CDC Releases Update on Influenza Virus During 2016-2017 Season

The CDC has released trends on influenza activity in the United States during the 2016-2017 flu season. This data is updated yearly to consider new strains of the virus circulating in society and the overall length of the season.

The season lasted from October 2, 2016, to May 20, 2017, with activity that remained low through November and increased in December. The number of patients infected with the virus peaked in February. The data were obtained from public health and clinical laboratories located in all 50 states, Puerto Rico, and the District of Columbia.

Approximately 70% of patients tested positive for influenza A viruses and 30% tested positive for influenza B viruses.

Influenza A was the predominant virus among all age groups; however, influenza B cases were highest among individuals aged 5 to 24 years and accounted for 28% of reported viruses for that age group, according to the report. Three novel influenza A viruses were reported to the CDC, however, none of these patients were hospitalized and all recovered.

Several medical conditions can increase an individuals risk for contracting influenza. These include cardiovascular disease, metabolic disorders, obesity, asthma, neurologic disorders, and chronic lung disease. Many children hospitalized had at least 1 of these underlying medical conditions.

A total of 98 laboratory-confirmed influenza-influenced deaths occurred among children, 46 of which were associated with influenza A, 34 with influenza B, 3 with influenza A(H1N1)pdm09 virus, and 14 with influenza A for which no subtyping was done. Death among adults also peaked twice this year during the weeks ending January 21, 2017, and February 25, 2017.

The US Influenza Vaccine Effectiveness network collected data that showed a 42% decrease in risk for contracting the virus.

Reference

Blanton L, Alabi N, Mustaquim D, et al. Update: Influenza activity in the United States during the 2016—17 season and composition of the 2017–18 influenza vaccine. Morb Mortal Wkly Rep. 2017;66:668—676. DOI: http://dx.doi.org/10.15585/mmwr.mm6625a3.