A single dose of a coronavirus vaccine can reduce transmission within a household by up to half, a study by Public Health England has found.
People who do become infected with the coronavirus three weeks after receiving a single dose of the Pfizer-BioNTech or AstraZeneca-University of Oxford vaccine were between 38% and 49% less likely to pass the virus on to their household contacts than those who were unvaccinated, the PHE study found.
Protection was seen from around 14 days after vaccination, with similar levels of protection regardless of age of cases or contacts.
This protection is on top of the reduced risk of a vaccinated person developing an asymptomatic infection in the first place, which is around 60% to 65% – four weeks after one dose of either vaccine, PHE noted. Having both doses of a coronavirus vaccine (the delay between doses is up to 12 weeks in the U.K.) confers an even higher level of protection against Covid infection.
The U.K.’s Health Secretary Matt Hancock hailed the study’s findings as “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.”
“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.”
“I urge everybody to get their vaccines as soon as they are eligible and make sure you get your second dose for the strongest possible protection,” he added.