What Will Cold and Flu Season Mean for the Coronavirus Pandemic?

There is the possibility of becoming infected first with a cold or flu, which weakens the respiratory system, and then with sars-CoV-2.

The other day, as I was driving across the Brooklyn Bridge, the brakes of my car, a twenty-one-year-old Toyota, stopped working. I pressed the pedal. The car kept rolling. I was going slowly enough that I didn’t hit anyone, or anything, but the feeling was nauseating. The emergency brake, thankfully, still worked, and I inched into Manhattan with my hazards on. Afterward, as I sat in the car, safely parked behind City Hall but shaking with fear, it struck me that the incident was a bit too on the nose, too appropriate, for this moment. The public-health system that should have slowed the pandemic has failed. Now, as flu season arrives, the uncertain course of the coronavirus in the U.S. can feel like a queasy ride toward further disaster. What will the crucible of winter hold?

In September, the official death toll in the United States surpassed two hundred thousand. Despite an over-all decline in infection and mortality rates since the spring, more than seven hundred people, on average, are dying every day from covid-19. “We have become used to this level of disease that is really pretty awful,” Eric Toner, a senior scholar with the Johns Hopkins Center for Health Security, recently told Politico. Still, Donald Trump and other political leaders have continued to flout restrictions, at a time when the stakes couldn’t be higher. In August, half a million motorcyclists attended the annual Sturgis rally, in South Dakota, encouraged by the state’s Republican governor, Kristi Noem, leading to at least one death and a hundred thousand infections across the country, according to one study. Despite the spike in coronavirus cases in Tulsa, Oklahoma, following Trump’s indoor campaign rally there, in June, he held another indoor campaign rally, in Nevada, on September 13th. Hundreds of unmasked supporters crowded into a manufacturing warehouse, violating the state’s ban on gatherings of fifty or more. More recently, at a campaign rally in Ohio, Trump said that the virus “affects virtually nobody.”

After two months of decline, the number of new cases nationwide has been rising steadily, now averaging around forty thousand per day. Anthony Fauci, the director of the National Institute of Allergy and Infectious Diseases, recently estimated that, in order to maintain control of the pandemic this winter, the country should be averaging less than ten thousand infections per day. “I would like to see that number in the very low thousands,” he told me. “Less than ten thousand. To be stuck at forty thousand cases a day, as a nation, is a precarious position.” Of course, we might have been better prepared. Back in May, Rick Bright, the former head of the U.S. Biomedical Advanced Research and Development Authority, who had been demoted a month earlier for insisting that the drug hydroxychloroquine should be rigorously tested, warned that, without any kind of national strategic plan, the country faced the “darkest winter in modern history.” We’re now staring down that barrel.

At the current rate of infection, daily deaths could climb back to two thousand per day by mid-November, according to the University of Washington’s Institute for Health Metrics and Evaluation. The group’s model, which uses a wide-ranging set of very specific assumptions—about climate, for instance, and about mobility—to hypothesize future scenarios, estimates that we could see a total of four hundred thousand deaths by the end of the year. Modellers are quick to caution, however, that estimating specific counts that far into the future is not much different from predicting the exact weather on any given day in December. Youyang Gu, a young data scientist who independently created one of the most accurate forecasting models available, acknowledged that a fall wave could increase daily deaths by mid-November. But he has not released projections that extend more than six weeks into the future. “There is no point,” he said. “It gives people a sense of certainty when there is no certainty.”

Although a clear set of guidelines exists for controlling the pandemic in the months ahead, there are still many variables, including a degree of chance. Because there are no borders within the U.S., and people can go where they want, many places “are going to feel like they’ve been so vigilant, and they are just going to get unlucky,” Nick Reich, the head of a lab at the University of Massachusetts, Amherst, and the creator of the covid-19 Forecast Hub, said. Although many experts also said that there is room for hope—chiefly, that communities and workplaces will take sufficient precautions to prevent the sorts of overwhelming outbreaks that took place in the spring—none were optimistic. They all emphasized the chaos caused by a lack of federal leadership. “No one I know expects it to be better,” Bill Hanage, an associate professor of epidemiology at the Harvard T. H. Chan School of Public Health, told me. “The question is: How much worse?”

Weather is the first, most obvious factor. Experts generally agree that, in temperate regions, colder weather will lead to more coronavirus cases, as it does with other respiratory viruses. They just cannot say exactly why. “There are ongoing debates for a lot of diseases,” Justin Lessler, an epidemiologist at Johns Hopkins University, told me. “Is it changes in social interactions that drive seasonality? Or is it actual biological and physical mechanisms?” The coronavirus spreads easily across a poorly ventilated room, where studies show it can linger for hours. “It’s all more intense inside,” Emily Gurley, another epidemiologist at Hopkins, said. Humidity plays a part, too. Evidence from flu studies shows that smaller particles travel farther when humidity is lower. Arid winter air dries out people’s airways, making them more vulnerable to infection. People cough more in the winter months. They are prone to Vitamin D deficiencies, too. Tom Frieden, a former director of the Centers for Disease Control and Prevention, pointed out that outbreaks among meatpackers have been common not only in the United States but all over Europe. “Think of what a meatpacking factory is,” he said. “It’s winter.”

The usual seasonal viruses, especially influenza, will also have negative impacts. There is the possibility of a one-two punch, particularly among older people: becoming infected first with a cold or flu, which weakens the respiratory system, and then with sars-CoV-2. Many hospitals already have trouble during bad flu years, and health-care providers are worried about a “twindemic,” in which facilities are doubly stressed by post-flu pneumonia patients and covid-19 patients. That said, every measure to control the coronavirus could also, potentially, control the flu, the common cold, and other seasonal viruses. More people might be inclined to get the flu vaccine now than in previous years. This winter could therefore see a mild flu season, as was the case this past winter in the Southern Hemisphere. School closures, travel restrictions, social distancing, and mask-wearing dramatically reduced flu transmission, even though sars-CoV-2, which is more infectious, continued to spread.

Clusters are possible anywhere—factories, offices, crowded housing developments—but an unpublished study of location data, by Google and a group of Harvard-affiliated hospitals, found that the policy associated with the greatest increase in social distancing was bar and restaurant closures. In June, a JPMorgan Chase analysis of credit-card spending found that in-restaurant purchases are the strongest predictor of increases in covid-19 cases. Currently, the fastest-rising case counts are in swaths of rural and suburban America—in states such as Wisconsin, the Dakotas, and Utah—which avoided outbreaks in the spring and summer. Cases have also risen rapidly in college towns. The New York Times found that more than forty-two thousand confirmed cases have been reported at American colleges since early September. In Florida, Governor Ron DeSantis, a Republican, just opened bars and restaurants at full capacity.

Gu told me that he’s unsure whether universities would have a big impact on the fatality rate. “If students that test positive are on campus, and don’t leave campus,” he said, “you’re effectively quarantining them.” The situation is different for younger students. Although children under ten spread the virus less than teen-agers and adults, they still present a risk. A new study from the C.D.C. and researchers in Salt Lake City found that children who had contracted covid-19 in child-care facilities transmitted the virus to at least twenty-six per cent of their outside contacts. The C.D.C. recommends that schools reopen only if the amount of virus spreading through a community is low—specifically, if the test-positivity rate is less than five per cent, or the average number of new cases is less than twenty per hundred thousand people. But some school districts have disregarded these recommendations. In Florida, where DeSantis aggressively pushed for schools to reopen for in-person instruction in August, nearly twelve thousand kids tested positive for the coronavirus during a four-week stretch, representing a twenty-six per cent increase in cases.

At the same time, guidelines for when a district should return to remote learning vary across municipalities and school districts. “Districts need clear thresholds for shutdowns,” Hanage said. If schools reopen, or refuse to close, in the face of higher community-transmission levels, students, teachers, and staff will bring the virus home from the classroom. And employees of one district might live, with their own children, in another. This patchwork of restrictions, half measures, budget shortages, and outright negligence—and the fact that every school district, college, municipality, and state is taking a different approach—could potentially lead to chaos, Hanage said. “And the virus will thrive on chaos.”

The news is not all bad for the United States. Since March, health-care providers’ understanding of how to treat covid-19 patients has improved, contributing to a decrease in mortality rates. The drug remdesivir has been shown to reduce recovery times and might even reduce fatality rates among the severely ill. In September, an international group of scientists published a body of pooled evidence, which proved that cheap and widely available steroids—dexamethasone, hydrocortisone, and methylprednisolone—can reduce deaths when administered to covid-19 patients late in the course of infection. (Because the steroids work by hampering the body’s immune system, they can be harmful if administered to patients with mild symptoms.) Other treatments may be available, including Eli Lilly’s experimental monoclonal antibody drug—a manufactured copy of an antibody from a person who has recovered from covid-19—which appears to notably reduce coronavirus levels in sick patients.

What will also help this winter are increased levels of immunity. “Even people who have mild infections get a pretty amazing antibody response,” Florian Krammer, a virologist at Mount Sinai, said. In one published study, Krammer and his collaborators called back a hundred and twenty patients who had tested positive for neutralizing antibodies and found that, after three months, their antibodies were stable. “Initially, you get a lot of them,” he said. “Between three and six months after symptoms, they start to go down”—but, in most of the patients he has studied, they do not disappear.

A recent study about a fishing boat offered striking evidence that neutralizing antibodies protect against infection. No one on the crew tested positive for the coronavirus before the boat departed, but three people did test positive for neutralizing antibodies. Nevertheless, once out at sea, there was an outbreak on board. Most passengers were infected, but the three men with neutralizing antibodies were not. “It’s extremely unlikely that those three people just by chance did not get it,” Krammer, who was not involved in the study, said. Questions still remain about the durability of antibodies, and who is likely to have them, but antibodies clearly provide some level of protection. Even with 33.4 million cases around the world, reinfections have been exceedingly rare. If a second infection does occur, it is likely to be much weaker, if not asymptomatic, as was the case recently with a thirty-three-year-old man in Hong Kong.

Originally published at new yorker

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