If John Nkengasong had followed his youthful impulse to study wildlife conservation, perhaps fewer African species would be threatened today. Instead, the esteemed virologist and public health trailblazer has spent his life protecting people from viruses.

During the Covid-19 pandemic, Nkengasong has been the voice of medical science on the continent, the Anthony Fauci of Africa, whose states have united against the coronavirus...