Weekly update, Influenza. Epidemiological week 33 (August 31, 2022)

North America: Overall, influenza activity declined in the subregion, and influenza A(H3N2) predominated. SARS-CoV-2 activity continued elevated overall. In Mexico, influenza activity increased, and SARS-CoV-2 positivity continued elevated but decreasing. In the United States, influenza activity was low, while SARS-CoV-2 activity remained high, although decreasing. 

Caribbean: Overall, influenza activity remained low, with the predominance of influenza A(H3N2). In Belize, influenza activity was at moderate-intensity levels, with influenza A(H3N2) circulating. The Domican Republic, Haiti, and Saint Lucia reported increased SARS-CoV-2 activity, with increased SARI activity in Haiti, with levels above average for this time of year.

Central America: Overall, influenza activity decreased, with the predominance of influenza A(H3N2). In Panama, influenza activity decreased to low-intensity levels, while RSV remained elevated in Nicaragua. SARS-CoV-2 activity decreased across the subregion.

Andean Countries: Influenza activity remained low, with A(H3N2) predominance. SARS-CoV-2 activity continued to be elevated in Bolivia, Ecuador, and Peru, with increased SARI activity driven by SARS-CoV-2 infections.

Brazil and Southern Cone: Overall, influenza activity remained low with influenza A(H3N2) predominance. In Chile, influenza activity continued elevated. SARS-CoV-2 activity has decreased throughout the subregion, except in Argentina. In Uruguay, SARI activity was elevated above epidemic levels for the period. ILI activity continued to increase in Chile at moderate- intensity levels driven by influenza and SARS-CoV-2.

Global: Influenza activity has steadily decreased from a peak in March 2022, except in Southeast Asia, where influenza activity increased. In the temperate zones of the southern hemisphere, overall influenza activity appeared to decrease during this reporting period. In Oceania, detections of primarily influenza A(H3N2) decreased overall, and influenza-like illness (ILI) activity returned to low levels in most Pacific Island countries. In Southern Africa, influenza activity decreased in general with continued detections of influenza A(H1N1)pdm09, influenza A(H3N2), and a few influenza B viruses. In tropical Africa, influenza activity decreased with influenza A(H3N2) viruses predominant among the reported detections. In Southern Asia, influenza detections of predominantly A(H3N2) viruses decreased while detections of influenza A(H1N1)pdm09 increased in recent weeks, especially in India. In South-East Asia, influenza activity increased overall with predominantly detected influenza A(H3N2) viruses. In Europe, influenza activity remained at inter-seasonal levels, with influenza A(H3N2) predominant among the subtyped viruses. In Central Asia and Northern Africa, no influenza detections were reported. In East Asia, influenza activity of predominantly influenza A(H3N2) seemed to have peaked in the southern provinces of China. Elsewhere, influenza illness indicators and activity remained low. In Western Asia, low numbers of detections of influenza A(H1N1)pdm09, A(H3N2), and B viruses were reported.

COVID-19 positivity from sentinel surveillance continued to decrease and was at approximately 40% in the reporting period. The highest positivity rate was reported in the Americas, while the other regions remained below 20%. Activity from non- sentinel sites remained stable, with overall positivity around 40%.