A year after Covid-19, 2 factors are critical to making it through 2021

In February 2020 the world first began to see early news articles detailing a strange novel coronavirus circulating in China. It was the start of our first winter living with a pandemic.

As we near our second winter of Covid-19, scientists are starting to predict what February 2021 might look like. With such predictions, comes a question wrought by months of pandemic fatigue: Will this winter be anything like the last?

Last week, scientists at the University of Washington’s Institute for Health Metrics and Evaluation (IHME) released their predictions for the United States. The team projects that by February 28, 2021, 511, 373 lives could be lost. That’s an additional 285,634 deaths beyond the current total in the U.S., as of this article’s publication.

The paper was published Friday in the journal Nature Medicine.

That death toll assumes that states will reinstate social distancing mandates (which may include school closures, restrictions on gatherings, stay-at-home orders, or the closure of non-essential businesses) when deaths surpass 8 per million — 90 percent of the threshold at which these measures were instituted last winter.

Speaking to reporters on Friday, lead author Christopher Murray, a health economist, said he expected the current fall surge to pick up steam. The U.S. set a single-day record for new coronavirus cases last Friday – reporting more than 85,000 new cases that day.

“We think the key point here is that there’s a huge winter surge coming,” Murray said during a Friday press conference.

Murray's model uses cellphone data to approximate adherence to social distancing – a far from perfect measure. It also relies on historical death totals from last year. That was before scientists had made any strides in developing treatments for Covid-19, or understood how the illness affected the heart, lungs, stomach, and immune system.

The paper also estimates that 129,574 lives could be saved if 95 percent of people wore masks and the U.S. reinstates social distancing measures – two things the U.S. was slow to do last year that could make all the difference this time around.

Winter 2021 forecast

There are a number of factors that working for us this time around. Critically, emerging evidence suggests doctors are getting better at treating the coronavirus, as a paper published by a different team on Friday, this time in the Journal of Hospital Medicine, suggests.

Of 5,000 patients admitted to NYU Langone hospital over 16 weeks, the team found that mortality among patients dropped from 30 percent for those admitted in the first two weeks to three percent among those admitted in the last two weeks. But the median age of those admitted had decreased from 69 to 47, and there were fewer male patients (more likely to die), or patients with underlying conditions.

That suggested it was a change in demographics, not treatments that explained the drop.

But they also found an average of an 18 percentage point drop in mortality among all groups, suggesting that changing demographics didn’t tell the whole story. This could suggest doctors are getting better at treating coronavirus.

Speaking to reporters in reference to his own study, Murray acknowledged this trend could be real. (His team has also been looking for signs we are better at treating the virus but hasn’t detected significant trends in their own work.)

As a consequence, the IHME model doesn’t take the idea that we’re getting better at treating the virus into account. This model could change if our new understanding of the virus alters our course.

“To date, it’s been much harder to find that effect that everyone thinks is happening than one would have thought of," Murray says. "We’ve been studying this for about 6 weeks and we have not yet found an effect, but it doesn’t mean there hasn’t been [one]."

Masks will also give us a powerful tool that we didn’t have last year. The U.S. did not begin advocating for mask-wearing by the general public until April.

In the scenario envisioning a universal adoption of mask-wearing, the model predicts that 129,574 lives could be saved. The universal scenario means that 95 percent of people wear masks when they go outside, all the time. If only 85 percent of people wore masks, 95,814 lives could be saved.

The scenario where those 511,373 lives are lost happens if only 49 percent of Americans wear masks in public. But on the IHME website, week-to-week projections are made assuming that about 69 percent of people are wearing masks. The 49 percent figure used in the paper likely is outdated and the newer data collected by IHME suggests we're closer to that 69 percent threshold.

Even in that scenario, we fall short of the universal mask threshold. Still, the team notes that any “any additional coverage that can be achieved through mask use will save lives.”

Because of that, Murray calls masks an “easy win.”

Masks can also, in turn, delay the return to stricter social distancing measures, an additional benefit. In the best case scenarios, masks push back the time we have before stringent social distancing measures are reimposed.

In the universal masking scenario, nine states would reach the threshold during at we would expect to see stringent social distancing measures reimposed by the end of February: California, Colorado, Massachusetts, New Jersey, New Mexico, North Carolina, North Dakota, Pennsylvania, and Rhode Island. If mask use continues at the rate used in the paper, 45 states would reach that threshold by the end of February.

While that may seem like masks can prevent a return to more extreme social distancing measures in some places, Murray said the eventual return to them is unpreventable. It’s a question of when they’re reimposed, not if they’re reimposed.

“I think it’s very difficult at the point where we are in the US, where there’s so much community transmission of the virus to prevent some fall-winter surge," he said. "But we can certainly make it much smaller."

What we can control is how many lives are lost before that happens. If governments impose stricter measures at the right time, and people both comply and wear masks, about 130,000 people may be saved.

Abstract: We use COVID-19 case and mortality data from 1 February 2020 to 21 September 2020 and a deterministic SEIR (susceptible, exposed, infectious and recovered) compartmental framework to model possible trajectories of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infections and the effects of non-pharmaceutical interventions in the United States at the state level from 22 September 2020 through 28 February 2021. Using this SEIR model, and projections of critical driving covariates (pneumonia seasonality, mobility, testing rates and mask use per capita), we assessed scenarios of social distancing mandates and levels of mask use. Projections of current non-pharmaceutical intervention strategies by state—with social distancing mandates reinstated when a threshold of 8 deaths per million population is exceeded (reference scenario)—suggest that, cumulatively, 511,373 (469,578–578,347) lives could be lost to COVID-19 across the United States by 28 February 2021. We find that achieving universal mask use (95% mask use in public) could be sufficient to ameliorate the worst effects of epidemic resurgences in many states. Universal mask use could save an additional 129,574 (85,284–170,867) lives from September 22, 2020 through the end of February 2021, or an additional 95,814 (60,731–133,077) lives assuming a lesser adoption of mask wearing (85%), when compared to the reference scenario.