The Canadian Severe Acute Respiratory Infection, Prospective, Perpetual Observational Study: Informing Clinical Care and the Public Health Response

Severe acute respiratory infection (SARI) is a major public health problem. The commonest cause of SARI is influenza which is responsible for substantial illness and death each year, in addition to outbreaks and periodic pandemics. Recent outbreaks of pandemic influenza viruses and coronaviruses such as COVID-19, have taught us not only that these viruses can lead to severe illness and death, but also that it can take a long time between the start of an outbreak and when the health care system knows enough about the illness to guide public health policy and clinical care. Each year since 2016, with a network of hospitals and infectious diseases and critical care clinicians, we have described severe respiratory infection in Canadian hospitals, the viruses and bacteria that cause people to get sick, their treatments and how often it leads to patients needing critical care or dying. When the COVID-19 pandemic hit, this team of over 50 adult and children's hospitals worked in collaboration with the World Health Organization and partners in other countries to describe severe illness from this new virus. We found that patients were typically older, more commonly men and often had pre-existing medical problems. Of patients who were sick enough to need admission to the intensive care unit, about one-quarter unfortunately still died; however, this is a much lower death rate than in many other countries hit hard by the pandemic. This ongoing study will describe whether patterns of illness change in the second and subsequent pandemic waves, and will provide a way to rapidly study common and new respiratory infections in the future to inform policy and practice.