Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 27 (12 July 2024)

[WEEKLY SUMMARY]. Regional Situation: During the last four epidemiological weeks (EW), low levels of Influenza-Like Illness (ILI) activity have been reported in the Americas. However, there has been epidemic activity in the Southern Cone and increased activity in the Caribbean and Central America subregions. This is due to the circulation of influenza in the Southern Cone, Central America, and the Caribbean, as well as SARS-CoV-2 in the Caribbean. Additionally, there has been a decrease in Severe Acute Respiratory Infection (SARI) activity after reaching epidemic levels in the Southern Cone, the Andean subregion, and Central America, related to positive cases of influenza and RSV. Regarding respiratory virus circulation, at the regional level, SARS-CoV-2 activity has remained low compared to previous epidemic waves, although it has shown an increase associated with circulation in North America and the Caribbean. Influenza activity has been declining, especially in the Southern Cone, but has been increasing in Central America. Respiratory Syncytial Virus (RSV) activity has remained low, except in the Andean region and the Southern Cone, where epidemic levels and an increasing trend have been observed. North America: ILI, SARI, and hospitalizations associated with respiratory viruses have remained low during the last four EW, although there has been an increase in the proportion of positive SARS-CoV-2 cases. Influenza activity has remained below the epidemic threshold in all countries. The predominant influenza viruses during this period have been type B/Victoria, followed by type A(H3N2) and A(H1N1)pdm09. RSV activity has remained low. SARS-CoV-2 activity has shown an increase, although it remains low compared to previous waves. By country: • In Canada, SARS-CoV-2 activity has increased, reaching moderate levels compared to previous waves. Influenza activity remains below the epidemic threshold, and RSV activity has remained low. • In Mexico, ILI and SARI cases remain stable at epidemic levels, with an increase in positive cases attributable to SARS-CoV- 2, whose activity is on the rise. Influenza activity remains below the epidemic threshold. • In the United States, hospitalization rates for influenza, RSV, and SARS-CoV-2 remain low, although there has been a slight increase in positive SARS-CoV-2 cases. Both influenza and RSV activity remain low. Caribbean: In the last four EWs, ILI cases have increased, associated with a higher proportion of positive SARS-CoV-2 and influenza cases. Although SARI cases have remained low, there has been an increase in the proportion of positive SARS-CoV-2 and influenza cases. Influenza activity has remained at intermediate 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. RSV activity has remained low. SARS-CoV-2 activity remains elevated but shows a decreasing trend. By country: • Influenza activity has been observed in the last four EWs in the Dominican Republic, Jamaica, Guyana, and the Cayman Islands. • SARS-CoV-2 activity has been observed in Belize, the Dominican Republic, Jamaica, Suriname, Barbados, Guyana, the Cayman Islands, and Saint Vincent and the Grenadines. • In the Dominican Republic, SARI activity has increased to epidemic levels, coinciding with an epidemic of influenza, which is currently declining. • In Jamaica, SARI cases have increased above the epidemic threshold, coinciding with a marked increase in SARS-CoV-2 and influenza activity. • In Guyana, ILI and SARI cases have increased, with positive cases attributable to both SARS-CoV-2 and influenza. Central America: ILI and SARI activity remain fluctuating at epidemic levels, with most positive cases attributable to influenza, followed by SARS-CoV-2 and RSV. Influenza activity has increased during the last four EWs, reaching epidemic levels in several countries in the subregion. During this period, the predominant influenza viruses have been type A(H3N2), with concurrent circulation of A(H1N1)pdm09. RSV and SARS-CoV-2 activity, although increasing, remain low. By country: • In El Salvador, influenza circulation, after reaching high levels, has declined to moderate levels, and SARS-CoV-2, after showing a slight increase, remains low compared to previous waves. • In Guatemala, ILI and SARI activity has increased above the epidemic threshold. Most positive ILI cases are attributed to influenza, whose circulation has declined to epidemic levels, and SARI cases to RSV, whose activity is on the rise. • In Honduras, SARI activity has been fluctuating in the last four EWs and remains at epidemic levels. This is mainly associated with positive influenza cases, currently at moderate levels, and to a lesser extent with SARS-CoV-2, which is on the rise. • In Nicaragua, influenza activity has increased above the high threshold, while RSV and SARS-CoV-2 circulation remains low. • In Panama, ILI and SARI cases have increased in the last four EWs, coinciding with influenza activity that, after reaching moderate levels, has declined to epidemic levels in the last EW. Andean Region: ILI and SARI activity has remained stable at low levels during the last four EWs. However, there has been an increase in the proportion of positive RSV and influenza cases. Influenza activity has remained low in the last four EWs, with a fluctuating trend. During this period, the predominant influenza viruses have been type A(H3N2), with concurrent circulation of A(H1N1)pdm09 and type B/Victoria. RSV activity has remained at moderate levels, with an increasing trend. SARS-CoV-2 activity has remained low, showing a slight increase. By country: • In Bolivia, SARI cases are decreasing, with levels below the epidemic threshold. Almost all positives are attributable to influenza, whose activity has decreased to levels below the epidemic threshold. • In Colombia, SARI activity, after reaching epidemic levels in recent weeks, has decreased below this threshold, with most positive cases attributable to RSV, whose activity is at intermediate levels compared to previous seasons. To a lesser extent, positive cases are attributed to influenza, whose activity is below the epidemic threshold but increasing. ARI (Acute Respiratory Infection) cases have reached extraordinary levels. • In Ecuador, SARI and pneumonia activity has increased in recent EWs, reaching moderate levels. Positive SARI cases are mainly attributable to influenza, whose activity is at epidemic levels. To a lesser extent, they are attributed to RSV, which is declining, and SARS-CoV-2, which is increasing. • In Peru, influenza activity has decreased to levels below the epidemic threshold. At the same time, increasing RSV and SARS-CoV-2 activity has been observed, although it remains low. • In Venezuela, influenza activity has decreased to levels below the epidemic threshold. Brazil and the Southern Cone: After the increase observed in previous weeks, ILI and SARI activity has decreased in the last four EWs, with most positive cases attributable to influenza and RSV. Influenza activity is at epidemic levels in most countries, although showing a decreasing trend. During this period, the predominant influenza viruses have been type A(H3N2) and, to a lesser extent, A(H1N1)pdm09. RSV activity, although increasing, has remained at lower levels compared to previous seasons. SARS-CoV-2 activity has remained low. By country: • In Argentina, ILI activity, after reaching high levels, has decreased to epidemic levels, while SARI activity, after reaching epidemic levels, has decreased below this threshold. Influenza activity has reached extraordinary levels, showing a decrease in the last four EWs to moderate levels. At the same time, an increase in the positivity rate of RSV has been observed, although it remains below the maximum values reached in previous seasons. • In Brazil, ILI and SARI activity has decreased to levels below the epidemic threshold, with the highest proportion of positive cases attributed to RSV and influenza. • In Chile, ILI and SARI cases, after reaching extraordinary levels this season, are currently decreasing, at moderate and epidemic levels, respectively. Most positive cases during the last four EWs are attributable to RSV, whose activity is increasing, although at levels below those observed in previous seasons. Influenza activity, after reaching extraordinary levels, has decreased to levels below the epidemic threshold. • In Paraguay, SARI activity, after reaching moderate levels, has decreased to epidemic levels, and ILI activity, after reaching epidemic levels, has decreased below this threshold. Most positive cases are attributable to influenza, which circulates at epidemic levels, and to a lesser extent to RSV, whose circulation is increasing although at levels below those observed in previous seasons. • In Uruguay, SARI activity, after reaching high levels, has decreased to moderate levels, with most positive cases attributable to RSV and to a lesser extent influenza. The latter, after reaching moderate levels, has decreased to epidemic levels. RSV activity has shown an increase, reaching levels similar to the peaks observed in previous seasons.