OTTAWA — Health Canada has approved Paxlovid, Pfizer’s oral antiviral treatment for COVID-19 that has been touted as a way to ease pressure on health-care systems overburdened by rising case counts. According to an authorization posted on the regulator’s web page Monday morning, the treatment has been approved for adults with mild to moderate forms of the illness who are at high risk of developing more severe outcomes. Because safety and efficacy data was not submitted to Health Canada on the use of the drug on younger age groups, Paxlovid has not been approved for pediatric patients. The pill is...