“Sunlight kills most pathogenic microbes quite rapidly,” John Postgate, a British microbiologist, wrote two decades ago in the popular book “Microbes and Man,” published by Cambridge University Press. The lethality, he continued, is principally the result of “the ultraviolet component of solar radiation. Ultraviolet lamps can be used indoors to sterilize the air in operating theaters and pharmaceutical and microbiological laboratories. Even in diffuse daylight there is an appreciable amount of light of the effective wavelength.”

During the pandemic, because of the shortage of protective equipment, some medical centers have been using ultraviolet light to decontaminate masks so they could be reused. A small industry that sells ultraviolet lamps as a germicide has arisen, but experts warn of their potential dangers for humans.

Many nonscientists — including President Trump — have noted the seasonality of colds and flu and hoped the novel coronavirus would act likewise. Dr. Robert R. Redfield, director of the Centers for Disease Control and Prevention, told National Public Radio last month that he, too, expected an ebb and flow of disease.

“Most respiratory viruses have a seasonality to them,” he said. “It’s reasonable to hypothesize — we’ll have to wait and see — but I think many of us believe as we’re moving into the late spring, early summer season, you’re going to see the transmission decrease.” But in comments this week to The Washington Post, he also pointed to the likelihood that the coronavirus would continue to be a problem in the fall, when it would coincide with the start of a new flu season.

Comparative studies of viruses suggest that, as a class, coronaviruses are especially vulnerable to ultraviolet light because of their relatively large genetic codes. “The more target molecules,” one study noted, “the more likely the genome will be damaged.”

Even so, other aspects of sunlight’s effects may also play important roles in whether viruses can easily infect humans — a main one being its promotion of the synthesis of vitamin D, a nutrient that can strengthen the immune system and lower the risk of certain illnesses.

The Connecticut scientists — Cory Merow and Mark C. Urban — titled their paper “Seasonality and Uncertainty in Covid-19 Growth Rates.” It was posted Wednesday on medRxiv, a preprint website for health scientists run by Yale University, the Cold Spring Harbor Laboratory on Long Island, and the company that publishes the British Medical Journal. The site notes that its preprints have not undergone peer review for accuracy and thus “should not be used to guide clinical practice.”