According to a new study by Public Health England (PHE), a single dose of a Covid-19 vaccine can cut transmission by up to half.
The groundbreaking results raise further hope that the pandemic can be brought under control, as vaccinated people are far less likely to spread the virus to others.
The new study found that people who were given a single dose of the Pfizer / BioNTech or Oxford / AstraZeneca vaccines and who became infected at least three weeks later were 38% to 49% less likely to pass the virus on to people who did it live their homes compared to those who were not vaccinated.
Protection was observed approximately 14 days after vaccination with similar values regardless of a person’s age.
Other studies have already shown that both vaccines are highly effective in preventing people from getting sick and ending up in the hospital.
Experts will now assess whether two doses of the vaccine can reduce the transmission of the virus even further.
Further work on transmission in the population is in progress.
PHE said similar results could be expected in places where the risk of transmission is similar to that at home, such as in shared apartments and prisons.
The study included data from January and February when the Kent tribe dominated the UK.
Health and Welfare Secretary Matt Hancock said, “This is great news – we already know vaccines save lives and this study is the most comprehensive real-world data to show that it can also stop the transmission of this deadly virus.”
“It further underscores that vaccines are the best way out of this pandemic as they protect you and potentially prevent you from unwittingly infecting anyone in your household.
“I urge everyone to get their vaccines as soon as they are eligible and make sure you get your second dose to ensure the best possible protection.
“This is a tremendous national effort and we will fight the virus together.”
What the study found – and who participated
The study, which has not yet been peer-reviewed, included over 57,000 people in 24,000 households who were the contacts of a vaccinated person.
They have been compared to nearly a million contacts made by people who did not have a vaccine.
Contacts were defined as secondary cases of coronavirus when they tested positive two to 14 days after the first household case.
Most of the people in the study were under 60 years of age.
Covid vaccines “are critical to returning to a normal way of life”
Dr. Mary Ramsay, PHE’s director of vaccinations, said, “Vaccines are critical to getting back to a normal way of life.
“Vaccines not only reduce the severity of the disease and prevent hundreds of deaths every day. We are now also seeing that they have an additional impact in reducing the likelihood of passing Covid-19 on to others.
“I encourage anyone who is offered a vaccine to take it as soon as possible.
“While these results are very encouraging, even if you have been vaccinated, it is really important that you continue to act like you have the virus, practice good hand hygiene, and follow social distancing instructions.”
Dr. Peter English, a retired communicable disease control consultant, said the study was robust and the authors may actually have underestimated the effect vaccines had on transmission.
He added, “These findings are really important. They add to our reasons to hope that the vaccines really boost herd immunity.
“There was already growing evidence that vaccination will prevent people from becoming infected (and if they are not infected, they cannot transmit the infection).
“This study shows that even if vaccinated people become infected, the likelihood that they will be infectious and pass the infection on to others is significantly lower.
“This is an extremely encouraging set of findings.”
Pfizer and AstraZeneca vaccines are credited with saving 10,400 lives among those over 60 in late March.
Data from the University of Oxford’s national Covid-19 infection survey and the Office for National Statistics (ONS) last week also showed that vaccines are likely to reduce transmission.
Just one dose of the Pfizer BioNTech or AstraZeneca vaccines reduced coronavirus cases by two-thirds and, according to the UK, was 74% effective against symptomatic infections in practice.
After two doses of Pfizer, there was a 70% decrease in all cases and a 90% decrease in symptomatic cases – these are the people most likely to spread the coronavirus to others.