Tracking coronavirus around the world from 725 West Baltimore Street | COMMENTARY

Black circles on this climate map represent outbreak areas in countries with significant community transmission of the coronavirus between December and early March. (Institute of Human Virology; Climate Change Institute, University of Maine)

An old complaint about the weather in central Maryland and the southern edge of the mid-Atlantic is that we don’t get much of a spring here. In many years, the climate seems to jump from winter to July, and going from zero to 90 in three weeks makes a lot of people cranky.

But, given pandemic and national emergency, we might want to refrain from complaining about the lack of a long, cool spring and root for sudden summer.


And while President Donald Trump continues to make misleading statements about the coronavirus and the botched federal response to its emergence, he might be correct about one thing: Warming temperatures could make it “go away,” at least for a time. A just-published analysis from virologists in Baltimore suggests a possible seasonality to the coronavirus.

Researchers at 725 West Baltimore Street, home of the Institute of Human Virology, part of the University of Maryland School of Medicine, wanted to know if climate could be a factor in the community spread of coronavirus. So they tracked it around the globe. During the first three months of the outbreak, they found COVID-19 spreading under specific conditions and along a consistent path, a kind of coronavirus zone.


Outbreaks have been reported in urban areas with average winter temperatures of 41 to 52 degrees Fahrenheit and average humidity of 47 to 79 percent. “There is a similarity in the measures of average temperature [and humidity] in the affected cities and known laboratory conditions that are conducive to coronavirus survival,” the study found.

In addition, the Maryland researchers noticed that the epicenters of the disease were roughly along the same latitude, in an east-west pattern — China (specifically Wuhan, the source of the outbreak), South Korea, Japan, Washington state (specifically Seattle), northern California and Iran.

Many respiratory viruses are considered seasonal and appear to thrive in temperate climates. The team at the IHV started to see another characteristic of the coronavirus transmission — it did not appear to occur to a significant degree in tropical countries south of China nor in cold countries such as Russia.

“The seven major outbreaks we studied as of early March occurred in regions with a very similar latitude and strikingly similar temperature and humidity pattern,” says the leader of the study, Dr. Mohammad Sajadi, an associate professor at the IHV and a member of the Global Virus Network. “To us, this was suggestive that temperature and humidity could hold a key role in transmission, and as with similar respiratory viruses, this one was potentially seasonal.

“In temperate areas, respiratory viruses typically come on in the fall and/or winter, and diminish significantly by spring and/or summer. We predicted certain areas to be at the highest risk right now and in the near future.”

Using weather data from 2019, and looking at areas with similar temperature and latitude, Sajadi’s team predicted that COVID-19 could affect areas just north of the current areas at risk.

“These could include (from east to west) Manchuria, Central Asia, the Caucuses, Eastern Europe, Central Europe, the British Isles, the Northeastern and Midwestern United States, and British Columbia,” the study said. “However, this simplified analysis does not take into account the effect of warming temperatures. The marked drop in cases in Wuhan could well be linked to corresponding recent rising temperatures there.”

This is why I say people in Maryland and the Mid-Atlantic generally, if not the Northeast, including New England, might root for a fast run to summer. A long, slow spring would bring the temperate climate that appears to be conducive to the spread of the disease.


A purpose of the IHV study was to build a weather model that might help predict the path and duration of the virus. “For many,” the study notes, “the biggest concern [with coronavirus] is not how large the problem but what will happen in the coming months and which areas and populations are most at risk.”

Having some understanding of that, Sajadi’s team said, “allows for concentration of public health efforts on surveillance and containment.”

The study notes that, “although the current correlations with latitude and temperature seem strong, a direct causation has not been proven and predictions in the near term are speculative and have to be considered with extreme caution.”

And I hasten to add that hoping for virus-dissipating weather — wishing coronavirus will just “go away” when the peonies bloom — is no substitute for the important local actions being taken to slow transmission in Maryland and other states. Given the nation’s poor start in dealing with the novel virus and the woeful lack of testing for the disease, the measures we’ve been asked to embrace make the most sense.

“I know everyone in Maryland would like to know when there might be a decrease in cases,” says Sajadi. “What we proposed was a prediction based on the evidence we had at hand, and only time will tell if we were correct. For now, the best thing to do is to take the advice of public health officials in limiting the spread of this virus.”

Wash your hands frequently or, as I recently heard it stated: “Wash your hands as if they’re covered in Old Bay and you need to put your contacts in.”


Work from home if you can. Avoid crowds. Look out for your neighbors, but keep your distance. Root for summer.