A panel of vaccine experts in Canada has recommended extending the interval between the two doses of a Covid-19 shots to four months to quickly inoculate more people amid a shortage of doses in Canada. A number of provinces said they would do just that. Prime Minister Justin Trudeau also expressed optimism that vaccination timelines could be sped up. Top health officials have called it an experiment and noted no other country is doing it. The current protocol is an interval of three to four weeks between doses for the Pfizer, Moderna and AstraZeneca vaccines. Johnson & Johnson is a one dose vaccine but has not been approved in Canada yet.