Single Shot of Pfizer/BioNTech Vaccine Reduced Asymptomatic Infections, UK Study Finds

A single dose of the Pfizer/BioNTech vaccine significantly lowers asymtopmatic SARS-CoV-2 infections, which means it also reduces the risk of transmission from asymtopmatic 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 postinoculation, 0.37 percent of vaccinated workers were positive, according to the findings reported on Authorea, a pre-print website.

The rate of asymptomatic infection was also discovered to be cut in half within 12 days of vaccination with a single dose, the researchers said.

In addition, the Cambridge team evaluated the symptomatic hospital staff, finding that 1.71 percent of unvaccinated workers tested positive for COVID-19 infection vs. 0.4 percent of healthcare workers 12 or more days following a single shot.

“This is great news — the Pfizer vaccine not only provides protection against becoming ill from SARS-CoV-2 but also helps prevent infection, reducing the potential for the virus to be passed on to others,” said Mike Weekes, the study’s lead researcher.

Click to read the study: bit.ly/3aXiop3. ― Jason Scott