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Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 15 (19 April 2024)

Cover Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 15 (19 April 2024)
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[WEEKLY SUMMARY]. Regional Situation: Over the past four epidemiological weeks (EWs), the Americas region has experienced moderate levels of Influenza-Like Illness (ILI) activity, with a downward trend. This trend has primarily been driven by moderate activity observed in North America and the Caribbean. Additionally, there has been a decline in Severe Acute Respiratory Infection (SARI) activity, currently at low levels. In both instances, the observed activity has been correlated with positive cases of influenza and SARSCoV- 2. Regarding the circulation of respiratory viruses, regional SARS-CoV-2 activity has decreased to low levels compared to previous epidemic waves. Similarly, there has been stable epidemic activity of influenza for this time of year, alongside a declining trend in Respiratory Syncytial Virus (RSV) activity, currently at low levels. North America: ILI cases have continued to decrease over the past four EWs, reaching intermediate levels, with the majority of cases attributed to influenza. Cases and hospitalizations associated with respiratory viruses have sustained a downward trajectory. Influenza activity has persisted at epidemic levels, albeit showing a decline over the last four EWs. During this period, the prevalent influenza strains have been type B/Victoria, alongside simultaneous circulation of influenza A(H1N1)pdm09 and influenza A(H3N2). RSV activity has decreased over the same period, remaining at low levels. SARS-CoV-2 activity has also decreased over the last four EWs, reaching low levels compared to previous waves. By country: In Canada, SARS-CoV-2 activity has notably decreased over the past four EWs, reaching low levels. Influenza activity has remained at epidemic levels, gradually declining, while RSV activity has continued to decrease, remaining at low levels. In Mexico, influenza circulation has fluctuated at epidemic levels over the last four EWs, and SARS-CoV-2 circulation has decreased to low levels. In the United States, influenza activity has decreased over the same period, though it remains above the epidemic threshold. Both RSV and SARS-CoV-2 have exhibited declining activity, reaching low levels. ILI cases have also decreased, maintaining intermediate levels. Hospitalization rates for influenza, RSV, and SARS-CoV-2 have displayed a decreasing trend over the last four EWs, reaching low levels. Caribbean: ILI and SARI cases have continued to decline over the past four weeks, with the majority of positive cases attributed to influenza and, to a lesser extent, SARS-CoV-2. Influenza activity has remained fluctuating at low levels over the same period. Predominant influenza viruses during this time have been type A(H1N1)pdm09, with concurrent circulation of influenza A(H3N2) and influenza B/Victoria to a lesser extent. RSV activity has remained low, and SARS-CoV-2 activity has also remained at low levels. By country: Over the last four EWs, influenza activity has been observed in Belize, Jamaica, and the Cayman Islands. SARS-CoV-2 activity has been observed in Barbados and Guyana. Central America: ILI and SARI activity have remained low over the past four EWs, albeit showing a gradual increase, with the majority of positive cases attributed to influenza. Influenza activity has exhibited a slight increase during this period, reaching intermediate-low levels. Predominant influenza viruses over the last four EWs have been type A(H1N1)pdm09 and A(H3N2). RSV and SARS-CoV-2 activity have both remained at low levels. By country: In El Salvador, SARI activity is around epidemic levels, with SARS-CoV-2 circulation at low levels and influenza activity fluctuating around the epidemic threshold. In Guatemala, there has been an increase in ILI and SARI cases associated with a rise in positive influenza cases, reaching epidemic activity levels. In Honduras, over the last four EWs, there has been an increase in SARI cases, reaching epidemic levels, correlated with an increase in positive influenza cases, demonstrating moderate activity levels. In Nicaragua, RSV, influenza, and SARS-CoV-2 activity are all at low levels. In Panama, influenza activity fluctuates around the epidemic threshold, and ILI and SARI cases have shown an increase over the last four EWs. Andean Region: ILI activity has remained stable at low levels, with the majority of positive cases attributed to influenza and SARS-CoV-2. SARI cases have continued to decline at low levels, with the majority of positive cases attributed to RSV. Influenza activity has remained at low levels over the last four EWs with a slight upward trend. During this period, predominant influenza viruses have been type A(H3N2), alongside concurrent circulation of A(H1N1)pdm09. RSV activity has remained low, with a slight increase. SARS-CoV-2 activity has continued on a downward trend at low levels. By country: In Colombia, SARS-CoV-2 activity has decreased over the last four EWs to low levels, while influenza and RSV activity have remained fluctuating at low levels. SARI activity has continued to decline around the epidemic threshold over the last four EWs, with positive cases attributed to RSV and influenza. In Ecuador, a significant increase in RSV activity to high levels has been observed, while SARS-CoV-2 has decreased to moderate-low levels, and influenza activity has remained below the epidemic threshold. SARI activity has fluctuated around the moderate threshold, with positive cases attributed to RSV over the last four EWs. In Peru, influenza activity has fluctuated around the epidemic threshold, and SARS-CoV-2 activity has decreased to low levels. In Venezuela, a significant increase in influenza activity above the epidemic threshold has been observed over the last four EWs. Brazil and Southern Cone: ILI and SARI activity have increased over the last four EWs, with the majority of positive cases attributed to SARS-CoV-2 and, to a lesser extent, influenza. Influenza activity has increased over the same period, reaching epidemic levels in some countries. Predominant influenza viruses during this time have been type A(H3N2) followed by A(H1N1)pdm09. RSV activity has remained at low levels. SARS-CoV-2 activity has continued to decrease, maintaining intermediate-low levels. By country: In Argentina, ILI and SARI levels have remained below the epidemic threshold. Influenza activity has shown a slight increase above the epidemic threshold, and the percentage of SARS-CoV-2 positivity has continued to decrease at low levels. In Brazil, SARS-CoV-2 activity has continued to decrease, remaining at low levels, while influenza activity fluctuates around the epidemic threshold. In Chile, both ILI and SARI cases have increased over the last four EWs, reaching epidemic levels; the majority of positive cases are attributed to SARS-CoV-2 and influenza. SARS-CoV-2 activity has decreased to low levels, and influenza activity has shown a pronounced increase above the epidemic threshold. In Paraguay, SARI activity has remained around the epidemic threshold, and ILI activity has stayed below this threshold. Influenza activity has shown a slight increase, fluctuating around the epidemic threshold; SARS-CoV-2 circulation has decreased over the last four EWs, reaching low levels, and RSV activity has remained low. In Uruguay, SARI activity has exceeded the epidemic threshold, with the majority of positive cases attributed to SARS-CoV-2, which is at moderate and decreasing levels.