A second dose of inactivated polio vaccine (IPV) has been added to the routine immunization schedule in Tajikistan. Tajik children will now receive two doses of a vaccine that protects them from all three types of poliovirus, including type 2, which is not contained in the oral polio vaccine.
Effective immediately, in addition to receiving the vaccine at three months, children will receive another dose of IPV at nine months of age. This provides additional immunity against poliovirus type 2, which has been eradicated globally and subsequently removed from the oral polio vaccine, but which can emerge in communities with low immunization rates in the form of vaccine-derived poliovirus.
Polio is a highly infectious disease that mainly affects young children and can cause disability or death. Introduction of the second dose of IPV by the Ministry of Health and Social Protection of Population of the Republic of Tajikistan follows the advice of the WHO Strategic Advisory Group of Experts on Immunization (SAGE) and the Tajikistan National Immunization Technical Advisory Group (NITAG). Tajikistan introduced the first dose of IPV in 2018. Adding a second dose of IPV to the immunization schedule is crucial to prevent any potential future outbreaks of polio caused by vaccine-derived poliovirus type 2.
Recent outbreak of vaccine-derived poliovirus type 2
While the European Region was declared polio-free in 2002, importations of the virus continue to occur. Tajikistan is particularly susceptible to importation. It shares a long border with Afghanistan and is located close to Pakistan, and both of these countries remain endemic for wild poliovirus type 1 and have been affected by circulating vaccine-derived poliovirus type 2. The most recent polio outbreak in Tajikistan was first detected in January 2021 and linked to an imported type 2 vaccine-derived poliovirus strain circulating in Pakistan at the time. Extensive immunization efforts began in February 2021, and the outbreak was officially closed in April 2022.
WHO, with support from GAVI, the Vaccine Alliance, and the United Nations Children’s Fund (UNICEF), provides extensive support to the Government of Tajikistan to carry out effective immunization campaigns to protect the population from polio and strengthen monitoring and surveillance of polio. These efforts are part of the Global Polio Eradication Initiative (GPEI) – a public–private partnership that aims to eradicate polio worldwide.