Monitoring of poliovirus neutralizing antibodies in São Paulo State, Brazil.

As the world envisions poliomyelitis eradication, objective parameters are needed to ascertain whether immunocompetence against the virus provided by vaccine campaigns has been attained. The presence of neutralizing antibodies is considered a surrogate marker of protective immune response to the agent. Neutralization of three poliovirus serotypes were evaluated in a total of 411 sera samples collected from 1999 to 2005 in São Paulo State, Brazil. Antibody titres >/=1:8 were presented at 88.1% (362/411), 88.8% (365/411) and 61.6% (253/411) of samples for 1, 2 and 3 serotypes, respectively. Evaluation of poliovirus immune status may be a useful tool to support decisions concerning polio vaccine policy.