TEL AVIV—Israel is upping the vaccine ante, pressing citizens to get Covid-19 booster shots and saying those who don't will face restrictions on traveling, dining out and other activities.

Holders of Israel's vaccine passports must get a third dose of the Pfizer -BioNTech vaccine within six months of their second dose, or lose the so-called green pass that allows them more freedom.

"We are updating what it means to be vaccinated," said Israel's coronavirus czar, Salman Zarka, at a press conference Sunday unveiling the new policy.