A third spike in influenza-like illness (ILI) activity in the United States now puts the 2019-20 flu season on track to be perhaps the longest in at least the last 20 years of record-keeping by the Centers for Disease Control and Prevention (CDC).
The influence of the new coronavirus (COVID-19), which is leading to more people reporting flu-like symptoms, is adding to the difficult season.
“The upticks in activity in some regions may be related to COVID-19 infections as they would be captured by the same surveillance systems as influenza,” Dr. Bryan Lewis, a professor at the Biocomplexity Institute, told AccuWeather. “As we are starting to see, this pandemic has the capability of causing significant morbidity and mortality.”
By Monday afternoon, COVID-19 had spread to more than 155 countries or regions with more than 179,000 confirmed cases and 7,000 deaths. In the U.S., more than 4,000 confirmed cases and at least 69 deaths had been recorded by health officials.
Visits to health care providers for ILI increased for the first time after three straight weeks of declining activity, going from 5.1 percent last week to 5.2 percent this week, according to the CDC. The highest peak during all of last year’s difficult flu season was 5.1 percent.
“This season remains extremely active and should continue to be so for a couple more weeks,” said Lewis, one of the researchers at the Biocomplexity Institute at the University of Virginia who work in a research partnership with AccuWeather.
Half of the states in the U.S. (25) are showing a higher level of ILI activity than ever for this time of year, according to the Biocomplexity Institute researchers. And a total of 41 states are at high ILI activity levels, according to the CDC.
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It’s the 17th straight week flu activity is above baseline normal (2.4 percent). Last year, levels of ILI in the U.S. were at or above baseline for 20 straight weeks, which is the longest stretch since at least 1999-2000, according to CDC records.
An estimated 36 million people have experienced flu illnesses in the U.S. this season, with 370,000 hospitalizations and 22,000 deaths from the flu, according to the CDC. Laboratory-confirmed flu-related hospitalization rates overall for the U.S. remain moderate compared to recent seasons, but rates for children 0-4 and adults 18-49 are now the highest the CDC has on record for these age groups, surpassing rates reported during the 2009 H1N1 pandemic.
A woman looks at the few selections remaining in the cold and flu aisle of a Walmart near Warrendale, Pa., Friday, March 13, 2020. (AP Photo/Gene J. Puskar)
Flu activity is expected to maintain high levels in the North, stretching from the Pacific Northwest across to New England and dipping into the central Plains, noted the Biocomplexity Institute researchers. Activities in the South and mid-Atlantic should continue to decline and return to pre-season levels in the coming weeks.
Flu season typically begins in October, peaks between December and February and lasts well into March, although activity can last as late as May. Flu viruses are more stable in cold air and the low humidity allows the virus particles to remain in the air, according to Peter Palese, who was the lead author on a key flu study in 2007.
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