The World Health Organization (WHO) has quality-assured (prequalified) the novel type 2 oral polio vaccine (nOPV2) after 3 years of being granted Emergency Use Listing (EUL). The vaccine was developed with contributions from scientists at the UK Medicines and Healthcare products Regulatory Agency (MHRA).

The WHO decision follows the delivery of 950 million doses worldwide and scrutiny of the results in immunized populations, affirming the vaccine’s safety and efficacy. 

The nOPV2 is a modified version of the oral polio vaccine (OPV) that specifically targets poliovirus type 2. It was developed to mitigate the risk of vaccine-derived outbreaks, which can occur when the weakened virus in the vaccine circulates among under-immunized populations and regains the ability to cause paralysis. It maintains effectiveness against polio while reducing the potential for the virus to mutate and regain virulence, making it a safer option for widespread vaccination campaigns, especially in regions where polio remains a threat.

Genetic modifications to the vaccine, for example, a stabilized RNA stem-loop structure in the 5′ noncoding region that is the major determinant of OPV2 attenuation, were tested through a number of pre-clinical methods (serial passaging, cell culture assays used to estimate temperature sensitivity, testing in transgenic mice models, etc.) before initiating clinical development.

The nOPV2 serves as a crucial shield for children against polio, and its prequalification status by the WHO streamlines access for WHO member countries without the stringent readiness criteria previously mandated under the EUL. 

Prequalification guarantees extended and widespread availability for global organizations to supply and distribute the nOPV2 in developing nations. 

Poliomyelitis, transmitted mainly through contaminated food and water, particularly threatens infants and young children, potentially leading to severe paralysis or fatality. 

The OPVs, including nOPV2, have substantially curbed polio cases globally. They do not require stringent cold storage, facilitating immunization in remote areas. 

Three years ago, amid mounting concerns about vaccine-derived outbreaks in Asia and Africa, the nOPV2 became the first vaccine to gain WHO EUL , paving the way for its prequalification today. 

The decision signifies a pivotal step forward in fortifying global immunity against polio and reaffirms the collective commitment to ensure children worldwide receive safer and more accessible polio vaccines.