Volume 26, Number 4—April 2020
Tzu-Yu Weng, Hua Yen, Kutub Mahmood, Javier Martin, and Min-Shi Lee
National Health Research Institutes, Zhunan, Taiwan (T.-Y. Weng, H. Yen, M.-S. Lee); Center for Vaccine Innovation and Access, PATH, Seattle, Washington, USA (K. Mahmood); National Institute for Biological Standard and Control, Potters Bar, UK (J. Martin)
The Asia-Pacific Network for Enterovirus Surveillance in the National Health Research Institutes hosted a workshop on May 2, 2019, to discuss the harmonization of 2 licensed enterovirus vaccines, poliovirus and enterovirus A71 (EV-A71), especially regarding the standardization of vaccine antigens (Appendix). Speakers from the UK National Institute for Biologic Standard and Control (NIBSC), US PATH, industries, and regulatory agencies shared their experiences.
Sabin strain–derived live-attenuated oral poliovirus vaccines (OPV) and wild strain–derived inactivated poliovirus vaccines (IPV) have been widely used. Since wild-type 2 poliovirus was eradicated, bivalent OPV (only type 1 and 3) replaced trivalent OPV. Wild-type 3 is almost eradicated, and major efforts are under way to eradicate type 1. In addition, wild strains are not feasible to produce conventional IPV (cIPV) after wild polioviruses are eradicated. Therefore, the World Health Organization (WHO) recommends the development of Sabin strain–derived IPV (sIPV) for the endgame plan of global poliovirus eradication programs. Because WHO international standard (IS) antigen for quantifying cIPV antigens could not be effectively used to quantify sIPV, new reagents based on sIPV need to be established.
Three EV-A71 vaccines have been licensed in China, and 2 EV-A71 vaccine candidates were evaluated in phase III trials in Taiwan. Experience with IPV indicates that establishing WHO IS antigens is critical for global harmonization of EV-A71 vaccines. Thus, NIBSC and the China National Institute of Food and Drug Control (NIFDC) coordinated an international study for the first IS antigen of EV-A71 vaccines. Some participants in the international study shared their results in the workshop. This report summarizes outcomes of presentations and discussion.