The research, which has yet to be peer-reviewed, found that people who got COVID-19 three weeks after receiving one dose of either the Pfizer-BioNTech or AstraZeneca vaccines were between 38 percent and 49 percent less likely to give the virus to those in their household, compared to those who didn’t receive any vaccine dose.

Public Health England analyzed more than 57,000 contacts from 24,000 households in which a person who had received a vaccine dose tested positive for the virus and compared it with almost 1 million contacts of cases among unvaccinated people. 

Cases among household contacts were considered secondary cases if they received a positive COVID-19 test two to 14 days after the initial case. 

The researchers found protection was present about 14 days after vaccination and remained steady despite the different ages of cases or contact. The measured protection is in addition to the 60 percent to 65 percent decreased risk of the vaccinated person developing symptomatic COVID-19 four weeks after one dose. 

Researchers said the results would likely be similar in other high-risk transmission locations besides households, such as shared accommodations and prisons.

British Health Secretary Matt Hancock called the study “terrific news,” saying, “We already know vaccines save lives and this study is the most comprehensive real-world data showing they also cut transmission of this deadly virus.” ...