Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 23 (14 June 2024)

ABSTRACT

[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. At the same time, moderate levels of Severe Acute Respiratory Infection (SARI) have been reported, particularly in Brazil and the Southern Cone, followed by the Andean subregion. Both have been linked to positive cases of influenza and RSV. Regarding the circulation of respiratory viruses, SARS-CoV-2 activity has remained at low levels compared to previous epidemic waves, although showing a slight increase associated with circulation in North America and the Caribbean. Additionally, there has been increasing epidemic-level influenza activity, marked by circulation in Central America, Brazil, the Southern Cone, and some Caribbean countries. RSV activity has remained low except in the Andean region, where moderate levels have been observed. 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 of type A(H3N2), followed by type B/Victoria, and type A(H1N1)pdm09. RSV activity has shown a decline, 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, and SARS-CoV-2 activity has shown a slight increase. In the United States, both ILI cases and hospitalization rates for influenza, RSV, and SARS-CoV-2 remain low. While influenza and RSV activity is low, the SARS-CoV-2 positivity rate has shown a slight increase. 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 shown an increase to intermediate levels during the last four EWs. During this period, the predominant viruses have been of 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 compared to previous waves. By country Influenza activity has been observed over the last four EWs in the Dominican Republic, Jamaica, Guyana, and the Cayman Islands. SARS-CoV-2 activity has been noted in Jamaica, Barbados, Guyana, and the Cayman Islands. Central America Both ILI and SARI activity have increased over the last four EWs, with most positive cases attributable to influenza. Influenza activity has risen during this period, reaching epidemic levels in several countries in the subregion. In the last four EWs, the predominant influenza viruses have been of type A(H3N2), with concurrent circulation of A(H1N1)pdm09. RSV and SARS-CoV-2 activity have 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 activity have fluctuated around the epidemic threshold, with most positive cases attributable to influenza, which is at epidemic levels, and RSV, whose activity is increasing. 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 extraordinary levels. Andean ILI and SARI activity have remained stable at low levels over the past four EWs, although an increase in the 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 of type A(H3N2), with concurrent circulation of A(H1N1)pdm09. RSV activity has remained at moderate levels, with a growing trend. SARS-CoV-2 activity has remained low. By country In Bolivia, SARI cases are in decline, with levels below the epidemic threshold. Almost all positive cases are attributable to influenza, whose activity has decreased to below the epidemic threshold after having reached moderate levels. In Colombia, SARI activity has remained at epidemic levels during the last four weeks, with most positive cases attributable to RSV (which is increasing) and, to a lesser extent, influenza (which is below the epidemic threshold). ILI cases have risen to extraordinary levels. In Ecuador, SARI activity remains at epidemic levels, showing an increase, while pneumonia levels have risen to moderate levels. Positive SARI cases are attributable to influenza, whose increasing activity has surpassed the epidemic threshold, and to a lesser extent, RSV, which is in decline. In Peru, influenza activity remains below the epidemic threshold, while RSV and SARS-CoV-2 activity also remain low. In Venezuela, during 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, SARI activity has declined over the last four EWs, particularly in Brazil, with most positive cases attributable to influenza and RSV. However, ILI activity continues to rise, with most positive cases attributed to influenza. Influenza activity has increased over the last four EWs, reaching epidemic levels in most countries. During this period, the predominant influenza viruses have been of type A(H3N2), with lesser circulation of 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 activity is on the rise with moderate levels, while SARI activity remains below the epidemic threshold. Influenza activity has shown an increase, reaching extraordinary levels. 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 reached extraordinary and epidemic levels respectively and are currently in decline; most positive cases are attributable to influenza, which circulates at moderate levels and has shown a decrease. In Paraguay, SARI activity is at moderate levels, while ILI activity is around the epidemic threshold. Most positive cases are attributable to influenza, circulating at moderate levels, and to a lesser extent, RSV, which is circulating at levels below those observed in previous seasons. In Uruguay, SARI activity is at high and increasing levels, with most positive cases attributable to influenza, which has reached moderate levels, and to a lesser extent, RSV, which is circulating at levels below those observed in previous seasons.