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.

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.

Some preliminary (not yet peer-reviewed) studies on COVID-19 have found a correlation between higher temperatures and humidity and lower incidences of infection.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 drop in the number of COVID cases during the summer months does not necessarily mean the end of the pandemic is near. In fact, with winter and flu season right around the corner, case numbers again appear to be steadily rising. 

There are such few apt comparisons for the coronavirus that the century-old 1918 flu pandemic seems to be the best we can draw from. The flu first made its appearance in the spring. Although case numbers dropped in the fall, there was another spike that next winter. The pandemic didn’t end until the 1919 summer season. 

Centers for Disease Control Director Robert Redfield is among those warning that the U.S. could be in for a severe second wave when flu season will also be in effect, according to an interview with the Washington Post, a combination that could spell disaster for overstressed hospitals and healthcare systems across the country. 

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

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