Pfizer COVID-19 vaccine reduces transmission after 1 dose, study concludes

A single dose of the COVID-19 vaccine from Pfizer and BioNtech could significantly reduce the risk of transmitting the virus, a UK study concluded.

The researchers analyzed the results of thousands of COVID-19 tests performed each week as part of the hospital team’s health screening in Cambridge, England.

Mike Weekes, an infectious disease specialist in the medical department at Cambridge University, who co-led the study, said: “This is great news – the Pfizer vaccine not only provides protection against illness from SARS-CoV-2, but it also helps to prevent infection by reducing the potential for the virus to be transmitted to other people.

“But we have to remember that the vaccine does not offer complete protection for everyone.”

The study also found that a single dose of the injection reduces the number of asymptomatic infections.

“Our findings show a dramatic reduction in the rate of positive screening tests among asymptomatic healthcare workers after a single dose of the Pfizer-BioNTech vaccine,” said Nick Jones, an infectious disease specialist at Cambridge University Hospital, another co-leader of the study.

After separating the test results from unvaccinated and vaccinated employees, Jones’s team found that 0.80% of tests by unvaccinated healthcare workers were positive.

This compares to 0.37% of the team’s tests less than 12 days after vaccination – when the protective effect of the vaccine is not yet fully established – and 0.20% of the team’s tests 12 days or more after vaccination.

The study and its results have yet to be reviewed by independent peers by other scientists, but were published online on Friday.

This suggests a four-fold reduction in the risk of asymptomatic COVID-19 infection among healthcare professionals who have been vaccinated for more than 12 days and 75% protection, said Weekes.

The level of asymptomatic infection has also been halved in people vaccinated for less than 12 days, he said.

Britain has been launching vaccines with the Pfizer COVID-19 vaccine and one from AstraZeneca since the end of December 2020. The United States is using the Pfizer-BioNTech vaccine and a vaccine from Moderna Inc. in its vaccination program.

Important real-world data published on Wednesday in Israel, which carried out one of the world’s fastest launches of Pfizer’s COVID-19 vaccine, showed that two doses of Pfizer injection reduced symptomatic COVID-19 cases by 94% in all age groups, and almost as much serious illness.