Evidence is piling up that COVID transmission is seasonally driven. But that doesn't mean we can predict it perfectly yet, Rachel Gutman reports.
"Now we have nearly two years’ worth of data—from eight full seasons of pandemic—to pick apart for clues. We also know something we didn’t in spring 2020: In all likelihood, we will not eradicate COVID. That makes it all the more important that we know how cases might ebb and flow with weather in the months and years to come.
"Anyone who lives in a temperate climate has an intuitive understanding of seasonal disease. The most canonical example is the common cold—just look at what it’s named. But infecting more people in cold weather is far from the only once-a-year cycle a disease can settle into. Lyme disease peaks in the summer. Polio was historically a summer sickness. Even genital herpes tends to spike around the spring and summer in the United States. The same disease can also show different patterns in different places. Americans are used to a winter flu season, but in Bangladesh, flu cases spike during the monsoon season, which runs from May to September and is the warmest part of the year," Gutman continues. "To acknowledge a strong seasonal influence might feel like admitting defeat: If Louisiana is going to face devastating case rates every summer, and Minnesota will fall prey to a winter surge like clockwork, how much can we really do? But a regular pattern doesn’t have to mean inevitable suffering. Pandemic-fighting policies can take strategic account of seasonality; they’ve done so before."COVID Sure Looks Seasonal Now
After two years of pandemic waves, we’re finally learning whether the disease has a predictable schedule.By Rachel GutmanThe first part of what may be the first epidemiologic text ever written begins like so: “Whoever wishes to investigate medicine properly, should proceed thus: in the first place to consider the seasons of the year.”
The book is On Airs, Waters, and Places, written by Hippocrates around 400 B.C. Two and a half millennia later, the Northern Hemisphere is staring down its coming season of the year with growing apprehension. America’s grimmest phase of the coronavirus pandemic so far occurred from November 2020 to February 2021. Now the calendar has turned to a new November, and even though the majority of Americans are fully vaccinated against COVID-19, cases are once again, horrifyingly, on the rise.
If Hippocrates was right, we could be doomed to repeat the sickness and death that defined last winter. To be fair, Hippocrates also thought that among the most important factors in anyone’s health was their balance of black and yellow bile. But evidence is piling up that COVID really is a seasonal disease, surging with the weather and the annual rhythms of human life. If that’s the case, then understanding those seasonal patterns could help us predict where the virus is headed next, and address its attacks in advance.
The seasonal-COVID hypothesis, and its promised benefits for pandemic planning, have been around nearly as long as the disease itself. Way back in February 2020, President Donald Trump predicted that in April, “when it gets a little warmer,” the coronavirus would “miraculously” disappear. That clearly didn’t happen, but evidence of seasonality, the thinking went, might show up in summer, when things got
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