Ontario Respiratory Virus Tool

Key findings for October 26 – November 1, 2025 (surveillance week 44)

COVID-19

• Percent positivity was low (6.0%), and overall activity was similar to the previous week.
• Highest percent positivity in those <1 years (5.5%) and 65 years and older (7.5%).
• XFG was the most prevalent lineage identified by whole genome sequencing (Oct 12-18).

Influenza

• Percent positivity was low (1.8%), and overall activity was higher than the previous week.
• Percent positivity for influenza A is highest in children (5-11 years) at 7.8% and adolescents (12-19 years) at 4.2%.
• H1N1 was more common than H3N2 this week. See Influenza Strain Details tab.
• No antiviral-resistant isolates identified in Ontario. See Influenza Strain Details tab.

RSV

• Percent positivity was low (0.6%), and overall activity was similar to the previous week.
  • Percent positivity is highest in children under 5: 6.3% (<1 year) and 5.0% (1–4 years).
    • Positivity has increased in this age group in recent weeks.