LONDON (Reuters) – A single dose of COVID-19 vaccine Pfizer and BioNtech reduces the number of asymptomatic infections and could significantly reduce the risk of transmitting the virus, according to a UK study found on Friday.
The researchers analyzed the results of thousands of COVID-19 tests performed each week as part of screenings at a medical staff hospital in Cambridge, eastern England.
“Our findings show a dramatic reduction in the rate of positive screening among asymptomatic health care workers after a single dose of Pfizer-BioNTech vaccine,” said Nick Jones, an infectious disease specialist at Cambridge University Hospital who led the study.
After separating the test results from unvaccinated and vaccinated staff, Jones’ team found that 0.80% of unvaccinated health workers tested positive.
This was compared with 0.37% of tests performed by staff less than 12 days after vaccination – when the protective effect of the vaccine is not yet fully established – and 0.20% of tests performed by staff at 12 days or more after vaccination.
The study and its results have not yet been independently evaluated by other scientists, but were published online as a prepress on Friday.
This suggests a fourfold reduction in the risk of asymptomatic COVID-19 infection among health care workers who have been vaccinated for more than 12 days and 75% protection, said Mike Weekes, an infectious disease specialist at the medical department. of the University of Cambridge, who conducted the study.
The level of asymptomatic infection was also halved in those vaccinated in less than 12 days, he said.
The UK is launching vaccinations with both the Pfizer COVID-19 shot and one from AstraZeneca from the end of December 2020.
That’s great news – the Pfizer vaccine not only provides protection against SARS-CoV-2 disease, but also helps prevent infection, reducing the potential for the virus to be passed on to others, Weeks said. “But we must remember that the vaccine does not provide complete protection for everyone.”
Key real-world data released Wednesday by Israel, which carried out one of the fastest Pfizer COVID-19 vaccine launches, showed that two doses of Pfizer vaccine reduced symptomatic COVID-19 cases by 94% in all age groups. and serious diseases almost as much.
Reporting by Kate Kelland; Edited by David Goodman and Jane Merriman