Like Flu, COVID-19 May Turn Out to Be Seasonal

Like influenza, could COVID-19 evolve to wax and wane with the seasons? New research suggests it might.

Early in the pandemic, some experts suggested that SARS-CoV-2 — the virus that causes COVID-19 — may behave like many other coronaviruses that circulate more widely in fall and winter.

To find out if that could be true, researchers analyzed COVID-19 data — including cases, death rates, recoveries, testing rates and hospitalizations — from 221 countries. The investigators found a strong association with temperature and latitude.

“One conclusion is that the disease may be seasonal, like the flu. This is very relevant to what we should expect from now on after the vaccine controls these first waves of COVID-19,” said senior study author Gustavo Caetano-Anollés. He is a professor at the C.R. Woese Institute for Genomic Biology at the University of Illinois at Urbana-Champaign.

The same research team previously identified areas in the SARS-CoV-2 virus genome undergoing rapid mutation.

Similar viruses have seasonal increases in mutation rates, so the researchers looked for connections between mutations in SARS-CoV-2 and temperature, latitude and longitude.

“Our results suggest the virus is changing at its own pace, and mutations are affected by factors other than temperature or latitude. We don’t know exactly what those factors are, but we can now say seasonal effects are independent of the genetic makeup of the virus,” Caetano-Anollés said in a university news release.

Further research is needed to learn more about how climate and different seasons may affect COVID-19 rates, the team added.

The study authors suggested that people’s immune systems may play a role. The immune system can be influenced by temperature and nutrition, including vitamin D, which plays an important role in immunity. With less sun exposure during the winter, most people don’t make enough vitamin D.

“We know the flu is seasonal, and that we get a break during the summer. That gives us a chance to build the flu vaccine for the following fall,” Caetano-Anollés said. “When we are still in the midst of a raging pandemic, that break is nonexistent. Perhaps learning how to boost our immune system could help combat the disease as we struggle to catch up with the ever-changing coronavirus.”

The study was published online Jan. 26 in the journal Evolutionary Bioinformatics.

More information

The U.S. Centers for Disease Control and Prevention has more on COVID-19.

SOURCE: University of Illinois at Urbana-Champaign, news release, Jan. 27, 2021

Source: HealthDay