JERUSALEM - The effectiveness of the Pfizer vaccine against COVID-19 has dropped to 39 percent in Israel, the country's Ministry of Health said on Thursday.

The new figure refers to the period between June 20 and July 17, the ministry said, adding that the ongoing decline was observed along with the spread of the Delta COVID-19 variant in Israel.

The latest effectiveness rate is significantly lower than that of 64 percent measured between June 6 and July 3, and 94.3 percent measured between May 2 and June 5.

However, the effectiveness of the vaccine in preventing severe coronavirus disease in Israel is currently estimated at 91.4 percent, and in preventing COVID-19 hospitalization, at 88 percent.

Since the start of the vaccination campaign in Israel on Dec. 20, 2020, over 5.75 million people in Israel, or 61.6 percent of the population, have received the first dose of the vaccine, while 5.28 million have received the second dose.