Pfizer’s vaccine takes a “very large” hit from omicron—but boosters help

A double dose of the Pfizer-BioNTech covid-19 vaccine can’t stop the omicron virus, according to labs tests done in in South Africa and Germany, and either a booster or a new vaccine will be needed.  The omicron variant was detected in South Africa last month, and because it contains a large number of genetic changes,…