Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 20 (24 May 2024)

[WEEKLY SUMMARY]. Regional Situation: During the last four epidemiological weeks (EWs), low levels of Influenza-Like Illness (ILI) activity have been observed across the Americas. Meanwhile, there has been moderate activity of Severe Acute Respiratory Infection (SARI), particularly related to the activity observed in Brazil and the Southern Cone. In both cases, the observed activity has been associated with positive cases of influenza and RSV. Regarding the circulation of respiratory viruses, SARS-CoV-2 activity at the regional level has declined to low levels compared to previous epidemic waves. Additionally, there has been an epidemic level of influenza activity for this time of year and low levels of Respiratory Syncytial Virus (RSV) activity. North America: ILI cases have been decreasing over the past four EWs, remaining low and mostly attributable to influenza. Hospitalizations related to respiratory viruses have also decreased and remain low. Influenza activity has continued to decline, staying below the epidemic threshold. During this period, the predominant influenza viruses have been of the B/Victoria type, 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 hovered around the epidemic threshold with a gradual decline, and RSV activity has remained low. In Mexico, influenza circulation has fallen below the epidemic threshold, and SARS-CoV-2 circulation has decreased to low levels. In the United States, ILI cases have decreased and remain low. Hospitalization rates for influenza, RSV, and SARS-CoV-2 have shown a downward 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 last four weeks, with most positive cases attributable to influenza and, to a lesser extent, SARS-CoV-2. Influenza activity has remained fluctuating 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, while SARS-CoV-2 activity has shown a marked increase in the last two weeks. By country: influenza activity has been observed over the last four EWs in Belize, 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 cases have remained low over the last four EWs, although showing a slight increase, with most positive cases attributable to influenza. Influenza activity has seen a slight increase during this period, reaching intermediate levels. In the last four EWs, the predominant influenza viruses have been of type A(H3N2), with concurrent circulation of influenza A(H1N1)pdm09. RSV and SARS-CoV-2 have remained at low levels. By country: In El Salvador, SARI activity has remained at epidemic levels, accompanied by epidemic influenza activity. In Guatemala, during the last four EWs, stable ILI and SARI activity oscillating around the epidemic threshold has been observed, with most positive cases attributable to influenza, which is declining at epidemic levels. In Honduras, fluctuating SARI activity around epidemic levels has been noted over the past four EWs, associated with positive influenza cases at moderate levels. In Nicaragua, RSV, influenza, and SARS-CoV-2 have circulated 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. Andean region: ILI activity has remained stable at low levels over the past four EWs. SARI cases have remained stable with low levels, but an increase in the proportion of positive RSV cases, and to a lesser extent, influenza, 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 low but with a growing trend. SARS-CoV-2 activity has continued to decline, remaining at low levels. 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. In Ecuador, SARI activity has remained at epidemic levels, with positive cases attributable to RSV and, to a lesser extent, influenza. In Peru, influenza activity has fluctuated around the epidemic threshold, and SARS-CoV- 2 activity has declined to low levels. In Venezuela, over the last four EWs, fluctuating influenza activity around the epidemic threshold has been observed. Brazil and the Southern Cone: ILI and SARI cases have increased over the last four EWs, reaching intermediate-high levels, with most positive cases attributable to influenza and RSV. Influenza activity has increased over the last four EWs, reaching epidemic levels in most countries. During this period, the predominant influenza viruses have been type A(H3N2) and, to a lesser extent, A(H1N1)pdm09. RSV activity has remained low but with a slight increase. SARS-CoV-2 activity has continued to decline, remaining at low levels. By country: in Argentina, ILI and SARI levels have remained below the epidemic threshold. Influenza activity has increased, surpassing the epidemic threshold, and an increase in the RSV positivity rate has been observed, while the SARS-CoV-2 positivity rate has remained low. In Brazil, moderate SARI activity has been observed over the last four weeks, currently declining, with the highest proportion of positive cases attributable to RSV, followed by influenza. ILI cases, after reaching high levels, have started to decline, with most positive cases attributable to influenza. In Chile, both ILI and SARI cases have increased over the last four EWs, reaching extraordinary and epidemic levels respectively, with most positive cases attributable to influenza circulating at extraordinary levels. In Paraguay, SARI activity has exceeded the epidemic threshold, while ILI activity, although increasing, has remained 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 has exceeded the epidemic threshold, with most positive cases attributable to influenza, which has surpassed the epidemic threshold.