LONDON (Reuters) – A single dose of Pfizer and BioNtech’s COVID-19 vaccine reduces the number of asymptomatic infections and could significantly reduce the risk of transmission of the virus, results of a UK study found on Friday.
Researchers analyzed the results of thousands of COVID-19 tests performed every week as part of hospital examinations of medical staff in Cambridge, East England.
“Our findings show a dramatic reduction in the number of positive screening tests among asymptomatic health professionals after a single dose of the Pfizer-BioNTech vaccine,” said Nick Jones, an infectious disease specialist at Cambridge University Hospital who co-led the study.
After separating the test results from unvaccinated and vaccinated personnel, Jones’s team found that 0.80% tests from unvaccinated health workers were positive.
This compares with 0.37% of staff tests less than 12 days after vaccination – when the protective effect of the vaccine has not yet been fully established – and 0.20% of staff tests 12 days or more after vaccination.
The study and its results have yet to be independently reviewed by other scientists, but were published online as preprint Friday.
This suggests a quadrupling the risk of asymptomatic COVID-19 infection in health workers vaccinated for more than 12 days, and 75% protection, said Mike Weekes, an infectious disease specialist in Cambridge University’s department of medicine, who led the study. .
The level of asymptomatic infection was also cut in half in those vaccinated for less than 12 days, he said.
Great Britain has been conducting vaccinations with both the Pfizer COVID-19 injection and one from AstraZeneca since the end of December 2020.
“This is great news – the Pfizer vaccine not only protects against SARS-CoV-2 illness, but also helps prevent infection, reducing the chance of the virus being passed on to others,” Weeks said. “But we must not forget that the vaccine does not provide complete protection for everyone.”
Key field data published Wednesday from Israel, which conducted one of the world’s fastest implementations of Pfizer’s COVID-19 vaccine, showed that two doses of the Pfizer injection reduced symptomatic COVID-19 cases by 94%. in all age groups, and serious illnesses decreased almost equally.
Reporting by Kate Kelland; Editing by David Goodman and Jane Merriman