Another covid-19 vaccine joins the party

ON NOVEMBER 23RD, for the third Monday in a row, the results of an anti-covid vaccine were announced. This time the protagonists were AstraZeneca, a British-Swedish pharmaceutical company, and Oxford University. They reported their vaccine to be 70% effective. But doubts have since arisen about the conduct of the trials which arrived at this figure.

The consortium’s researchers estimated their vaccine’s efficacy from interim data collected by trials in Britain and Brazil. These involve more than 23,000 volunteers, half of whom have received the vaccine and the other half a placebo of one sort or another. Like the previous offerings (one from a partnership between Pfizer, a big American pharma company, and BioNTech, a small German one; the second from another American firm, Moderna), the AstraZeneca-Oxford inoculation is administered in two jabs. Of those given it, none has been admitted to hospital with covid-19, nor suffered a severe case of it. The researchers from AstraZeneca and Oxford also say that their vaccine may reduce passage of the virus between people—a property not yet established for either of the other two. An ideal vaccine needs to break the chain of transmission, as well as stopping recipients from falling ill, so this claim is important.