In the race for a Covid-19 vaccine, here come the tortoises

The race is not always to the swift, as the cocky hare learned in Aesop’s classic fable, “The Hare and the Tortoise.” Those handicapping the so-called competition to develop Covid-19 vaccines would do well to keep an eye on the slower runners in this pursuit. Corporate giants Sanofi and Merck, which got a relatively late start in developing Covid-19 vaccines, may seem far behind the frontrunners. But experts say they also have such deep experience developing and testing vaccine candidates, and producing vaccine at commercial scale, that both could well close the gap considerably in the months ahead. Each is developing two vaccines, in partnership with others.