Reports of flu incidents declined, according to the latest data released Friday by the Centers for Disease Control and Prevention (CDC). But there may be bad news ahead with a possible flu rebound in the future, experts warn.
Visits to health care providers for influenza-like illnesses (ILI) decreased from 7 percent last week to 5.8 percent this week, ending three straight weeks of increasing visits. While flu activity remains high - and above the national baseline of 2.4 percent - CDC indicators that track severity (hospitalizations and death) are not high at this point in the season, the CDC notes.
The lack of high severity is likely due to the predominance of Influenza B/Victoria and Influenza A(H1N1), which are more likely to affect children and younger adults than the elderly and subsequently result in fewer hospitalizations and deaths, according to the CDC.
The CDC estimates that so far this season there have been at least 9.7 million flu illnesses, 87,000 hospitalizations and 4,800 deaths from the flu in the U.S. It's the eighth straight week flu activity is above baseline normal; last year, levels of ILI in the U.S. were at or above baseline for 21 straight weeks.
However, experts predict incidents of ILI may have another spike. If so, this flu season would have a similar track to the 2017-18 and 2014-15 flu seasons (see chart).
"We expect initial peaks to be reached in many states in the next couple of weeks; however, second peaks of activity remain expected," said Dr. Bryan Lewis, a professor at the Biocomplexity Institute at the University of Virginia who works with a team in a research partnership with AccuWeather.
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. For example, there is no real flu season in the tropics.
“AccuWeather believes the weather and the sunshine intensity are important factors in the flu season; there is no flu to speak of in the summer because the sun is strong and the weather is warm,” said company founder and CEO Dr. Joel N. Myers.