When covid-19 vaccines meet the new variants of the virus

ON FEBRUARY 1ST researchers around the world saw the tweet for which they had been waiting: “We say with caution, the magic has started”. Eran Segal, a scientist at the Weizmann Institute, had been posting regular updates on the course of Israel’s covid-19 epidemic since its mass vaccination campaign had begun six weeks earlier. By February 1st he was seeing the number of hospitalisations dropping significantly among the over-60s—a cohort in which the number vaccinated had reached 70%, seen as a crucial level, three weeks before. After an expected but still somewhat nail-biting lag, the vaccine was doing its thing.