Federal health officials are bracing Canadians for another round of COVID-19 vaccines expected to roll out in the fall, and are urging those behind on their boosters to catch up now. Canada's chief public health officer Theresa Tam says circulating Omicron subvariants BA.4 and BA.5 are more transmissible and cases are likely to rise in the coming weeks. She and Health Minister Jean-Yves Duclos are stressing the importance of up-to-date shots.