India will begin vaccinating teenagers from the ages of 15 to 18 from Jan. 3 and also administer booster vaccine doses for health-care workers a week later, as omicron-fueled Covid-19 cases spike, Prime Minister Narendra Modi said.

France and Greece have both announced plans to mandate coronavirus vaccinations for health-care workers as the more virulent delta variant gains ground across Europe, threatening even those nations with high or climbing inoculation rates.