New data presented to ACIP indicates this year’s influenza vaccine provided fairly strong levels of protection.
According to the data, the vaccine’s effectiveness ranged from approximately 45% to 55% depending on the age group and parameters studied, such as hospitalization and protection against any infection.
The data also showed that influenza A/H3N2 viruses were prevalent this season. The levels of protection achieved with this year’s influenza vaccine were higher compared with those of previous years when H3 viruses were predominant.
About 75% of viruses studied were H3N2 viruses. The degree of protection afforded by the vaccine appeared to be consistent based on 3 vaccine effectiveness networks used by CDC as well as 2 studies by researchers at Wisconsin’s Marshfield Clinic Research Institute.
The Marshfield studies, backed by influenza vaccine maker CSL Seqirus and CDC, estimated vaccine effectiveness in individuals ages 6 months to 64 years to be 54%. A second study comprising children 1–17 years old indicated vaccine effectiveness of 71% against symptomatic influenza infection.