Rapid weather swings increase flu risk

New research from a team of Florida State University scientists shows that rapid weather variability as a result of climate change could increase the risk of a flu epidemic.

An international team looked at historical data to see how significant weather swings in the fall affect flu season in the northern-mid latitudes of the world, including the United States, mainland China, Italy, and France. Researchers analyzed weather patterns and average temperatures from Jan. 1, 1997, to Feb. 28, 2018, and also tracked influenza data over the same time period.

Previous research suggested low temperatures and humidity in the winter create a favorable environment for transmitting the flu virus. However, the 2017-2018 flu season was one of warmest on record and yet also one of the deadliest. The Centers for Disease Control reported 186 children's deaths during the 2017-2018 season. The previous high was 171 during the 2012-2013 season.

During the 2017-2018 flu season, scientists found that the extreme fluctuations in weather during the fall essentially kick-started the flu early in the season then snowballed, given the contagious nature of the virus.

"The historical flu data from different parts of the world showed that the spread of flu epidemic has been more closely tied to rapid weather variability, implying that the lapsed human immune system in winter caused by rapidly changing weather makes a person more susceptible to flu virus," said Zhaohua Wu, associate professor of meteorology at Florida State University.

The issue going forward, scientists noted, is that rapid weather variability is common in warming climates. Having a better understanding of those weather patterns may be key to determining the severity of any future flu season threat. If these climate models are correct, there is an anticipation of increased flu risk in highly populated areas. Under this scenario, Europe could see a 50 percent increase in deaths tied to flu.

"The autumn rapid weather variability and its characteristic change in a warming climate may serve not only as a skillful predictor for spread of flu in the following season but also a good estimator of future flu risk," said Wu.

Source: Florida State University: news.fsu.edu