A major real-world study including around 1.2 million people has found the Pfizer/BioNTech vaccine to be 94% effective following the second dose.
The research, conducted in Israel, used data from Clalit Health Services to evaluate the effectiveness of the Pfizer/BioNTech vaccine, also known as BNT162b2.
The study matched all individuals who were newly vaccinated during the period running from 20 December 2020 to 1 February 2021 to unvaccinated controls in a 1:1 ratio.
It documented outcomes including infection with severe COVID-19, symptomatic COVID-19, COVID-19-related hospitalisation, severe illness and death.
The researchers measured vaccine effectiveness for the study outcomes at days 14 to 20 after the first dose of BNT162b2, and at seven or more days after the second dose.
They found that the Pfizer/BioNTech vaccine was 57% effective at preventing symptomatic COVID-19 after the first dose, which climbed to 94% following the second dose.
After the second dose, the vaccine was also 87% effective at preventing hospitalisation and 92% effective at preventing severe disease.
The study also estimated effectiveness for the prevention of death from COVID-19 to be 72% for days 14 through 20 after the first dose.
The findings for effectiveness in preventing symptomatic COVID-19 was also consistent across all age groups, although the researchers added there could potentially be slightly lower effectiveness for people with multiple coexisting conditions.
“This study estimates a high effectiveness of the BNT162b2 vaccine for preventing symptomatic COVID-19 in a noncontrolled setting, similar to the vaccine efficacy reported in the randomised trial,” the study researchers commented in the New England Journal of Medicine.
“Our study also suggests that effectiveness is high for the more serious outcomes: hospitalisation, severe illness, and death,” they added.
Earlier this week, real-world data from the UK found that one dose of the Pfizer/BioNTech vaccine reduces the risk of infection by more than 70%, and by 95% after the second dose is administered.
The data, analysed by Public Health England (PHE), also found that in people aged 80 years and over, one dose of the vaccine is 57% effective against symptomatic COVID-19 disease.
The early findings come from the SIREN study, which involves a sample of healthcare workers who are undertaking symptom questionnaires, respiratory swabs and serum samples.
Another real-world study, conducted in Scotland by the University of Edinburgh’s Usher Institute, found that by the fourth week after receiving the first dose, the Pfizer/BioNTech and AZ/Oxford vaccines reduced the risk of hospitalisation from COVID-19 by up to 85% and 94%, respectively.