Abstract
In 2016, the World Health Organization (WHO) announced a global shortage of inactivated poliovirus vaccine that was expected to last until 2020 at least. In response, WHO's Strategic Advisory Group of Experts on Immunization recommended that countries consider a strategic shift to fractional-dose inactivated poliovirus vaccine, which involves a new dosing schedule (i.e. administered at 6 and 14 weeks of age) and has a different mode of delivery than full-dose inactivated poliovirus vaccine (i.e. intradermal rather than intramuscular). Introduction of fractional-dosing requires careful planning and management to ensure adequate vaccine supplies, to prevent wastage, to provide training for health workers, and to ensure accurate record-keeping. In early 2016, given the global vaccine shortage and a limited supply from domestic manufacturers, India's Expert Advisory Group on polio recommended the staggered introduction of fractional-dosing. India was the first country to introduce fractional-dose inactivated poliovirus vaccine into routine immunization, initially in eight states in 2016. Following a rapid assessment of its initial implementation, fractional-dosing was extended and, by June 2017, all Indian states were covered. Here we summarize India's experience with the introduction, discuss the challenges faced and the strategies used to address them, and report on the outcomes achieved. We also describe the lessons learnt, especially managing vaccine supplies and wastage, monitoring and supervision, and training needs. As the use of fractional-dose inactivated poliovirus vaccine is dose-sparing and reduces the cost of the immunization programme, it will remain an important part of India's long-term strategy for polio vaccination.