News from the FDA/CDC

Flu activity down from its third peak of the season, COVID-19 still a factor


Influenza activity measures dropped during the week ending March 28, but the percentage of deaths attributed to pneumonia and influenza (P&I) has risen into epidemic territory, according to the Centers for Disease Control and Prevention.

This influenza news, however, needs to be viewed through a COVID-19 lens.

The P&I mortality data are reported together and are always a week behind the other measures, in this case covering the week ending March 21, but they show influenza deaths dropping to 0.8% as the overall P&I rate rose from 7.4% to 8.2%, a pneumonia-fueled increase that was “likely associated with COVID-19 rather than influenza,” the CDC’s influenza division noted.

The two main activity measures, at least, are on the same page for the first time since the end of February.

The rate of outpatient visits for influenza-like illness (ILI) had been dropping up to that point but then rose for an unprecedented third time this season, a change probably brought about by COVID-related health care–seeking behavior, the influenza division reported in its weekly FluView report.

This corresponding third drop in ILI activity brought the rate down to 5.4% this week from 6.2% the previous week, the CDC reported. The two previous high points occurred during the weeks ending Dec. 28 (7.0%) and Feb. 8 (6.7%)

The COVID-related changes, such as increased use of telemedicine and social distancing, “impact data from [the Outpatient Influenza-Like Illness Surveillance Network] in ways that are difficult to differentiate from changes in illness levels and should be interpreted with caution,” the CDC investigators noted.

The other activity measure, positive tests of respiratory specimens for influenza at clinical laboratories, continued the decline that started in mid-February by falling from 7.3% to 2.1%, its lowest rate since October, CDC data show.

Overall flu-related deaths may be down, but mortality in children continued at a near-record level. Seven such deaths were reported this past week, which brings the total for the 2019-2020 season to 162. “This number is higher than recorded at the same time in every season since reporting began in 2004-05, except for the 2009 pandemic,” the CDC noted.

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