JERUSALEM (BLOOMBERG) - Israel has recorded a steep drop in the efficacy rate of the Pfizer-BioNTech vaccine in preventing coronavirus infections, due to the spread of the Delta variant and the easing of government restrictions, Ynet news website reported, citing Health Ministry data.

At the same time, the decline in protection against serious cases and hospitalisation is considerably milder, the website said. There was no immediate comment from the ministry.

The figures show that between May 2 and June 5, the vaccine had a 94.3 per cent efficacy rate. From June 6, five days after the government cancelled coronavirus restrictions, until early July, the rate plunged to 64 per cent.

A similar decline was recorded in protection against coronavirus symptoms, the report said.

At the same time, protection against hospitalisation and serious illness remained strong. From May 2 to June 5, the efficacy rate in preventing hospitalisation was 98.2 per cent, compared with 93 per cent from June 6 to July 3.

A similar decline in the rate was recorded for the vaccine's efficiency in preventing serious illness among people who had been inoculated.

These figures are in line with ministry data that show many of the new cases are among people who have been vaccinated, while the number of serious cases is rising much more slowly, Ynet said.

Last Friday, 55 per cent of the newly infected had been vaccinated, the website said. As at July 4, there were 35 serious cases of coronavirus in Israel, compared with 21 on June 19.

The government is considering reinstating additional coronavirus-related restrictions after restoring a mandate to wear masks indoors in public spaces.

Officials are also discussing whether to recommend a third dose of vaccines, the report said.

Pfizer chief executive Albert Bourla has said people will "likely" need a third dose of a Covid-19 vaccine within 12 months of getting fully vaccinated.

Israel had one of the world's most effective coronavirus inoculation drives.

Some 57 per cent of the general population is fully vaccinated, including 88 per cent of the population above the age of 50 - the group considered most at risk for serious cases.