In Mexico, the majority of influenza vaccinations are trivalent, comprising two influenza A strains and a single B strain. Quadrivalent influenza vaccinations (QIVs) provide extra protection by adding a B strain that covers both co-circulating B lineages. Researchers evaluated how a transition to QIV would have influenced influenza-related health outcomes in Mexico from 2010/2011 to 2015/2016 influenza seasons, and projected the monetary effect of adopting QIV in Mexico’s national vaccination programme from 2016/2017 to 2020/2021. They utilised a budget effect model based on retrospective attack rates and anticipated future vaccination coverage for the prospective estimation. A transition to QIV would have avoided 270,596 extra influenza cases, 102,000 general practitioner visits, 140,062 days of absenteeism, 3,323 hospitalizations, and 312 fatalities between 2010/2011 and 2015/2016, saving Mex$214 million in third-party payer expenditures. A transition to QIV was predicted to avoid an extra 225,497 influenza cases, 85,000 general practitioner visits, 116,718 days of absenteeism, 2,769 hospitalizations, and 260 fatalities in the prospective study.

The benefit and expenses saved with QIV were sensitive to the distribution of influenza A vs. B cases and trivalent vaccination efficacy against the mismatched B strain when compared to the trivalent vaccine. These findings indicate that switching to QIV in Mexico would benefit both healthcare professionals and society by lowering influenza cases, morbidity, and mortality, as well as the related use of medical resources.