Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 21 (31 May 2024)

[WEEKLY SUMMARY]. been observed across the Americas. At the same time, moderate levels of Severe Acute Respiratory Infection (SARI) activity have been noted, particularly related to activity in Brazil and the Southern Cone. Both cases have been associated with positive influenza and RSV cases. Regarding the circulation of respiratory viruses, SARS-CoV-2 activity has declined to low levels regionally compared to previous epidemic waves. Additionally, there has been epidemic-level influenza activity for this time of year, and low levels of Respiratory Syncytial Virus (RSV) activity. North America: ILI cases and hospitalizations associated with respiratory viruses have continued to decline over the past four EWs, remaining at low levels. Influenza activity has also continued to decrease, staying below the epidemic threshold. During this period, the predominant influenza viruses have been type B/Victoria, with lesser circulation of influenza A(H3N2) and A(H1N1)pdm09. RSV activity has shown a decline over the last four EWs, remaining at low levels. SARS-CoV-2 activity has remained low, with a slight increase. By country: In Canada, SARS-CoV-2 activity has remained low, with a slight increase. Influenza activity has dropped below the epidemic threshold, and RSV activity has remained low. In Mexico, influenza circulation has fallen below the epidemic threshold. In the United States, ILI cases have decreased and remain low. Hospitalization rates for influenza, RSV, and SARSCoV- 2 have shown a decreasing trend over the past four EWs, remaining at low levels. Influenza, RSV, and SARS-CoV-2 activities are all at low levels. Caribbean: ILI and SARI cases have been declining over the past four weeks, with most positive cases attributable to influenza and SARS-CoV-2. Influenza activity has fluctuated at low levels during the last four EWs. During this period, the predominant viruses have been type A(H3N2), with concurrent circulation of influenza A(H1N1)pdm09 and, to a lesser extent, B/Victoria. RSV activity has remained low. SARS-CoV-2 activity has shown a marked increase in the last two weeks, reaching elevated levels. By country: Influenza activity has been observed over the last four EWs in Guyana and the Cayman Islands. SARS-CoV-2 activity has been noted in Barbados, Guyana, and the Cayman Islands. Central America: Both ILI and SARI activity has increased over the last four EWs, with most positive cases attributable to influenza. Influenza activity has seen a rise during this period, reaching intermediate levels. In the last four EWs, the predominant influenza viruses have been type A(H3N2), with concurrent circulation of A(H1N1)pdm09. RSV and SARS-CoV-2 activity has remained at low levels. By country: In El Salvador, influenza circulation has risen to moderate activity levels. In Guatemala, during the last four EWs, ILI and SARI activities have fluctuated around the epidemic threshold, with most positive cases attributable to influenza, which is declining at epidemic levels. In Honduras, fluctuating SARI activity at epidemic levels has been noted over the past four EWs, associated with positive influenza cases at moderate levels. In Nicaragua, a slight increase above the epidemic threshold for influenza activity has been observed, while RSV and SARS-CoV-2 circulation remains at low levels. In Panama, ILI and SARI cases have shown an increase over the last four EWs, coinciding with influenza activity rising to moderate levels. proportion of positive RSV and influenza cases has been observed. Influenza activity has remained low over the last four EWs with a fluctuating trend. During this period, the predominant influenza viruses have been type A(H3N2), with concurrent circulation of influenza A(H1N1)pdm09. RSV activity has remained at moderate levels, with a growing trend. SARS-CoV-2 activity has remained low. By country: In Colombia, SARI activity has remained at epidemic levels over the last four weeks, with most positive cases attributable to RSV and influenza, and ARI cases have risen to extraordinary levels. In Ecuador, SARI activity remains at epidemic levels, with positive cases attributable to RSV and, to a lesser extent, influenza. In Venezuela, over the last four EWs, fluctuating influenza activity around the epidemic threshold has been observed. Brazil and the Southern Cone: After the increase observed in previous weeks, ILI and SARI activity has declined over the last four EWs, particularly due to activity in Brazil, where most positive cases are attributable to influenza and RSV. However, influenza activity has increased over the same period, reaching epidemic levels in most countries. The predominant influenza viruses during this time have been type A(H3N2), with lesser circulation of influenza A(H1N1)pdm09. RSV activity has remained low but has shown a slight increase. SARS-CoV-2 activity has continued to decline, staying at low levels. By country: In Argentina, ILI levels are around the epidemic threshold, while SARI activity remains below this threshold. Influenza activity has increased to moderate levels, and there has also been an increase in the RSV positivity rate. In Brazil, after moderate SARI activity in previous weeks, it has now declined below the epidemic threshold. The highest proportion of positive cases is attributable to RSV, followed by influenza. Meanwhile, ILI cases, which had previously reached high levels, have begun to decline, with influenza responsible for the majority of positive results. In Chile, both ILI and SARI cases have increased over the last four EWs, reaching extraordinary and epidemic levels respectively. Most positive cases are attributable to influenza, which is circulating at extraordinary levels. In Paraguay, SARI activity has exceeded the epidemic threshold, while ILI activity, although increasing, remains below this threshold. Most positive cases are attributable to influenza,circulating at epidemic levels. SARS-CoV-2 and RSV circulation remains stable at low levels. In Uruguay, SARI activity is at moderate and increasing levels, with most positive cases attributable to influenza, which is also at moderate levels.