Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 19 (17 May 2024)

[WEEKLY SUMMARY]. Regional Situation: Over the past four epidemiological weeks (EWs), low activity levels of Influenza-Like Illness (ILI) have been noted across the Americas. Simultaneously, there has been a reduction in Severe Acute Respiratory Infection (SARI) activity, which also remains low. These trends are largely associated with confirmed cases of influenza and, to a lesser extent, SARSCoV- 2. Regionally, SARS-CoV-2 activity has decreased to low levels compared to previous epidemic waves. Additionally, influenza epidemic activity has been observed for this time of year, while Respiratory Syncytial Virus (RSV) activity is declining and currently at low levels. North America: ILI cases have continued to decline over the past four EWs, reaching intermediate-low levels, with most cases attributed to influenza. Hospitalizations associated with respiratory viruses have also declined and remain low. Influenza activity has stayed at epidemic levels, showing a decrease over the last four EWs. During this period, the predominant influenza viruses have been B/Victoria, with lesser circulation of influenza A(H3N2) and A(H1N1)pdm09. RSV activity has decreased over the past four EWs, remaining at low levels. SARS-CoV-2 activity has remained low, though with a slight increase. By country: In Canada, SARS-CoV-2 activity has stayed low. Influenza activity has remained at epidemic levels but is gradually declining, and RSV activity has continued to decrease, remaining low. In Mexico, influenza circulation has fluctuated at epidemic levels over the past four EWs, and SARS-CoV-2 circulation has decreased to low levels. In the United States, influenza activity has decreased to low levels over the past four EWs. Both RSV and SARS-CoV-2 have remained at low levels. ILI cases have shown a decline and remain at medium-low levels. Hospitalization rates for influenza, RSV, and SARS-CoV-2 have shown a decreasing trend over the past four EWs, reaching low levels. Caribbean: ILI and SARI cases have continued to decline over the past four weeks, with most positive cases attributed to influenza and, to a lesser extent, SARS-CoV-2. Influenza activity has fluctuated at low levels over the past 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 over the past two weeks. By country: Influenza activity has been observed over the past four EWs in Belize, Guyana, and the Cayman Islands. SARS-CoV- 2 activity has been noted in Barbados and the Cayman Islands. Central America: Over the past four EWs, both ILI and SARI activity has remained low, though with a slight increase, with most positive cases attributed to influenza. Influenza activity has shown a slight increase during this period, reaching intermediate levels. Over the past four EWs, the predominant influenza viruses have been A(H3N2) with concurrent circulation of A(H1N1)pdm09. RSV and SARS-CoV-2 activity have remained low. By country: In El Salvador, SARI activity is around epidemic levels with low circulation of SARS-CoV-2 and fluctuating influenza activity around the epidemic threshold. In Guatemala, during the past four EWs, ILI and SARI activity has been stable at epidemic levels, associated with positive influenza cases circulating at moderate levels. In Honduras, during the past four EWs, SARI activity has fluctuated around epidemic levels, associated with positive influenza cases circulating at epidemic levels and in decline. In Nicaragua, RSV, influenza, and SARS-CoV-2 activity are at low levels. In Panama, ILI and SARI cases have shown an increase over the past four EWs, with influenza activity at epidemic levels. Andean Region: ILI activity has remained stable at low levels over the past four EWs. SARI cases have remained stable at low levels; however, there has been an increase in the proportion of positive cases for RSV and, to a lesser extent, influenza. Influenza activity has remained at low levels over the past four EWs with a fluctuating trend. During this period, the predominant influenza viruses have been type A(H3N2) with concurrent circulation of type A(H1N1)pdm09. RSV activity has remained at low levels, though with an increasing trend. SARS-CoV-2 activity has continued to decline, remaining at low levels. By country: In Colombia, RSV activity, although low, has increased over the past four EWs; SARS-CoV-2 activity has decreased to low levels, and influenza activity has remained below the epidemic threshold with a slight increase. SARI activity has hovered around the epidemic threshold during this period, with positive cases attributed to RSV and influenza. In Ecuador, following a marked increase in RSV activity in previous EWs, there has been a decline to medium levels; SARS-CoV-2 activity has decreased to low levels, and influenza activity has risen above the epidemic threshold. SARI activity is at epidemic levels, with most positive cases attributed to RSV and, to a lesser extent, influenza. In Peru, influenza activity is fluctuating around the epidemic threshold, and SARS-CoV-2 activity has decreased to low levels. In Venezuela, during the past four EWs, influenza activity has fluctuated around the epidemic threshold. Brazil and the Southern Cone: ILI and SARI activity have increased over the past four EWs to intermediate-high levels, with most positive cases attributed to influenza. Influenza activity has increased over the past 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, though 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 to levels above the epidemic threshold, and the positivity rate for SARS-CoV-2 has continued to decline, reaching low levels. There has also been a slight increase in the positivity rate for RSV. In Brazil, SARS-CoV-2 activity has continued to decline, reaching low levels, and influenza activity remains below the epidemic threshold. In Chile, both ILI and SARI cases have increased over the past four EWs, reaching extraordinary and epidemic levels, respectively, with most positive cases attributed to influenza circulating at extraordinary levels. In Paraguay, SARI activity has exceeded the epidemic threshold, and ILI activity has remained below this threshold. Influenza activity is at epidemic levels; SARS-CoV-2 and RSV circulation remain stable at low levels. In Uruguay, SARI activity has exceeded the epidemic threshold, with most positive cases attributed to SARS-CoV-2 and influenza, whose activity has exceeded the epidemic threshold.