Alberta requires indoor diners to show proof of vaccination, a negative test within the last 72 hours, or a letter of medical exemption. Cities across the United States, too, are instituting new restrictions on indoor dining as the spread of the highly transmissible omicron variant has caused covid cases to surge. Starting this week, customers 12 and older must have gotten at least one dose of a coronavirus vaccine to dine inside a restaurant in Washington, D.C., and beginning Feb. 15, indoor diners must be fully vaccinated. Philadelphia, Boston, Minneapolis and St. Paul all have new vaccine requirements for indoor dining. They join cities including New York and San Francisco, which adopted such mandates last year.