A second vaccine against covid-19 arrives

WAITING FOR a breakthrough in the fight against covid-19 has been a bit like waiting for a bus to arrive. After almost a year of watch-checking and neck-craning, two come along at once. First, on November 9th, Pfizer, an American pharma giant and BioNTech, a German minnow, announced that they had jointly developed an effective vaccine for the illness. They were followed, on November 16th, by Moderna, an American biotech firm.Moderna says its offering is 94.5% effective. Pfizer says the efficacy of its is 95%. Moderna’s figure is an estimate based on a peek at data being gathered in a continuing trial involving 30,000 volunteers. Pfizer’s comes from the final analysis of a trial involving 43,000 people, in which 170 cases of covid-19 were seen. Of these, 162 were in the placebo arm (ie, those involved had received dummy injections).