One dose of the Pfizer or AstraZeneca vaccines reduces the chances of someone infected with coronavirus from spreading it to other household members by up to 50 percent, according to an English study published on Wednesday. 

A man receives his Covid-19 vaccination at the John Scott Vaccination Centre in Green Lanes, north London, the UK, on March 21. Photo: VCG

The Public Health England (PHE) research found that those who became infected three weeks after receiving their first jab were between 38 and 49 percent less likely to pass the virus on to their household contacts than those who were unvaccinated.

"This is terrific news - 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," said British Health Secretary Matt Hancock.

"It further reinforces that vaccines are the best way out of this pandemic as they protect you and they may prevent you from unknowingly infecting someone in your household," he added. 

The study drew data from over 57,000 contacts in 24,000 households in which there was a lab-confirmed case that had received a vaccination, compared with nearly 1 million contacts of unvaccinated cases. 

Previous studies have already shown that being vaccinated reduces the risk of a person developing symptomatic infection in the first place by up to 65 percent, four weeks after one dose. Households are deemed as "high-risk" settings for transmission.