Study finds COVID-19 vaccine may reduce virus transmission

AstraZeneca’s COVID-19 vaccine does more than prevent people from falling seriously ill — it appears to reduce transmission of the virus and offers strong protection for three months on just a single dose, researchers said Wednesday in an encouraging turn in the campaign to suppress the outbreak.

The preliminary findings from Oxford University, a co-developer of the vaccine, could vindicate the British government’s controversial strategy of delaying the second shot for up to 12 weeks so that more people can be quickly given a first dose. Up to now, the recommended time between doses has been four weeks.

The research could also bring scientists closer to an answer to one of the big questions about the vaccination drive: Will the vaccines actually curb the spread of the coronavirus?

It’s not clear what implications, if any, the findings might have for the two other major vaccines being used in the West, Pfizer’s and Moderna’s.

In the United States, Dr. Anthony Fauci, the nation’s top infectious disease expert, dismissed the idea of deliberately delaying second shots, saying the U.S. will “go by the science” and data from the clinical trials. The two doses of the Pifzer and Moderna vaccines are supposed to be given three and four weeks apart.

Still, the research appears to be good news in the desperate effort to arrest the spread of the virus and also suggests a way to ease vaccine shortages and get shots into more arms more quickly.

The makers of all three vaccines have said that their shots proved to be anywhere from 70% to 95% effective in clinical trials in protecting people from illness caused by the virus. But it was unclear whether the vaccines could also suppress transmission of the virus — that is, whether someone inoculated could still acquire the virus without getting sick and spread it...