- A single dose of the COVID-19 vaccine made by either Pfizer or AstraZeneca cuts a person’s risk of transmitting SARS-CoV-2 to their closest contacts by as much as half, according to an analysis of more than 365,000 households in the United Kingdom. https://khub.net/documents/135939561/390853656/impact+of+vaccination+on+household+transmission+of+sars-cov-2+in+england.pdf/35bf4bb1-6ade-d3eb-a39e-9c9b25a8122a?t=1619551571214 184 comments science