Despite high coverage rates of polio vaccine in the Islamic Republic of Iran, the seroconversion rates of
infants may be inadequate. This study measured seroprevalence of antibodies against poliovirus serotypes 1 to 3 (PV1,
PV2 and PV3) in 7-month-old infants who had received at least 4 doses of trivalent oral polio vaccine. A serosurvey
was conducted in 2010 in rural areas of Chabahar, Sistan-va-Baluchestan province. Using cluster sampling, 72 eligible
infants were tested for antibody against the 3 poliovirus serotypes according to WHO guidelines. Antibody titres = 1:10
were considered positive. The seropositive rates for antibody against PV1, PV2 and PV3 were 84.7%, 95.8% and 70.8%
respectively. Only 63.9% of participants were seropositive for antibodies against all 3 poliovirus serotypes. Except
for PV2, the seroprevalence of antibody against the other 2 poliovirus serotypes, especially PV3, was unsatisfactory.