To stem a growing polio crisis, health officials are accelerating the development of a new oral vaccine with plans for emergency approval and deployment in regions with active polio transmission as early as June 2020. The new vaccine, called nOPV2, might conclusively end the outbreaks, caused by the live virus in the vaccine reverting to a virulent form. But expedited approval means skipping the real-world testing of large clinical trials.
Instead, key questions about the vaccine’s effectiveness will be answered in the field.
“The nOPV strains have been tested in a small number of volunteers and we do not see reversion to neurovirulence,” says Vincent Racaniello, a virologist at Columbia University, “but when they are used for mass immunization of millions of individuals, rare events can become evident.”…
Because of the compressed approval and deployment timeline, nOPV2 may be used in millions of kids beginning in mid-2020….
Nowadays, cases of polio caused by vaccine-derived strains outnumber those caused by the wild virus–and they continue to spread unchecked, most recently from the Phillipines to Malaysia. Vaccine-derived polio threatens as many as 210 million children globally, according to the World Health Organization. Using the reversion-prone Sabin type 2 vaccine to fight outbreaks caused more new outbreaks than it stopped, a virologist at the Centers for Disease Control and Prevention (CDC) told Science earlier this year….