News from the FDA/CDC

2018-2019 flu season: Going but not gone yet


The 2018-2019 flu season again showed real signs of ending as influenza activity levels dropped during the week ending March 23, according to the Centers for Disease Control and Prevention.

Influenza-like illness activity level, week ending March 23, 2019

Despite those declines, however, current levels of influenza-like illness (ILI) activity are still elevated enough that the CDC issued a health advisory on March 28 to inform clinicians about the “increasing proportion of activity due to influenza A(H3N2) viruses, continued circulation of influenza A(H1N1) viruses, and low levels of influenza B viruses.”

The CDC’s weekly flu report, released March 29, does show that the overall burden is improving. The national proportion of outpatient visits for ILI dropped from 4.3% for the week ending March 16 to 3.8% for the latest reporting week, the CDC’s influenza division reported. The figure for March 16 was originally reported to be 4.4% but was revised in the new report.

The length of this years’ flu season, when measured as the number of weeks at or above the baseline level of 2.2%, is now 18 weeks. By this measure, the last five seasons have averaged 16 weeks, the CDC noted.

Influenza was considered widespread in 34 states and Puerto Rico for the week ending March 23, down from 44 states the previous week. The number of states at the highest level of ILI activity on the CDC’s 1-10 scale dropped from 20 to 11, and those in the high range (8-10) dropped from 26 to 20, data from the CDC’s Outpatient ILI Surveillance Network show.

There was one flu-related pediatric death during the week of March 23 but none reported from earlier weeks, which brings the total to 77 for the 2018-2019 season, the CDC said.

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