CDC: 2015-2016 Flu Season Milder Than Previous 3 Seasons

Influenza activity in the 2015-2016 flu season peaked later and was milder overall than the previous 3 seasons, according to a report from the CDC.

Overall, A(H1N1)pdm09 was the predominant circulating strain, accounting for half of detections in individuals aged 5 to 24 and 65 years old and older, and 69% and 67% in individuals aged 0 to 4 and 25 to 64, respectively. The majority of circulating strains matched the components of the 2015-2016 Northern Hemisphere influenza vaccine.
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Cumulative hospitalization rates per 100,000 were 31.3 for all age groups, 41.8 for 0 to 4 years, 9.7 for 5 to 17 years, 16.8 for 18 to 49 years, 45.2 for 50 to 64 years, and 84.8 for 65 years and older.

The Food and Drug Administration has recommended that the 2016-2017 influenza vaccine feature a different composition, based on global influenza surveillance, genetic and antigenic characterization, antiviral susceptibility, and availability of vaccine viruses.

“Testing for seasonal influenza viruses and monitoring for novel influenza A virus infections should continue throughout the summer. Although summer influenza activity in the United States typically is low, influenza cases and outbreaks have occurred during summer months, and clinicians should remain vigilant in considering influenza in the differential diagnosis of summer respiratory illnesses.”

—Michael Potts

Reference:

Davlin SL, Blanton L, Kniss K, et al. Influenza activity — United States, 2015–16 season and composition of the 2016–17 influenza vaccine. Morb Mortal Wkly Rep. 2016;65(22):567-575.