Flu season is here – and early red flags suggest it’s on track to be very, very bad. The latest data from the Centers for Disease Control and Prevention (CDC) Flu view The report shows an extraordinarily high number of positive flu tests reported to the agency by labs in the United States. As of November 5, almost 14,000 positive flu tests have been reported, as shown by the orange line in the graph below. This is more than 12 times the number reported at the same time in 2019 (indicated by the black line).
The early and dramatic increase in influenza transmission this year is at least somewhat related to more people being tested for influenza than in previous years. Over the past five weeks, nearly twice as many flu tests have been performed in clinical labs nationwide than during the same period last year (about 460,000 compared to 254,000 ). More testing means more cases will be detected.
But there are other signs that these numbers represent real and very frightening trends.
For starters, a much higher proportion of flu tests are turning out positive compared to previous years: in recent bad flu seasons, test positivity has reached approximately 3.6%but last week almost 13 percent flu tests were positive. When a higher proportion of tests are positive, it means that more people who feel sick actually have the flu than in previous years.
Worrying signals are also coming from medical practices and hospitals. At this time of year, only 1-2% of outpatient clinic patients typically report flu-like illnesses. But right now that number is up 5 and a half percent, according to the CDC. Not all of these patients actually have the flu – many could have RSV or other infections – but in combination with the flu testing numbers, it’s concerning.
Moreover, more than five times as many people have been hospitalized with the flu so far this season than at the same time in the past 10 years. And unlike RSV, which poses the greatest threat to young and old, severe illness from influenza is more evenly distributed across age groups. About a third of people hospitalized with the flu this year were 65 or older, while another quarter were between 18 and 49.
These are particularly worrying signs given the health care the pressure on the workforce that we have already seen during the ongoing RSV outbreak. And this early start does not mean that this flu wave will be a flash in the pan. The flu is currently worse in the southeastern United States, but that will almost certainly change as the air cools and the virus migrates north. Plus, cases haven’t peaked this early since 2009-10. not good, very bad H1N1 flu pandemic.
The good news: there is a lot you can do to protect yourself from the flu. This year’s flu shot is widely available and free with most insurance plans. And because the two dominant influenza strains currently circulating have been included in this year’s vaccine formulationthere is hope that the vaccine will help prevent serious illness in people who have it.
There are also medicines to treat the flu, so if you are sick and at risk of flu complicationssee a doctor early.
And all that masking, ventilating, and filtering the air that we’ve learned to do during the pandemic does a lot to prevent flu transmission (not to mention all the other respiratory nasties out there).
The transmission of influenza in fact dropped dramatically during the pandemic. In the graph above, look at the blue lines, which represent cases reported over the past two years. You can see there were very few positive tests in 2020, when mitigation measures – like widespread masking – were still in place and most children weren’t in school buildings. Transmission resumed in 2021, but was on track with previous seasons – and was likely curbed from the end of the year due to increased masking and social distancing in response to the surge of omicron from Covid-19.
The start of flu season this year is scary. But we can still take steps to flatten that curve.