New York: This winter’s mild flu season has faded to a trickle of cases in much of the U.S., but health officials aren’t ready to call it over.
Since the beginning of the year, positive flu test results and doctor’s office visits for flu-like illness are down. But second waves of influenza are not unusual, and some experts said it’s possible a late winter or spring surge could be coming.
COVID-19 cases have been falling, leading to a decline in mask wearing and behaviors that may have been keeping flu down this winter. As people are less cautious, flu or other respiratory viruses can surge, Brammer said.
Some indicators of flu activity have inched up the last couple of weeks: a count of flu-related hospitalizations and the percent of specimens from patients with respiratory illnesses that test positive for flu.
Limited data on who is testing positive for flu suggest about two-thirds are kids and young adults. Kids have driven flu’s spread in past years, so “it’s quite possible we could see continued increases,” Brammer said.
Dr. Angela Branche, a University of Rochester infectious diseases specialist, called the flu season unusual.
“I don’t have any (flu) cases in my practice this week,” she said recently. Normally, doctors in Rochester would be diagnosing 50 to 100 flu cases a day around this time of year.
It seems like the current flu season is “easing to the finish line,” said Dr. William Schaffner, a Vanderbilt University infectious diseases expert. But viruses can be unpredictable.
Some doctors were nervous about how things would go this winter, wondering if last year’s lull would cause flu immunity to wane. Also, fewer children and adults got flu shots this year, according to preliminary CDC data.
The worry seemed to be legitimized by an early November flu outbreak at the University of Michigan in Ann Arbor, where more than 700 cases were reported. The illnesses were caused by a certain version of flu — called Type A H3N2 — that traditionally leads to more hospitalizations and deaths, particularly among the elderly. Worse, many of the infected kids were vaccinated, and investigators concluded the shots offered low levels of protection.
That strain later became the main cause of flu illnesses across the country. But this season has nevertheless turned out to be tame.
That was a surprise, said Dr. Edward Belongia, a flu expert at the Wisconsin-based Marshfield Clinic Research Institute.
The CDC has not yet released estimates of the current vaccine’s effectiveness but it is expected to do so next week.
