Researchers urge delay in administering Pfizer vaccine's second dose

Researchers on Wednesday urged governments to delay administering the second dose of Pfizer Inc’s Covid-19 vaccine, which they said had an efficacy of 92.6 percent after the first dose.

The researchers, Danuta Skowronski and Gaston De Serres, said their findings were derived from Pfizer’s documents submitted to the US Food and Drug Administration...