: There have not been significant troughs before cases have risen again.STAT

“I don’t think the United States ever had multiple waves,” said Alessandro Vespignani, professor of physics, computer science, and health science at Northeastern University in Boston who models the pandemic’s impact. “We are leading the same wave that is moving across the country.”

This is not 1918. Then, graphs show, there was a terrifying spike in influenza deaths followed by a flat line, when the epidemic almost went dormant in the summer before a monstrous second wave in the fall. Historical hindsight will have to tell what shape the Covid-19 story will ultimately take, but maybe future modelers will call them humps, Reich offered. Broadly speaking, the U.S. is heading toward a third hump while Europe is near its second. 

There’s a worrying parallel there, Reich said. “It’s just that humans are tiring of having to be so vigilant and it’s really exhausting — emotionally exhausting and socially exhausting.” 

The world’s health is in a very bad place, heading into winter in the Northern Hemisphere with Covid-19 cases, deaths, and hospitalizations all tallying new highs. That’s even before an expected spurt in all three metrics caused by colder weather and drier air, people spending much more time indoors, and overall weariness of lives disrupted by pandemic precautions — all of which make us more vulnerable to viruses. 

Trevor Bedford, a computational biologist at the Fred Hutchinson Cancer Research Institute in Seattle, reminded people taking comfort from an apparently lower death rate than earlier in the pandemic that deaths lag infections by about three weeks. “I expect the US to be reporting over 2000 deaths per day in 3 weeks time,” he tweeted Wednesday. That would be more than double the current numbers.

The U.S. as a whole has seen regional curves go up, dip, climb even higher, dip a bit less, and then ascend still higher to set new records nearly every day and every week. The geography of the pandemic is uneven, with ripples and bursts in the Sun Belt over the summer and infections jumping in the Midwest and Mountain states in the fall. But states in the Northeast that nearly buckled beneath the spring surge have no safe harbor from the continuing crisis. Cases and deaths have been ticking upward for weeks, as regular in their climb as a metronome.

Modelers make forecasts four weeks out, predicting cases and deaths. Separate models can be aggregated to yield an overall estimate of cases and deaths; some but not all include hospitalizations. The Centers for Disease Control and Prevention posts its ensemble forecasts, generated by Reich’s group at UMass from 36 independent models, for the country as a whole and for individual states. Models make assumptions about social distancing measures changing in the future or staying the same. 

Projections go farther than forecasts, but even they stretch only to Feb. 1, when warmer parts of the country might see crocus shoots poking through the soil in early signs of spring while winter is far from over in many states.

The model from the Institute for Health Metrics and Evaluation projects 399,162 total deaths in the U.S. by Feb. 1, based on current conditions. If mask wearing became universal, defined as worn by 95% of the population, deaths would fall to 337,669, the model says. But if mandates for social distancing were eased, the death toll would rise to 513,657.

February might be the earliest that the first vaccines become widely available, should they win approval. That means we are left with the tools and knowledge currently at hand to control spread this winter: pulling up our masks, tamping down numbers of people we gather with indoors (with optimal ventilation), getting our flu shots, and resisting the undertow of pandemic fatigue.

“The projections for this winter, unfortunately, they’re going to hold unless we change our behavior. The vaccine is not going to help us,” said Ali Mokdad, professor of health metrics sciences at IHME. “All we have between now and the vaccine deployment is wearing a mask, keeping a safe distance. I would like to remind everybody in the U.S. we’re not out of the woods yet.”

Mokdad calls for a national strategy that would set data standards and improve surveillance of cases and deaths so a coordinated response could be set into motion. 

Northeastern’s Vespignani also said the lack of a national strategy handicaps state efforts to fight the pandemic, especially when prompt reactions to rising cases can make a difference. Models that show climbing case counts, for example, should spur immediate measures before hospitals and their ICUs fill to overflowing two weeks later.

Coherent messaging would help, particularly in a time of White House transition. Any approved, successful vaccine will be a game changer, Vespignani said, but not anytime soon, so telling people what works now will be essential. “We need to enforce the use of masks and we need to have people act responsibly. We need to have a lot of testing and tracing in place,” he said. “And then the most important thing is that we don’t want to catch up with the epidemic. We want to anticipate it.” 

Lockdowns are not on Vespignani’s list. “It would be very depressing. It would mean that we didn’t learn anything in the first nine months of the epidemic.”

One lesson from the spring: Researchers who mined mobile phone data to identify the indoor public places most responsible for the spread of Covid-19 say that sharply limiting the occupancy of these locales — chiefly restaurants, gyms, cafes, hotels, and houses of worship — could help control the pandemic without resorting to lockdowns.

Modelers and policymakers alike struggle to find the sweet spot of doing just enough to keep the pandemic under control while keeping schools open, allowing people to work, and letting them go grocery shopping.

“One of the reasons that Covid-19 is so hard to predict is that the power to change the trajectory is within us,” Reich of UMass said. “If we all of a sudden decided to just be really careful about this for a sustained period of time, it would become under control — or at least become more under control.

“It is the societal challenge of our times.”

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