Health officials say COVID-19 cases are still trending downward nationally but warn that a hard flu season could put more pressure on the health care system. Last week, the Public Health Agency of Canada reported that the virus’s reproductive number (Rt) had fallen below one for the first time since mid-July, putting new COVID infections on a downward trajectory for the first time in months. PHAC says the past week saw an average of about 3,160 new cases per day, down 15 per cent from 3,745 average cases the previous week. WATCH: Dr. Tam provides update on COVID-19 in Canada Tam provides update on COVID-19 in CanadaDr. Theresa Tam, Canada’s chief public health officer, says we’re seeing a decline in COVID-19 disease activity nationally. 1:48 But Chief Public Health Officer Dr. Theresa Tam continues to urge precautions to avoid straining the health care system at a time when thousands of Canadians are still being treated for the virus in hospitals. Tam pointed to the approaching flu season as a reason for Canadians to remain cautious. “If a continuing fourth wave of COVID 19 were combined with a resurgence of the flu, this could place additional pressures on the health care system,” Tam told a press conference Friday. Strict health measures in place to prevent the spread of COVID-19 last fall and winter had the added effect of limiting the spread of the influenza virus, Tam said, adding last year’s flu season was virtually “non-existent.” WATCH: Dr. Tam urges Canadians to get flu shot Tam urges Canadians to get flu shotDr. Theresa Tam, Canada’s chief public health officer, says it’s especially important to get a flu shot this season since it was basically non-existent last year due to COVID-19 public health measures. 1:48 But with lighter restrictions this year and lowered population immunity due to the flu’s limited spread last year, the flu virus could be poised for a resurgence, Tam said. “Even before COVID, there are some very, very severe influenza seasons where you are already going to get the [emergency rooms] crowded and your hospitals at overcapacity. So this is definitely not the year to have influenza wreak havoc,” Tam said. Tam said preventing the spread of the flu virus will be key to protecting the health care system and encouraged Canadians to continue practicing key health measures, such as frequent hand washing, staying home when sick and getting the flu shot. “Getting the flu shot is more important now than ever,” she said. Current Pfizer stock not usable for children under 12 Pfizer and its partner BioNTech have submitted preliminary data from their trial of a COVID-19 shot for kids to Health Canada earlier than expected. A formal filing of a submission for authorization of a vaccine for children is expected in the coming days. Currently, there are no vaccines approved by Health Canada for use on children under the age of 12. Tam cautioned that once such a vaccine is approved, it won’t mean that children under 12 can line up to be vaccinated right away with the current Pfizer doses Canada currently has in stock. Children under 12 may require a lower dosage than adults. While Tam said it’s possible to draw lower doses from the vials currently in stock, she warned that it might cause the vaccine in those vials to be less effective. “You can certainly look for different kinds of needles that might do the trick, but you can’t just dilute that vial … because that might actually change some aspect of how the formulation might work,” she said.