Weekly updates, Influenza Epidemiological Week 9 (10 March 2023)

North America: Influenza virus activity decreased throughout the sub-region, with the predominance of influenza A(H3N2)pdm09. Influenza A(H1N1)pdm09 and B/Victoria co-circulated. SARS-CoV-2 circulates at moderate levels, and RSV activity was low. In Canada, influenza activity was low, with influenza B virus predominance. In Mexico, influenza activity decreased, while SARS-CoV-2 and RSV activity remained elevated. In the United States, influenza and RSV activity were low, while SARS-CoV-2 activity remained moderate. 

Caribbean: Influenza activity remains increased, although showing a decreasing trend, with A(H1N1)pdm09 predominance and A(H3N2) and B/Victoria co-circulation. Belize and Haiti reported increased influenza activity, with influenza A(H1N1)pdm09 predominance. Likewise, Guadeloupe, Martinique, and Saint-Martin reported increased influenza activity in the French Territories. SARS-CoV-2 activity was low in the subregion, except in Jamaica and Suriname, where it was raised. Jamaica reported increased RSV activity; elsewhere in the subregion, RSV activity was low. 

Central America: Influenza activity was moderate, with influenza B/Victoria virus predominance. Influenza A(H3N2) and A(H1N1)pdm09 co-circulated. Guatemala, Honduras, and Panama reported increased influenza activity. SARS-CoV-2 percent positivity decreased in the subregion, except in Costa Rica. RSV activity was low overall. 

Andean: Influenza activity was low, predominating influenza A(H1N1)pdm09 viruses; influenza B/Victoria and A(H3N2) viruses co‑circulated. Bolivia, Ecuador, and Venezuela reported increased influenza activity. In Bolivia, SARI cases / 100 hospitalizations were at moderate levels, and 22% tested positive for influenza. SARS‑CoV-2 and RSV activity were low overall. 

Brazil and Southern Cone: Influenza activity was at interseason levels; influenza B/Victoria viruses were detected more frequently with A(H1N1)pdm09 co-circulation. Paraguay reported increased influenza B (lineage not performed) activity at low-intensity levels. SARS-CoV-2 activity was low overall, but Brazil and Chile reported increased activity. RSV activity was low in the subregion, except in Brazil, where high levels were registered. 

Avian Influenza: A summary of the avian influenza situation in the region, case management and recommendations are available at Epidemiological alerts and updates | PAHO/WHO | Pan American Health Organization (paho.org)