Although wild poliovirus type 3 has not been detected globally for 7 years, the number of wild type 1 cases increased from 33 in 2018 to 173 in 2019. In response, a modified oral vaccine is being developed, according to Stephen Cochi, MD, of the Centers for Disease Control and Prevention’s Center for Global Health.
Several factors, including a Taliban ban on house-to-house vaccination in Afghanistan and a delay of large-scale vaccinations in Pakistan contributed to the surge in polio infections, Dr. Cochi said in a presentation at the February meeting of the CDC’s Advisory Committee on Immunization Practices (ACIP).
In addition, circulating vaccine-derived polioviruses (cVDPV) outbreaks have occurred in multiple countries including sub-Saharan Africa, China, Pakistan, and the Philippines. These outbreaks threaten the success of the bivalent oral polio vaccine introduced in April 2016 in 155 countries, Dr. Cochi said.
Outbreaks tend to occur just outside targeted areas for campaigns, caused by decreasing population immunity, he said.
The novel OPV2 (nOPV2) is a genetic modification of the existing OPV2 vaccine designed to improve genetic stability, Dr. Cochi explained. The modifications would “decrease the risk of seeding new cVDPVs and the risk of vaccine-associated paralytic poliomyelitis (VAPP),” he said.
The Emergency Use Listing (EUL) was developed by the World Health Organization in response to the Ebola virus outbreak in 2014-2016 and is the fastest way to obtain regulatory review and approval of drug products, said Dr. Cochi.
A pilot plant has been established in Indonesia, and upon EUL approval, 4-8 million doses of the nOPV2 should be available for use in the second quarter of 2020, he concluded.
Dr. Cochi had no relevant financial conflicts to disclose.