Authors: Dov Lieber<\/em><\/p>\n\n\n\n TEL AVIV\u2014After becoming one of the first countries to open up thanks to a widespread Covid-19 vaccination campaign, Israel is again on guard, this time against the spread of the Delta variant<\/a> of the coronavirus.<\/p>\n\n\n\n Mask mandates are back, including requirements to mask up for large outdoor gatherings. Many venues require people to show proof of vaccination, a negative Covid-19 test or proof of recovery from the virus. People returning from most countries have to quarantine for at least a week, even if they are fully vaccinated. Over-60s are being offered a third, booster shot<\/a> of Pfizer<\/a> Inc.\u2019s vaccine, and the government is planning to offer it to younger recipients with the hopes it can suppress the rise of cases of severe illness.<\/p>\n\n\n\n Health officials are warning that Israel could face a fourth lockdown during the Jewish holiday season in September if the country doesn\u2019t improve on its 80% adult vaccination rate and deliver more booster shots.<\/p>\n\n\n\n A little over a month ago, day-to-day life in Israel was quickly getting back to normal. People were dining indoors or attending concerts without needing the so-called green pass, a digital certificate stored on phones to show the holder is fully vaccinated. But the more contagious Delta variant is forcing a change in tack, in a test case for what could happen elsewhere, including countries with high vaccination rates.<\/p>\n\n\n\n