Will warm weather stop the coronavirus, or is it here to stay?

Summer is coming, and for millions of Americans isolating at home due to the coronavirus pandemic, getting out in the sun would be a breath of fresh air. It’s no surprise that people are grasping at reports that summertime will see a drop in infections, but is there any evidence that’s the case, or is it more misinformation? Here’s what we know so far.

Why do people think summer might slow the virus?

The idea that summer weather could stop the pandemic isn’t uncommon; even the Department of Homeland Security has expressed optimism, citing a study suggesting that high humidity or temperatures could kill the virus, and President  Donald Trump has also touted the potential of UV light in eliminating the virus.

It’s not an unreasonable idea. Some epidemics throughout history, like the flu, have followed seasonal patterns, with infection rates surging and receding like the tides. This applies to past coronaviruses (such as those that can cause the common cold), which tend to flourish in winter.

However, it’s important to note that not all viruses follow strict season patterns, and even for those that do, the precise causes are debated among epidemiologists. Some research suggests that it might actually be the human body that undergoes seasonal changes, the immune system weakening in cold weather.

Is there evidence regarding COVID-19?

An empty public park
An empty public park Andy Boxall/DigitalTrends.com

Some preliminary (not yet peer-reviewed) studies on COVID-19 have found a correlation between higher temperatures and humidity and lower incidences of infection. Early studies should be taken with a grain of salt, however. As the National Academies of Science, Engineering, and Medicine explains, laboratory studies aren’t able to perfectly capture real-world conditions, and studies on COVID-19, in particular, have been conducted on very short time frames. The disease is still relatively new, and there are still plenty of things researchers don’t know about it.

The National Academies report also points out “the failure or inability of some laboratories to control and vary relative humidity for their experiments,” adding that “Differences in experimental conditions across studies … would be expected to contribute to variation in study results.”

The “real-world” course of the pandemic shows just how differently things can go, with some hot and humid countries (Iran and Ecuador, for example) suffering huge numbers of coronavirus cases.

A summer drop might not mean the end

man checking phone with mask on
Milorad Kravic / Getty Images

Even if countries like the U.S. do see a drop in coronavirus cases during the summer, it wouldn’t mean the pandemic is over. Some experts are worried the pendulum will swing back in the fall or winter.

A striking example is the 1918 flu pandemic, which first erupted in spring, then surged in fall, and had another wave in winter, finally wrapping up in the summer of 1919.

Centers for Disease Control Director Robert Redfield is among those warning that the U.S. could be in for a severe second wave in the fall when flu season will also be in effect, according to an interview with the Washington Post, a combination that could be dire for the healthcare system.

For the latest updates on the novel coronavirus outbreak, visit the World Health Organization’s COVID-19 page.

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