Regional Update, Influenza. Epidemiological Week 49 (16 December 2022)

ABSTRACT

[WEEKLY SUMMARY]. North America Influenza activity was moderate in the subregion. Influenza A(H3N2) predominated, with the co-circulation of A(H1N1)pdm09 and B/Victoria. The SARS-CoV-2 activity was moderate and continued to increase, while RSV activity was moderate but decreasing. In Canada, influenza activity was elevated, and most surveillance indicators were above expected levels. In Mexico, influenza activity continued above expected levels for this period, with surveillance indicators at low-intensity levels. Increased influenza activity was reported across the United States, with influenza-associated cumulative hospitalization rates higher than the highest cumulative in-season hospitalization rate observed in week 49 (2010-21). Elevated RSV activity continued but with a decreasing trend. Caribbean Influenza activity was moderate across the subregion with A(H3N2) virus predominance and A(H1N1)pdm09 co-circulation. SARS-CoV-2 activity remained low overall. Haiti and Puerto Rico have shown increased influenza activity, at low-intensity levels. Jamaica reported increased activity levels. Central America Influenza activity was at moderate levels, with the predominance of influenza A(H3N2) and the co-circulation of influenza B/Vitoria (where lineage was determined). Increased influenza activity was reported in Honduras and Guatemala. SARS-CoV-2 percent positivity increased in the subregion overall, while elevated RSV activity continued in El Salvador, Guatemala, Honduras, and Panama. Andean Influenza activity was low, with the predominance of influenza A(H3N2) and co-circulation of influenza A(H1N1)pdm09 and B/Victoria. Bolivia and Ecuador reported increased influenza B/Victoria and A(H3N2) detections, with increased SARI activity at moderate levels in Bolivia and low levels in Ecuador. In addition, SARS-CoV-2 percent positivity increased in Colombia, Ecuador, and Peru. In the subregion, RSV activity was low overall. Brazil and Southern Cone Influenza activity continues elevated but with a decreasing trend, with influenza A(H3N2) predominance and co-circulation of influenza A(H1N1)pdm09 and influenza B/Victoria. Argentina reported increased influenza activity with influenza B (lineage undetermined) predominance. In Chile, influenza A(H3N2) predominated, while influenza B/Victoria was in Uruguay. The SARS-CoV-2 activity was elevated across the subregion. Elevated RSV activity continued to be reported in Brazil.