Influenza-like activity soars again during historic flu season amid escalating pandemic

Visits to health care providers for flu-like illnesses increased for the third straight week, jumping 13.2 percent from last week. The Centers for Disease Control and Prevention (CDC) notes the coronavirus (COVID-19) outbreak in the United States "may affect healthcare-seeking behavior, which, in turn, would impact data" it receives from its influenza-like illness (ILI) network.

A total of 6.4 percent of such visits to health care providers were for ILI activity; that number was 5.6 percent last week. The highest peak during all of last year's difficult flu season was 5.1 percent.

The increase was not a surprise for experts in the field of infectious diseases.

"This is a significant event that may continue to cause continued challenges for influenza forecasting into the fall," Dr. Bryan Lewis, a professor at the Biocomplexity Institute, told AccuWeather. "We are already altering these methods to try and forecast COVID-19 and because it will be tracked by the ILI surveillance system, the forecasts in the coming weeks will be capturing this activity."

Source: CDC

This season figures to be the longest above-baseline flu season in at least 20 years of CDC records. This is the 19th straight week flu activity is above baseline normal (2.4 percent).

Flu-like activity has had a longer stretch only once since 1999-2000, according to CDC records, and this season's third spike is expected to continue upward, according to researchers. Last year's above-baseline activity went for 20 weeks; in 2014-15, a stretch lasted 19 weeks also.

CLICK HERE FOR THE FREE ACCUWEATHER APP

U.S. confirmed cases of COVID-19 have increased almost 80 percent in 10 days, going from 52,000-plus on March 17 to roughly 93,000 as of Friday March 27. The virus has now spread to 176 countries or regions with more than 566,000 confirmed cases and at least 25,000-plus deaths. More than 127,000 people have recovered from coronavirus cases, according to data from the Johns Hopkins Coronavirus Resource Center.

Laboratory-confirmed, influenza-associated hospitalization rates for the U.S. population overall are higher than most recent seasons and rates for children 0-4 years old and adults 18-49 are the highest the CDC has on record, surpassing rates reported during the 2009 pandemic, according to the CDC.

Raeanne Castillo, at right, with Roper St. Francis Healthcare gives specimen collection kits to a LabCorp employee at the hospital's North Charleston office on March 16, 2020, in North Charleston, S.C. Roper St. Francis Healthcare was providing drive-thru specimen collecting for patients suspected of having COVID-19 or flu who have already been screened by a Virtual Care provider. (AP Photo/Mic Smith)

The CDC estimates there have been at least 39 million flu illnesses, 400,000 hospitalizations and 24,000 deaths from the flu during the 2019-20 season.

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.

Keep checking back on AccuWeather.com and stay tuned to the AccuWeather Network on DirecTV, Frontier and Verizon Fios.