Group A Streptococcal Infections in Alberta, Canada 2018-2023

Group A streptococcal or infections have been increasing post-COVID-19 pandemic. We describe the epidemiology of pharyngitis and invasive disease in Alberta, Canada 2018-2023. Positive pharyngitis specimens were identified from throat swabs collected from pharyngitis patients. Invasive was defined as the isolation of from a normally sterile site or severe skin infection. isolates were typed. Pharyngitis and invasive disease displayed seasonal trends preceding the COVID-19 pandemic followed by a sharp decrease during COVID-19 intervention measures. After the lifting of interventions, rates of pharyngitis and invasive disease rose. There were 182 983 positive pharyngitis specimens between 2018 and 2023 for a positivity rate of 17.6%. The highest rates occurred in the 0-9 age group in 2023 (41.5%). Invasive disease increased in 2022-2023 driven by 1 and 12 types. M1 strain was the most frequent M1 type associated with invasive disease (59% of M1 isolates sequenced). Notably, out of 182 983 pharyngitis cases, there were 111 cases of invasive detected for an invasive disease rate of 0.06%. This descriptive epidemiology of pharyngitis and invasive disease highlights the rapid increase in cases of occurring in western Canada and illustrates the critical need for a vaccine.