In a brief statement issued on Monday, the government said that as of June 6, the vaccine provided 64% protection against infection. In May -- when the Alpha variant dominated in Israel and the Delta strain had not yet spread widely -- it found that the shot was 95.3% effective against all infections.
The government added that the vaccine was now 93% effective in preventing severe disease and hospitalizations, compared to 97% reported in the medical journal The Lancet in May.
Separately, preliminary findings of a Scottish study published in The Lancet last month found that the Pfizer vaccine provided 79% protection against all infections from the Delta variant, compared with 92% against the Alpha variant. The same study, which analyzed data from 5.4 million people in Scotland found the the Oxford-AstraZeneca vaccine offered 60% protection against infection with the Delta variant compared with 73% for the Alpha variant.
Moderna's vaccine was found in lab experiments to work against new variants such as the Delta strain, the company said.
Johnson & Johnson said lab tests of its one-shot coronavirus vaccine suggest it provides protection against the Delta variant.