A single dose of a coronavirus vaccine can reduce household transmission of the virus by up to half, a study shows.
Those given a first dose of either the Pfizer or AstraZeneca vaccines – and who became infected three weeks later – were between 38% and 49% less likely to pass the virus on than unvaccinated people, PHE found.
Health Secretary Matt Hancock described the study’s results as “terrific news”.
He has urged “everybody to get their vaccines as soon as they are eligible”.
In the study, protection against Covid was seen from about 14 days after vaccination, with similar levels of protection regardless of age of cases or contacts, PHE said in a statement.
It added that this protection was on top of the reduced risk of a vaccinated person developing symptomatic infection in the first place, which is around 60 to 65% – four weeks after one dose of either vaccine.
Dr Mary Ramsay, head of immunization at PHE, said: “Vaccines are vital in helping us return to a normal way of life. Not only do vaccines reduce the severity of illness and prevent hundreds of deaths every day, we now see they also have an additional impact on reducing the chance of passing Covid-19 on to others.”
But, while she said the findings were “encouraging”, she said it was important people continue to act like they have the virus, “practise good hand hygiene and follow social distancing guidance”.
Households are high-risk settings for transmission, meaning the study provides early evidence on the impact of vaccines in preventing onward transmission, PHE said.
Similar results could be expected in other settings with similar transmission risks, such as shared accommodation and prisons, it added.