The latest blow to AstraZeneca’s tortured effort to bring a Covid-19 vaccine to the world arrived by way of a terse statement released on Tuesday at 22 minutes past midnight in Washington.

In an unprecedented late-night intervention, the National Institutes of Health warned that an independent board of experts overseeing a large US study of the vaccine had “expressed concern that AstraZeneca may have included outdated information” when it announced results from the trial in a press release on Monday...