Impact of COVID-19 pandemic on Legionella testing and infection rates in Ontario

Legionella testing rates decreased by 8% in 2020 and 8% in 2021 and increased by 14% in 2022, which was associated with a decrease in positivity rate only in 2020, at 13%, but not in the other two years. Maintaining vigilance for Legionella testing in future pandemics may support timely diagnosis and treatment, leading to improved patient outcomes. Co-detection of Legionella with SARS-CoV-2 or seasonal respiratory viruses was rare but present during the pandemic. Accordingly, Legionella testing remains essential among high-risk groups, such as the elderly with co-morbidities, critically ill patients, or those with severe or unresponsive pneumonia. Such an approach can aid in differential diagnosis, prompt appropriate treatment, and improve patient outcomes.