The announcement this week that a cheap, easy-to-make coronavirus vaccine appeared to be up to 90 percent effective was greeted with jubilation. “Get yourself a vaccaccino,” a British tabloid celebrated, noting that the vaccine, developed by AstraZeneca and the University of Oxford, costs less than a cup of coffee.But since unveiling the preliminary results, AstraZeneca has acknowledged a key mistake in the vaccine dosage received by some study participants, adding to questions about whether the vaccine’s apparently spectacular efficacy will hold up under additional testing.Scientists and industry experts said the error and a series of other irregularities and …
