The Delta coronavirus variant can transmit easily from vaccinated people to their household contacts, a British study found on Thursday, although contacts were less likely to get infected if they were vaccinated themselves.
The Imperial College London study illustrates how the highly transmissible Delta variant can spread even in a vaccinated population.
The researchers underlined that did not weaken the argument for vaccination as the best way of reducing serious illness from COVID-19 and said booster shots were required.
They found infections in the vaccinated cleared more quickly, but the peak viral load remained similar to the unvaccinated.
“By carrying out repeated and frequent sampling from contacts of COVID-19 cases, we found that vaccinated people can contract and pass on infection within households, including to vaccinated household members,” Dr Anika Singanayagam, co-lead author of the study, said.
“Our findings provide important insights into… why the Delta variant is continuing to cause high COVID-19 case numbers around the world, even in countries with high vaccination rates.”