AFP – The Pfizer Covid-19 vaccine has proven 94% effective in a study involving 1.2 million people in Israel, the first peer-reviewed real world research confirming the power of mass immunization campaigns to bring the pandemic to a close.
The paper, which was published in the New England Journal of Medicine on Wednesday, also demonstrated there is likely a strong protective benefit against infection, a crucial element in breaking onward transmission.
The fact that the vaccines worked so well in the real world... really does suggest that if the nations of the world can find the will, we now have the means to end Covid-19 forever, said Ben Neuman, a virologist from Texas A&M University who was not involved in the research.
The experiment was carried out between Dec 20 2020 and Feb 1, 2021 - a period when a newer variant first identified in Britain was rampant in Israel, making the vaccine's performance all the more impressive.
Around 1.2 million people were divided into equal groups of vaccinated and unvaccinated. Each vaccinated participant was matched to an unvaccinated control person of similar age, sex, geographic, medical and other characteristics.
Lead author Noam Barda, head of epidemiology and research at the Clalit Research Institute, said the matching process was highly robust.
The efficacy against symptomatic infections was 57% between 14-20 days after the first dose, but rose to 94% seven days after the second dose - very close to the 95% achieved during Phase 3 clinical trials.
People who received second doses were also highly protected against hospitalization and death - though the precise numbers here are less significant and had a wider statistical range because of the relatively lower number of cases. The study also found people who received their second dose had a 92% lower chance of getting any form of infection at all compared to those who were unvaccinated.