Study finds COVID-19 vaccine may reduce virus transmission What to expect after getting a COVID-19 vaccine By Associated Press | February 3, 2021 at 11:09 AM CST - Updated February 3 at 9:18 PM (AP) - AstraZeneca’s COVID-19 vaccine shows a hint that it may 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.