Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 32 (18 August 2023)

Abstract

[WEEKLY SUMMARY]. North America: Influenza activity has remained at low levels. Over the past 4 epidemiological weeks (EW), the predominant influenza viruses have been influenza A(H1N1)pdm09, with concurrent circulation of influenza B/Victoria. Respiratory syncytial virus (RSV) activity has stayed at low levels. The activity of SARS-CoV-2 has shown an increase over the last 4 EWs and continues to circulate at moderate levels. Cases of influenza-like illness (ILI) and severe acute respiratory infection (SARI) have seen a slight increase, with the majority of these cases associated with SARS-CoV-2 and to a lesser extent with influenza. In Mexico, epidemic levels of influenza circulation have been detected, which are decreasing. Caribbean: Influenza activity continues to show a decreasing trend over the past 4 EWs, with a predominance of influenza B/Victoria and, to a lesser extent, circulation of influenza A, mainly A(H1N1)pdm09. RSV activity has remained low. The activity of SARS-CoV-2 has shown an increasing trend over the last three EWs, with intermediate levels of circulation, especially in Barbados, Grenada, Guyana, Jamaica, and Saint Lucia. ILI and SARI cases have displayed a decreasing trend in the past 4 EWs. Central America: After reaching a peak in previous weeks, influenza activity has continued to decline over the last 4 EWs. During this period, the predominant influenza viruses have been influenza B/Victoria with concurrent circulation of influenza A, mainly A(H1N1)pdm09, and to a lesser extent, influenza A(H3N2). RSV activity has increased in the last 4 EWs, reaching intermediate to high levels of circulation. The activity of SARS-CoV-2 has remained low. ILI activity has remained low, with the majority of cases associated with influenza. SARI activity is currently declining, with the majority of cases associated with RSV. In Costa Rica, extraordinary levels of influenza positivity are detected with concurrent circulation of SARS-CoV-2. ILI and SARI levels remain low, with the majority of cases associated with influenza and, to a lesser extent, with SARS-CoV-2. In El Salvador, influenza activity is decreasing, with epidemic levels in reported SARI cases. Additionally, there has been an increase in RSV positivity levels with elevated activity. In Honduras, after reaching elevated levels in the percentages of influenza positivity, the last 4 EWs have seen a decline to levels below the epidemic threshold. ILI and SARI cases are currently decreasing, with almost all positive cases related to influenza. In Guatemala, RSV activity continues to rise with moderate to high levels, and ILI cases are mostly positive for influenza, while SARI cases are positive for RSV. In Nicaragua and Panama, after achieving moderate activity levels in previous EWs, influenza positivity in both countries is currently at epidemic levels. Andean region: Influenza activity remains stable at low levels. Over the last 4 EWs, the predominant influenza viruses have been influenza A, predominantly A(H1N1)pdm09, with lesser circulation of influenza B/Victoria. RSV activity remains at low levels. SARSCoV- 2 has shown a decline over the last 4 EWs, circulating at low levels, although circulation remains elevated in Bolivia. SARI activity continues to decline, with most cases associated with influenza and, to a lesser extent, RSV and SARS-CoV-2. ILI activity has shown a decreasing trend, with most cases associated with influenza.. Brazil and Southern Cone: Influenza activity has decreased to low levels of circulation. Over the past 4 EWs, the predominant viruses have been primarily influenza A(H1N1)pdm09, with simultaneous circulation of influenza B/Victoria. RSV activity has declined in the last 4 EWs, reaching low levels of circulation. SARS-CoV-2 activity has remained low, albeit with a slight increase. Both SARI and ILI activities have continued to decline over the past 4 EWs. Argentina continues to experience epidemic levels of influenza activity, with the majority of detected cases being positive for influenza A(H1N1)pdm09 and ILI and SARI levels below the epidemic threshold. In Brazil, influenza and RSV activity remains low, while SARS-CoV-2 has shown a slight increase in the last EW. In Chile, ILI activity has increased, remaining at moderate levels, with the majority of positive cases related to influenza. In Paraguay, SARI activity remains high, with RSV being the primary cause among positive cases, followed by SARS-CoV-2. In Uruguay, SARI activity remains at epidemic levels, with the majority of cases associated with RSV.

[RESUMEN SEMANAL]. Norteamérica: La actividad de influenza ha permanecido en niveles bajos. Durante las últimas 4 semanas epidemiológicas (SE) los virus influenza predominantes han sido influenza A(H1N1)pdm09, con circulación concurrente de influenza B/Victoria. La actividad del virus sincitial respiratorio (VSR) se ha mantenido en niveles bajos. La actividad del SARS-CoV-2 ha presentado un incremento en las últimas 4 SE y continúa circulando en niveles moderados. Los casos de enfermedad tipo influenza (ETI) e infección respiratoria aguda grave (IRAG) han presentado un ligero incremento, siendo la mayor parte de estos asociados a SARS-CoV-2 y en menor medida a influenza. En México se han detectado niveles epidémicos de circulación de influenza que continúa en descenso. Caribe: La actividad de la influenza continúa mostrando una tendencia decreciente en las últimas 4 SE, con predominio de influenza B/Victoria, y en menor medida circulación de influenza A, principalmente A(H1N1)pdm09. La actividad del VSR ha permanecido baja. La actividad del SARS-CoV-2 ha mostrado una tendencia creciente en las últimas tres SE con niveles intermedios de circulación, especialmente en Barbados, Grenada, Guyana, Jamaica y Saint Lucia. Los casos de ETI e IRAG han mostrado una tendencia decreciente en las últimas 4 SE. Centroamérica: Tras alcanzar un pico en semanas previas, la actividad de influenza ha continuado en descenso durante las 4 últimas SE. Durante este periodo, los virus predominantes han sido influenza B/Victoria con circulación concurrente de influenza A, principalmente A(H1N1)pdm09, y en menor medida de influenza A(H3N2). La actividad del VSR ha aumentado en las últimas 4 SE, situándose en niveles intermedios-altos de circulación. La actividad de SARS-CoV-2 se ha mantenido baja. La actividad de ETI se ha mantenido baja con la mayoría de los casos asociados a influenza. La actividad de IRAG se encuentra actualmente en descenso, con la mayoría de los casos asociados al VSR. En Costa Rica se mantienen niveles de positividad de influenza extraordinarios, coincidentes con la circulación de SARS-CoV-2. Los niveles de ETI e IRAG continúan siendo bajos con la mayoría de los casos asociados a influenza y en menor medida a SARS-CoV-2. En El Salvador la actividad de influenza se mantiene en descenso, con niveles epidémicos en los casos IRAG notificados. Adicionalmente, se ha observado un incremento en los niveles de positividad de VSR con una actividad elevada. En Honduras tras alcanzar niveles elevados en los porcentajes de positividad de influenza, en las 4 últimas SE se ha observado un descenso hasta niveles por debajo del umbral epidémico. Los casos de ETI e IRAG actualmente se encuentran en descenso siendo casi la totalidad de los positivos relacionados con influenza. En Guatemala la actividad del VSR continúa en ascenso con niveles moderados-altos, y los casos ETI positivos en su mayoría son debidos a influenza y los casos IRAG positivos para VSR. En Nicaragua y Panamá tras los niveles de actividad moderados