Risk of polio reintroduction to border regions of Islamic Republic of Iran: seroprevalence study of children with at least 5 doses of oral polio vaccine

Movements of populations from countries where polio has not been eradicated is a concern in the Islamic Republic of Iran. A cross-sectional, community-based study was implemented in 2010 in 2 districts in Sistan-va-Baluchestan Province near the south-east border. The aim was to determine the seroprevalence of antibodies in children aged 20 (± 2) months who had received at least 5 doses of trivalent oral polio vaccine. Using cluster sampling, 365 children were enrolled for serological testing. Antibody titres ≥ 1:10 were considered positive. Seropositive rates for antibody against poliovirus serotypes 1, 2 and 3 were 94.1%, 96.7% and 78.3% respectively. The lowest seropositive rate was for antibody against polio serotype 3 (PV3) among boys (58.3%). Exclusive breastfeeding showed a direct relationship with antibody response to PV3 (OR = 2.0; 95% CI: 1.1-3.6). Improving community protection against PV3 is an urgent programme priority.