Pfizer Inc. and BioNTech SE’s COVID-19 vaccine was overwhelmingly effective against the virus in a study that followed nearly 1.2 million people in Israel, results that public-health experts said show that immunizations could end the pandemic.

Two doses of the vaccine prevented 94% of COVID-19 cases in 596,618 people vaccinated between Dec. 20 and Feb. 1, about one-quarter of whom were over the age of 60, teams from the Clalit Research Institute and Harvard University reported in a study published Wednesday in the New England Journal of Medicine.

The researchers matched each vaccinated person with someone who hadn’t gotten a shot, enabling the best analysis yet of whether extremely good results from an earlier clinical trial would hold up in the real world. The Pfizer-BioNTech shot cleared every hurdle. It was so effective, in fact, that outside experts said that with broad enough use it may be possible to halt the pandemic.