In an attempt to implement a global eradication initiative of the polio virus, the first type 2 novel oral polio vaccine (nOPV2) became the first vaccine to be authorised for use under the WHO Emergency Use Listing (EUL) apparatus. However, the current nOPV2 vaccine presents an increased risk of type 2 circulating vaccine-derived polioviruses (cVDPV2), especially in communities with low immunization rates. African countries continue to be amongst the most impacted by this potentially lethal virus. Consequentially, the use of the nOPV2 is currently restricted and SAGE recommended that an independent safety monitoring group be established (GACVS) and maintain thorough safety observations during the entire period of the EUL.
Under the current EUL, there is a 2 phase roll out of the nOPV2 vaccine. With phase 1, countries must first meet stringent initial use criteria and verification requirements including continuous flaccid paralysis (AFP) monitoring to attain approval for use. Following this, phase 2 supports the use of the nOPV2 vaccine as a standard response for cVDPV2 outbreaks.
Following rigorous safety criteria, as of 9 June 2021, 7 countries have received approval for use authorisation of the nOPV2 vaccine and 25 countries are still pending. Majority of the nOPV2 doses thus far have been administered in Nigeria (17 899 130) and Liberia (853 279) amongst children 5 years of age and under in the form of two oral vaccine drops. GACVS is working closely with the Liberian and Nigerian governments to implement AESI surveillance and ongoing AFP data to ensure the safety and effectiveness of the vaccine in preventing polio infection. Current preliminary data analysis did not indicate elevated safety issues associated with the nOPV2 vaccine, however GACVS members have stressed that prolonged, comprehensive surveillance is imperative to signal imminent safety concerns.
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WHO: Safety profile of nOPV2 vaccine