Assessment of cold-chain maintenance in vaccine carriers during Pulse Polio National Immunization Day in a rural block of India.

India was certified polio free on 27 March 2014. Supplementary immunization activities, in the form of national immunization days, is one of the core strategies for eradication, where oral polio vaccine is administered to children aged under 5 years throughout the country. Oral polio vaccine is heat sensitive and requires maintenance of a stringent cold chain. Therefore, vaccine carriers with ice packs are used in the Pulse Polio Immunization (PPI) programme. This study assessed whether the cold chain is maintained during National Immunization Day in Beed district. A cross-sectional study was conducted at six randomly selected booths, one each from six primary health centres in Georai block of Beed district in Maharashtra. Electronic data loggers, configured to measure half-hourly temperatures, were kept in vaccine carriers throughout the day of PPI. The vaccine carrier temperature was below 8 °C at all six booths; minimum temperature recorded was -9.5 °C, while the maximum was 4.5 °C. The vaccine vial monitor did not reach discard point in any booth. A vaccine carrier with four ice packs very effectively maintains the cold chain required for oral polio vaccine.