Editor’s Note: View cold and flu activity in your location with the WebMD tracker.
Nov. 21, 2022 — The 2022-2023 flu season continues its early start as respiratory disease activity according to a new report from the CDC.
A key measure of the severity of the season, the proportion of influenza-like illness (ILI) outpatient visits rose to 5.8% in the week of November 6-12. The last flu season to see such high activity so early was 2009-10, when visits for flu-like illness hit 7.7% in mid-October, CDC data shows. In the same season, attendance fell quickly and was back to normal by early January.
However, as with so many other things, the advent of COVID-19 has led to changes in how flu activity is measured.
About a year ago, the CDC changed the definition of a flu-like illness to exclude specific mention of the flu itself, which brought COVID-19 and respiratory syncytial virus (RSV) into play, as both patients often have a fever plus a cough or sore throat. All three viruses are monitored by the CDC’s Outpatient Influenza-like Illness Surveillance Network, which monitors outpatient visits for respiratory illness.
As the CDC monitors flu-like illnesses, a potential wild card emerges from research showing these viruses don’t play well together.
Researchers in Canada reported in February that the flu virus interferes with the coronavirus that causes COVID-19 and helps keep the coronavirus from replicating itself. The reverse is also true, where the coronavirus can disrupt the flu virus, the researchers reported in a study published in the journal viruses.
Likewise, there is evidence that rhinoviruses, which cause the common cold, can disrupt the coronavirus.
Some experts believe this means all three viruses are unlikely to peak at the same time and overwhelm the healthcare system.
Despite the CDC’s change in tracking definitions, activity during the 2021-22 flu season was below average: the national flu-like illness rate never reached 5% and fell below the current national baseline (an average of the past three non-COVID flu seasons plus 2021- 22 and selected weeks 2019-20) through the end of January.
That doesn’t appear to be the case in 2022-23.
“So far this season, there have been at least 4.4 million illnesses, 38,000 hospitalizations, and 2,100 deaths from influenza,” the CDC said in its influenza division’s weekly report, noting that the hospitalization rate “is higher than the observed rate [at the same point] in every previous season since 2010-2011.”
Of those 2,100 influenza-related deaths this season, seven are children. That’s more than in 6 weeks of the 2021-22 season, when the first fatality out of a total of 44 did not occur until week 8, and in the entire 2020-21 season, when there was only one. In the three preceding flu seasons, 199 (2019-20), 144 (2018-19), and 188 (2017-18) children died from the flu. said the CDC.