A single shot of Pfizer and BioNTech’s COVID-19 vaccine reduces the risk of infection by 70%, the first real-world UK data suggests

A single shot of Pfizer and BioNTech’s COVID-19 vaccine reduces the risk of infection by 70%, the first real-world UK data suggests

Pfizer and BioNTech's two-dose COVID-19 vaccine provides strong protection against infection with just one shot, and probably stops people spreading the virus, according to the results of a large-scale, real-world study published Monday. 

"One dose reduces the risk of catching infection by more than 70%, rising to 85% after the second dose," Public Health England (PHE)said in a press release Monday. "This suggests the vaccine may also help to interrupt virus transmission, as you cannot spread the virus if you do not have infection."

The study authorssaid that "significant protection from infection" kicked in from 10 days after the shot, and plateaued after 21 days. 

The findings show that Pfizer's vaccine works against the coronavirus variant in the UK, called B.1.1.7, which was highly prevalent in the UK during the study period, the authors said.

B.1.1.7 is estimated to be 30-50% more contagious, and has spread worldwide, including to 44 states in the US, according tothe Centers for Disease Control and Prevention (CDC). 

More than 32.8 million doses of Pfizer's shot has been rolled out in the US so far, according to the CDC .

PHE's ongoing SIRENstudy has followed more than 23,000 UK health care workers for two months, testing them each week for COVID-19