Vaccines are the best cost-benefit tools to control and eradicate infectious diseases. The live smallpox vaccination, called variolation, was the injection of the homologous virus and this promoted self-healing local lesions that guaranteed strong and long-lasting protection. However, since 3% of these variolations caused cases of smallpox in the vaccinated individuals, it was considered unsafe and was discontinued.
Clarisa B. Palatnik-de-Sousa (Institute of Microbiology Paulo de Góes, Federal University of Rio de Janeiro (UFRJ), Rio de Janeiro, Brazil)
Clarisa B. Palatnik-de-Sousa (Institute for Research in Immunology, Faculty of Medicine, University of São Paulo (USP), São Paulo, Brazil)