Announcement of new polio vaccines has once again raised hopes of eradicating polio. But the ongoing difficulties of their predecessors provide a cautionary tale, writes Robert Fortner
In June 2023, a research article in Nature heralded new, “more stable” versions of the vaccines against two of the three types of poliovirus (types 1 and 3).1 “Super-engineered polio vaccines created to help end polio,” read a BBC headline.2 “Polio endgame finish is in sight,”3 added a Nature news article.3 The backdrop, however, is a little muddier.
A similar fanfare had greeted the first of this new generation of oral polio vaccines in 2021. Novel oral polio vaccine type 2 (nOPV2) targets type 2 polio and went straight into widespread use. But it remains far from clear how well nOPV2 works.
Before it was approved for emergency use, scientists warned that nOPV2 would not solve the problem set for it: to stamp out vaccine-derived polio. So far, it has not done so. Instead there are unanswered questions about the vaccine’s performance, whether the decision to rely on it was right, and whether there’s a viable path to the dream of global eradication even with a full suite of modernised vaccines.
The quest to rid the world of polio began in earnest in the late 1980s with the formation of the Global Polio Eradication Initiative (GPEI), a public-private partnership led by the World Health Organization together with Unicef, the US Centers for Disease Control and Prevention (CDC), and Rotary International. They were joined later by the Bill and Melinda Gates Foundation and the global vaccine alliance Gavi. Just one disease—smallpox—has been eradicated globally; attempts have also been made to eradicate malaria and guinea worm.
Wild (naturally occurring) polio has been brought close to oblivion, restricted to Afghanistan and Pakistan …