Single dose of Pfizer Covid-19 vaccine may protect against asymptomatic infection: Study
Feb 26, 2021
London [UK], February 26 : New research suggests a single dose of the Pfizer/BioNTech coronavirus vaccine can protect against asymptomatic coronavirus infection, which could help reduce transmission of the virus.
According to CNN, researchers used PCR tests to screen for coronavirus in vaccinated and non-vaccinated Cambridge University Hospitals health care workers who reported to work feeling well.
Unvaccinated health care workers were positive for coronavirus in 0.80 per cent of tests; vaccinated health care workers less than 12 days from a single dose were positive in 0.37 per cent of tests; vaccinated health care workers who were at least 12 days out from one dose were positive in 0.20 per cent of tests.
The study, led by Cambridge researchers, has not yet been published or peer-reviewed, but the authors call it "real-world evidence for a high level of protection against asymptomatic SARS-CoV-2 infection" from a single dose of the vaccine.
The researchers noted that the more transmissible B.1.1.7 variant, first identified in the United Kingdom, dominated at the time of their research, and prior infection was relatively low among the population tested.
A study released by Public Health England (PHE), this week, found that one dose of the Pfizer vaccine "provides high levels of protection against infection and symptomatic disease," reducing the risk of infection by 72 per cent after three weeks, while two vaccine doses reduced the risk of infection by 85 per cent. PHE's Siren Study involved health care workers younger than 65.
"These studies are very encouraging because they suggest that the vaccines will prevent the spread of the virus," Lawrence Young, a professor of molecular oncology at Warwick Medical School, said in a response to the Science Media Centre in the UK, as quoted by CNN.
"You can't spread the virus if you're not infected and these studies show that the vaccine blocks infection in individuals who don't have symptoms but could pass on the infection," Young added.
Nearly 19 million people in the UK have received at least one dose of the vaccine, in one of the world's fastest rollouts.
