Polio vaccines: hope, hype, and history repeating?

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.