Weekly updates, Influenza Epidemiological Week 46 (25 November 2022)

North America: Influenza activity is moderate in the subregion, with the predominance of influenza A(H3N2) and co-circulation of influenza A(H1N1)pdm09 and influenza B (lineage undetermined). The SARS-CoV-2 activity was low but increasing, while RSV activity remained elevated overall. In Canada, influenza has risen steeply, and most surveillance indicators are increasing. In Mexico, influenza was at high-intensity levels, although surveillance indicators were at low-intensity levels. Increased influenza and RSV activity was reported across the United States, with the influenza-associated cumulative hospitalization rate at higher levels than in previous seasons (2010-21).

Caribbean: Influenza activity was moderate across the subregion with A(H3N2) virus predominance and co-circulation of influenza B (lineage undetermined). In contrast, SARS-CoV-2 activity remained low. In addition, increased influenza activity at low-intensity levels was reported in the Dominican Republic and Jamaica.

Central America: Influenza activity is increasing with the predominance of influenza A(H3N2) and the co-circulation of influenza B/Victoria. SARS-CoV-2 activity remained low in the subregion, except in El Salvador and Panama, where it increased. Increased influenza activity was reported in Guatemala and Nicaragua. Additionally, increased RSV activity was reported in El Salvador and Panama.

Andean: Influenza activity remained low, with the predominance of influenza A(H3N2) and co-circulation of influenza A(H1N1)pdm09 and B/Victoria. Overall, SARS-CoV-2 and RSV activity was low in the subregion, except in Colombia and Peru, where SARS-CoV-2 activity is increasing. In Bolivia, increased influenza activity was reported with influenza A(H1N1)pdm09 predominance and co-circulation of B/Victoria and A(H3N2) viruses; SARI activity increased, with 27% influenza-associated hospitalizations.

Brazil and Southern Cone: Influenza activity was high in the subregion for this time of year, with influenza A(H3N2) predominance and co-circulation of influenza A(H1N1)pdm09 and influenza B/Victoria. SARS-CoV-2 activity has remained low, although Argentina, Brazil, and Chile have shown an increase. Argentina and Chile reported increased influenza activity with B (lineage undetermined) and A(H3N2) predominance respectively. RSV activity remained elevated in Brazil, but with a decreasing trend.

Global: Influenza activity increased, and where subtyped, influenza A(H3N2) viruses predominated. In Europe, overall influenza activity continued increasing, with influenza positivity reported above the epidemic threshold in some countries. Influenza A viruses predominated among the reported detections, with A(H3N2) viruses accounting for most subtyped influenza A viruses. In central Asia, Kazakhstan reported high influenza activity with B/Victoria-lineage viruses predominating. In East Asia, influenza activity of predominantly influenza A(H3N2) remained stable at intermediate levels overall. In Western Asia, influenza activity remained elevated, especially in some countries of the Arabian Peninsula. In tropical Africa, influenza activity remained low, with detections of influenza A(H3N2), B/Victoria, and A(H1N1)pdm09 reported. In Southern Asia, influenza activity increased steeply mainly due to elevated activity reported in Iran (Islamic Republic of). Influenza A(H3N2) was the most frequently detected subtype in the subregion. In Southeast Asia, detections of predominantly influenza A(H3N2) and influenza B continued to decrease. In the temperate zones of the southern hemisphere, influenza activity continued to decline in most reporting countries.