Unlike the flu, coronavirus doesn’t have a season
Viruses sail freely from person to person in the cool, dry air of winter, slowing as the weather warms and humidity weighs down the infectious spew.
But the novelty of the coronavirus – its introduction to a previously untouched population – means it could bulldoze through the spring virus barrier that limits most flu seasons.
While scientists struggle to understand the recently rebranded Covid-19 virus, the Centers for Disease Control and Prevention said its transmission is similar to how the flu works. It mainly spreads from person to person who are within about 6 feet of each other, or through respiratory droplets sneezed or coughed out by an infected person.
When temperatures are colder, with low humidity, airborne virus particles set adrift by can stay mobile much longer. Warm temperatures can cause a virus-carrying mucus droplet to evaporate before making it to its next victim. Water vapor in humid environments can also attach to a droplet and drag it to the ground faster.
It’s also true in winter, people spend more time indoors in closer contact with those who are potentially infected.
“The short answer is the (new coronavirus) can be less contagious when the weather is warmer, but it is probably too much to hope that the warm weather will stop this virus completely,” said Michael Farzan, chairman and a professor in the Department of Immunology and Microbiology at the Scripps Research Institute in Jupiter. “Indeed, the impact of summer may be more modest than with the flu.”
The unknowns with the coronavirus haven’t stopped world leaders from speculating on whether weather will play a role in reducing cases.
President Donald Trump said on Feb. 10 that the virus may go away in April “with the heat.”
Brazil Health Minister Luiz Henrique Mandetta also said the country’s tropical climate and warm weather could slow the spread of the disease. Brazil’s first case of coronavirus was diagnosed last week.
Glenn Morris, director of the University of Florida’s Emerging Pathogens Institute, said it’s too early to know how weather will impact the coronavirus.
The natural biology of viruses is that they can remain viable in the environment for many days when the temperature is below about 74 degrees and relative humidity is 40 percent or lower, said Dr. John Lednicky, a research professor at UF’s College of Public Health and Professions.
That means the number of new cases of coronavirus acquired in the environment, as opposed to close contact with an infected person, should go down as temperatures warm.
“While we expect modest declines in the contagiousness of (the coronavirus) in warmer, wetter weather, and perhaps with the closing of schools in temperate regions of the Northern Hemisphere, it is not reasonable to expect these declines alone to slow transmission enough to make a big dent,” said Marc Lipsitch, director of the Center for Communicable Disease Dynamics at the Harvard T.H. Chan School of Public Health.
Lipsitch wrote a 4-page fact sheet on the coronavirus, noting that the newness of the virus gives it a temporary, but important advantage - few people are immune to it.
Also, because few cases have been diagnosed in children, it’s unclear if closing schools or having schools closed during the summer will reduce the coronavirus spread, Lipsitch said.
Some doctors said travel, not weather, will have the biggest impact on continued transmission of the virus. But that’s no reason to cancel vacations to areas not on the CDC’s high risk list.
Dr. Kyle Petersen, medical director for American Family Care in Loxahatchee, is going on a cruise this month and has no plans to reschedule.
“It’s not affecting my travel plans at all. I’m not going to China,” Petersen said. “I think it’s being a little blown out of proportion.”
On a concern scale of 1 to 10, coronavirus ranks a 2 for Petersen - no more dangerous than the flu.
“Our goal needs to be that we slow this virus so that our healthcare infrastructure does not get overwhelmed,” Farzan said. “Anything any one of us now does to slow transmission – wash hands, stay distant from others, minimize unnecessary interaction in groups, wash surfaces, limit air travel – can help.”