A study published in Vaccine examined the efficacy of the quadrivalent split-virion inactivated influenza vaccine, IIV4, containing two A strains (H1N1 and H3N2) and B strains from both lineages (Victoria and Yamagata).
The phase III randomized, controlled trial was conducted in Latin America, Asia, Africa and Europe during the 2014-15 and 2015-16 flu seasons in the Northern Hemisphere and the 2014 and 2015 flu seasons in the Southern Hemisphere. Children aged 6 months to 35 months, who had not previously been vaccinated, were divided into four groups receiving two full doses of IIV4, placebo, the licensed trivalent split-virion inactivated vaccine or an investigational trivalent vaccine.
The study included 5,806 participants, and efficacy of IIV4 was demonstrated for 4,980 participants. IIV4 vaccine efficacy was 50.98 percent against influenza caused by any A or B type and 68.4 percent against influenza caused by vaccine-like strains.