Vital Signs Blog

H1N1 drives majority of hospitalizations in latest flu season

A strong resurgence of the H1N1 strain of flu virus this season contributed to nearly 10,000 hospitalizations, according to federal health officials Thursday. Non-elderly adults were among the most affected populations.

More than 9,500 influenza-related hospitalizations were reported this season, according to the findings of the Center for Disease Control and Prevention's latest Morbidity and Mortality weekly Report, with 57% of cases occurring among those between the ages of 18 and 64. Among those hospitalized, 88% reportedly had the deadly H1N1 virus, the same flu strain that the World Health Organization initially estimated was responsible for 18,000 deaths worldwide during 2009's flu pandemic. However, the H1N1 strain has since been attributed to as many as 200,000 deaths worldwide, according to the findings of a study published in the journal PLOS Medicine in November.

Flu cases reached their peak between late December 2013 and late January, with the death rate from flu and pneumonia accounting for 8.7% of all deaths reported during the week ending January 25. A total of 96 pediatric deaths were reported in 30 states, New York City and Chicago. Flu activity within states was at its highest in mid-January, when the illness was reported to be widespread in 41 states.

The CDC has estimated that influenza vaccines used this season has been effective in preventing a further spread of illness, reducing the risk of infection by 60%, according to a MMWR report released in February.

According to recommendations from the Food and Drug Administration's Vaccines and Related Biological Products Advisory Committee, the same types of vaccines that were used for this season should be effective for next season as well, based on surveillance data.

Follow Steven Ross Johnson on Twitter: @MHsjohnson


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