Compared with placebo, vaccinating children aged 6 to 35 months with a quadrivalent split-virion inactivated influenza vaccine (IIV4) reduced severe influenza outcomes as well as parental absenteeism from work and influenza-associated healthcare use, according to a study published in Vaccine.

This Northern and Southern Hemisphere, multi-season, placebo-controlled, randomized phase III trial was designed to examine the vaccine efficacy of IIV4 in healthy children aged 6 to 35 months and to determine the relative risk for associated healthcare use (outpatient visits and hospitalization, both outpatient and inpatient), severe outcomes, antibiotic use, and parental absenteeism associated with laboratory-confirmed cases of influenza.

Vaccine efficacy to prevent laboratory-confirmed influenza (A or B strain) was 54.76% (95% CI, 40.24%-66.03%) for participants aged 6 to 23 months and 46.91% (95% CI, 23.57%-63.53%) for participants aged 24 to 35 months. Vaccine efficacy within vaccine-similar strains was 74.51% (95% CI, 53.55%-86.91%) for participants aged 6 to 23 months and 59.78% (95% CI, 19.11%-81.25%) for participants aged 24 to 35 months. Compared with placebo, IIV4 reduced the risk for acute otitis media by 31.28% (95% CI, 8.96%-89.34%), acute lower respiratory infection by 21.76% (95% CI, 6.46%-58.51%), healthcare medical visits by 40.80% (95% CI, 29.62%-55.59%), parental absenteeism from work by 29.71% (95% CI, 11.66%-67.23%), and antibiotic use by 39.20% (95% CI, 26.89%-56.24%).

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Study investigators concluded that “in children aged 6–35 months, vaccination with two full doses of IIV4 can protect against influenza and reduces the frequency of severe outcomes of influenza. IIV4 thereby helps reduce the burden of influenza in young children, their parents, and the healthcare system.”

This study was sponsored by Sanofi Pasteur. The sponsor participated in study design, data collection, analysis and interpretation; the writing of the report; and the decision to submit for publication. All authors are employees of the study sponsor.


Pepin S, Samson, SI, Alvarez, FP, Dupuy M, Gresset-Bourgeois V, De Bruijn I. Impact of a quadrivalent inactivated influenza vaccine on influenza-associated complications and health care use in children aged 6 to 35 months: analysis of data from a phase III trial in the Northern and Southern Hemispheres [published online February 8, 2019]. Vaccine. doi: 10.1016/j.vaccine.2019.01.059

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This article originally appeared on Infectious Disease Advisor