UK Study Says Single Shot of Pfizer/BioNTech Vaccine Significantly Lessened Asymptomatic Infections

A single dose of the Pfizer/BioNTech vaccine significantly lowers asymptomatic SARS-CoV-2 infections, which means it also reduces the risk of transmission from asymptomatic individuals, a new UK study has shown.

Researchers at Cambridge University analyzed thousands of COVID-19 tests from staff working in a UK hospital in January and found that healthcare workers were four times less likely to become infected with COVID-19 12 days postvaccination with a single shot — and asymptomatic infections dropped by 75 percent.

The UK analysis showed that 0.8 percent of unvaccinated healthcare workers tested positive, while only 0.2 percent of vaccinated workers were positive 12 or more days after receiving a single dose. Up to 12 days post inoculation, 0.37 percent of vaccinated workers were positive, according to the findings reported on Authorea, a pre-print website.