People may be able to hug their loved ones again after June 21, a government scientific adviser has said, following research that suggests one dose of the Covid-19 vaccine reduces household transmission by up to half.
The Public Health England (PHE) study suggests those who do become infected three weeks after receiving their first dose of the Pfizer-BioNTech or AstraZeneca vaccine were between 38% and 49% less likely to pass the virus on to their household contacts than those who were unvaccinated.
Dr Mike Tildesley, from the University of Warwick and a member of the Scientific Pandemic Influenza Group on Modelling (Spi-M) group, said vaccines were doing the job of preventing most people falling seriously ill, and he was hopeful hugs would be back on the agenda by the date the government has set for lifting legal limits on social contact.
“I think the key thing is that if you’re both vaccinated, of course, it does reduce the risk of anyone becoming severely ill,” he said, commenting on the PHE study, “and my hope is that as we move towards that June date, we will be in a position that we can not just see our loved ones, but also we can hug our loved ones because it’s been a very long time since we’ve been able to do that.”
While we know Covid-19 vaccines can reduce the chance of serious illness, it’s been less clear until now whether the vaccines help reduce transmission, or if vaccinated people can still spread the virus.
Households are high-risk settings for transmission and provide early evidence on the impact of vaccines in preventing onward transmission, researchers said. Similar results could be expected in other settings with similar transmission risks, such as shared accommodations and prisons.
By linking case and household contact data with vaccination status, the study compared the likelihood of transmission for a vaccinated case with an unvaccinated one.
The study included over 57,000 contacts from 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.
Protection was seen from around 14 days after vaccination, with similar levels of protection regardless of age of cases or contacts. This is 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 Immunisation at PHE, urged people still to show caution, despite the study results.
“While these findings are very encouraging, even if you have been vaccinated,” she said. “It is really important that you continue to act like you have the virus, practise good hand hygiene and follow social distancing guidance.”