Influenza tetravalent vaccines in national immunization programs for Latin-American countries

Since 2012-2013 influenza season, World Health Organization (who) recommends the formulation of tetravalent vaccines. Globally, many countries already use tetravalent vaccines in their national immunization programs, while in Latin America only a small number. Two Influenza b lineages co-circulate, their epidemiological behavior is unpredictable. On average they represent 22.6% of influenza cases and more than 50% in predominant seasons. The lack of concordance between recommended and circulating strains was 25 and 32% in the 2010-2017 and 2000-2013 seasons, respectively. There are no clinical differences between influenza A and B. It occurs more frequently from five to 19 years of age. Influenza b has a higher proportion of attributable deaths than influenza a (1.1 vs. 0.4%), or 2.65 (95% ci 1.18-5.94). A greater number of hospitalizations when the strains mismatch (46.3 vs. 28.5%; p <.0001). Different evaluations have demonstrated its cost effectiveness. The compilation of this information supports the use of quadrivalent vaccines in Latin American countries