Researchers conducted a test of the new four-strain influenza vaccine, available for the first time this year, to determine how well it protected against the flu in young children.
The four strain vaccine, which protects against four types of influenza–two viruses from the A class and two from the B class–does as good a job of protecting against flu than the three-strain shot, but is better at preventing moderate to severe disease than the traditional immunization.
The international group of researchers, who described their findings in a report published in the New England Journal of Medicine, attributed the four-strain, or quadrivalent vaccine’s effectiveness to the fact that it contained both circulating B types of influenza. In previous years, in which only one of the B strains was included, the immunization had a 50-50 chance of being mismatched to the circulating virus, making it less effective.
The scientists tested the quadrivalent flu vaccine in 2,379 children ages three to eight in Bangladesh, the Dominican Republic, Honduras, Lebanon, Panama, the Philippines, Thailand and Turkey and compared their rates of flu infection to a control group of 2398 children who received a hepatitis A vaccine. The study was sponsored by GlaxoSmithKline, which donated both vaccines for the trial.
Compared to the control group, the four strain vaccine was 55% effective in protecting against flu. That’s similar to the efficacy of the three strain shots, but, the research team found, the quadrivalent shot was 70% effective in preventing more serious cases of the flu; most of the children who did get sick after getting vaccinated only had mild symptoms. The four-strain shot also resulted in 69% fewer medical visits, 75% fewer hospitalizations, 77% fewer absences from school, and 61% fewer parent absences from work.
That’s an important benefit, since flu can result in lost school days for children and lower productivity for adults. “The efficacy of the vaccine was higher against moderate-to-severe disease–a potentially important end point associated with the highest clinical, social, and economic burden–than against illness of any severity,” the authors conclude.