Johnson & Johnson one-dose vaccine not as effective as others

Johnson & Johnson’s long-awaited vaccine appears to protect against COVID-19 with just one shot – not as strong as some two-shot rivals but still potentially helpful for a world in dire need of more doses. J&J said Friday that in the US and seven other countries, the single-shot vaccine was 66 percent effective overall at preventing moderate to severe illness, and much more protective – 85 percent – against the most serious symptoms. There was some geographic variation. The vaccine worked better in the US — 72 percent effective against moderate to severe COVID-19 – compared with 57 percent in South Africa, where it was up against an easier-to-spread mutated virus. “Gambling on one...