Early on in the pandemic, many of us hoped India would help vaccinate the world. The country’s pharmaceutical sector, dominated by companies capable of churning out generic medicines in vast quantities, looked like the obvious location for vaccine production at the scale needed to inoculate the developing world.

That hasn’t worked out, partly because the Indian government restricted vaccine exports after the Delta variant emerged there, but also because of the unexpected and early success of the mRNA-based shots from Moderna and Pfizer. These came on the market early and set high standards for efficacy against the original variant of the virus. But they were remarkably ill-suited for production and distribution in the emerging world. They need to be stored at untenably low temperatures and their novel production process isn’t easy to replicate...