COVID-19 pandemic has brought about a whole new lexicon of words and phrases over the past 18 months, and Prime Minister Justin Trudeau introduced another one last week: “one-dose summer, two-dose fall.”He made the reference in a press conference when asked about when Canadians could see some of the restrictions in place to limit the spread of the coronavirus lift, and what the current rollout plan means for the hopes of a close-to-normal summer.Following his response, he faced more questions about what exactly a “one-dose summer” means and experts say the situation highlights the difficulties politicians face in trying to communicate around a core — yet challenging — tenet of science: it can always change.“It’s a very catchy phrase to have.