Background: The effect of vaccination against the influenza virus on the mortality due to cardiovascular diseases (CVD) remains controversial.
Objective: To analyze the mortality by CVD before and after the start of the vaccination against the Influenza virus in the city of Sao Paulo, Brazil.
Methods: We analyzed the mortality due to ischemic heart diseases (IHD), cerebrovascular diseases (CbVD) and external causes (EC) in the population of the metropolitan region of the city of Sao Paulo, Brazil, aged > or = 60 years, before and after the start of the vaccination program against Influenza. The population estimates and mortality data were obtained, respectively, from the Brazilian Institute of Geography and Statistics (IBGE; www.ibge.gov.br) and from the Brazilian Ministry of Health (www.datasus.gov.br) for the period between 1980 and 2006. The risk of death was adjusted by the direct method, using the 1960 world standard population.
Results: The comparisons between the inclinations of the regression lines were similar for CbVD (p = 0.931) and EC (p = 0.941); however, for IHD (p = 0.022), a significant decrease was observed in the regression line of the post-vaccination period, when compared to the pre-vaccination period. A change in the tendency towards mortality after 1996 was significant only for the IHD (p = 0.022), remaining unaltered for the CbVD (p = 0.931) and EC (p = 0.941).
Conclusion: The vaccination against the Influenza virus was associated with a significant decrease in the mortality due to IHD.