2018 to 2019 vaccine cut influenza A-linked hospitalizations

(HealthDay)—The 2018 to 2019 influenza vaccine effectiveness (VE) was about 40 to 60 percent for reducing pediatric influenza A-associated hospitalizations and emergency department visits, according to a study published online Oct. 5 in Pediatrics.

Angela P. Campbell, M.D., M.P.H., from the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues tested children aged 6 months to 17 years with acute respiratory illness for influenza using molecular assays. Vaccination status was examined based on parental report, state immunization information systems, and/or provider reports. VE was estimated using a test-negative design comparing the odds of vaccination for children testing positive versus negative for influenza.

The researchers found that 13 percent of 1,792 inpatients were influenza-positive: 47, 36, 9, and 7 percent for influenza A(H3N2), A(H1N1)pdm09, A (not subtyped), and B viruses, respectively. Twenty-two percent of the 1,944 children with emergency department visits were positive for influenza: 48, 35, 11, and 5 percent for A(H3N2), A(H1N1)pdm09, A (not subtyped), and B viruses, respectively. VE was 41 percent against any influenza-related hospitalizations: 41 and 47 percent for A(H3N2) and A(H1N1)pdm09, respectively. VE was 51 percent against any influenza-related emergency department visits: 39 and 61 percent against A(H3N2) and A(H1N1)pdm09, respectively.

"The vaccine was ~40 percent effective against A(H3N2)-related hospitalizations and emergency department visits, even in a season when antigenically drifted clade 3C.3a influenza viruses were the predominant circulating A(H3N2) viruses," the authors write.

Several authors disclosed financial ties to the pharmaceutical industry.

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