Weekly updates, Influenza Epidemiological Week 48 (9 December 2022)

North America: Influenza activity continues moderate in the subregion., with the predominance of influenza A(H3N2) and co-circulation of A(H1N1)pdm09 and B/Victoria. Moderate SARS-CoV-2 activity was reported and increasing, while RSV activity was moderate overall. In Canada, influenza activity and most surveillance indicators continue to increase. Mexico experiences extraordinary influenza activity for this period, with surveillance indicators at low-intensity levels. Increased influenza activity was reported across the United States, with the influenza-associated cumulative hospitalization rate at higher levels than in previous seasons (2010-21). RSV activity continued elevated but with a decreasing trend.

Caribbean: Influenza activity was low across the subregion with A(H3N2) virus predominance and A(H1N1)pdm09 co-circulation. SARS-CoV-2 activity remained low. The Dominican Republic and Puerto Rico have shown increased influenza activity, at low-intensity levels.

Central America: Influenza activity was at moderate levels, with the predominance of influenza A(H3N2) and the co-circulation of influenza B (lineage undetermined). SARS-CoV-2 activity remained low in the subregion but is increasing in Costa Rica, El Salvador, and Honduras. In addition, increased influenza activity was reported in Guatemala and Nicaragua. RSV activity continued elevated in El Salvador, Guatemala, Honduras, and Panama.

Andean: Influenza activity has recently increased 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 was elevated. In Bolivia, increased influenza activity was reported with influenza B/Victoria and A(H3N2) viruses equally detected; SARI activity increased, with 8.5% influenza-associated hospitalizations. Influenza activity was at moderate-intensity levels in Ecuador, with severity indicators at a low levels.

Brazil and Southern Cone: Influenza activity continues elevated 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. Argentina and Paraguay reported increased influenza activity with influenza B (lineage undetermined) predominance. In Chile, influenza A(H3N2) predominated, while in Uruguay was influenza B/Victoria. SARS-CoV-2 activity has increased recently, with high activity in Argentina, Brazil, and Chile. In addition, elevated RSV activity was reported in Brazil.

Global: Influenza activity increased, and where subtyped, influenza A(H3N2) viruses predominated. In Europe, overall influenza activity continued to increase, with influenza positivity from sentinel sites remaining above the epidemic threshold at the regional level. Influenza A viruses predominated among the reported detections, with A(H3N2) viruses accounting for most of subtyped influenza A viruses from sentinel sites and influenza A(H1N1)pdm09 viruses predominant among nonsentinel samples. In central Asia, influenza B virus activity continued to be reported from Kazakhstan and other countries, reporting a few influenza A and B virus detections. In Northern Africa, influenza detections were low in reporting countries. In Western Asia, influenza activity appeared to decrease overall, with all seasonal influenza subtypes detected in similar proportions. In East Asia, influenza activity of predominantly influenza A(H3N2) remained low among reporting countries, with some increases reported in southern China and the Republic of Korea. In tropical Africa, influenza activity remained low, with detections of all seasonal influenza subtypes reported. In Southern Asia, influenza activity decreased during this period mainly due to decreased activity reported in Iran (Islamic Republic of). Influenza A(H3N2) was the most frequently detected subtype in the subregion. In South-East Asia, detections of predominantly influenza A(H3N2) and influenza B continued to decrease. In the temperate zones of the southern hemisphere, influenza activity was low in most reporting countries. COVID-19 positivity from sentinel surveillance increased to over 10% after a long-term downtrend in mid-2022. Activity appeared to increase in the Region of the Americas, with percent positivity around 14%, and in the South-East Asia Region, with positivity just below 10%. In the European Region, positivity was stable, slightly below 10%. In the African, Eastern Mediterranean, and Western Pacific Regions, positivity remained below 10%. Globally, COVID-19 positivity from non-sentinel surveillance increased to around 25% in recent weeks.