Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 26 (5 July 2024)

[WEEKLY SUMMARY]. Regional Situation: During the last four epidemiological weeks (EWs), low levels of Influenza-Like Illness (ILI) activity have been recorded in the Americas region. However, epidemic activity has been reported in the Southern Cone and an increase in activity in the Caribbean and Central America subregions. This activity is associated with the circulation of influenza in the Southern Cone, Central America, and the Caribbean, as well as SARS-CoV-2 in the Caribbean. Additionally, a decrease in Severe Acute Respiratory Infection (SARI) activity has been observed after reaching epidemic levels in the Southern Cone, Andean subregion, and Central America, which is now in decline. This activity has been linked to positive cases of influenza and RSV. At the regional level, SARS-CoV-2 activity has remained at low levels compared to previous epidemic waves, although it has shown an increase associated with circulation in North America and the Caribbean. Likewise, a declining epidemic influenza activity has been observed, marked by circulation in Central America, the Southern Cone, and some Caribbean countries. RSV activity has remained at low levels, except in the Andean region and the Southern Cone, where epidemic levels and a rising trend have been observed. North America: Cases of ILI, SARI, and hospitalizations associated with respiratory viruses have remained at low levels during the last four EWs. Influenza activity has stayed below the epidemic threshold in all countries. During this period, the predominant influenza viruses have been of type B/Victoria, followed by type A(H3N2) and A(H1N1)pdm09. RSV activity has remained at low levels. SARS-CoV-2 activity has shown an increase, although still at low levels compared to previous waves. By Country: • Canada: SARS-CoV-2 activity has risen to medium levels compared to previous waves. Influenza activity has decreased below the epidemic threshold, and RSV activity has remained low. • Mexico: Cases of ILI and SARI remain stable at epidemic levels, with positive cases attributable to SARS-CoV-2, whose activity is on the rise, and influenza, whose activity has decreased below the epidemic threshold. • United States: Hospitalization rates for influenza, RSV, and SARS-CoV-2 remain at low levels, although there has been a slight increase associated with positive SARS-CoV-2 cases. Both influenza and RSV activity remain at low levels. Caribbean: In the last four EWs, ILI cases have increased, associated with a higher proportion of positive cases of SARS-CoV-2 and influenza. On the other hand, although SARI cases have remained at low levels, an increase in the count and proportion of positive cases of SARS-CoV-2 and influenza has been observed. Influenza activity has remained at 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. RSV activity has remained at low levels. SARS-CoV-2 activity has shown a marked increase in the last four EWs, reaching high levels compared to previous waves. By Country: Influenza activity has been observed in the last four EWs in the Dominican Republic, Guyana, and the Cayman Islands. SARS-CoV-2 activity has been observed in Belize, the Dominican Republic, Jamaica, Suriname, Barbados, Guyana, and the Cayman Islands. • Dominican Republic: An increase in SARI activity has been observed with epidemic levels, coinciding with epidemic influenza activity. • Jamaica: An increase in SARI cases has been observed above the epidemic threshold, coinciding with a marked increase in SARS-CoV-2 activity. • Guyana: An increase in ILI and SARI cases has been observed with positive cases attributable to both SARS-CoV-2 and influenza. Central America: After showing an increase in previous weeks in ILI and SARI activity, a decrease has been observed in the last three EWs, with most positive cases attributable to influenza. Influenza activity has shown an increase during this period, reaching epidemic levels in several countries of 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: • El Salvador: Influenza circulation, after reaching high levels, has decreased to moderate levels, and SARS-CoV-2, after showing a slight increase, remains at low levels compared to previous waves. • Guatemala: An increase above the epidemic threshold has been observed in ILI and SARI activity. Most positive ILI cases are attributable to influenza, whose circulation has decreased to epidemic levels, and SARI cases to RSV, whose activity is on the rise. • Honduras: In the last four EWs, SARI activity has been fluctuating and remains at epidemic levels. This is mainly associated with positive influenza cases, currently at moderate levels, and to a lesser extent to SARS-CoV-2, which is on the rise. • Nicaragua: An increase above the moderate threshold of influenza activity has been observed, while RSV and SARS-CoV-2 circulation remains at low levels. • Panama: ILI and SARI cases have shown an increase in the last four EWs, coinciding with influenza activity that, after reaching moderate levels, has decreased to epidemic levels in the last EW. Andean: ILI and SARI activity has remained stable at low levels during the last four EWs. However, an increase in the proportion of positive RSV and SARS-CoV-2 cases has been observed. Influenza activity has remained at low levels in 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 and type B/Victoria. RSV activity has remained at moderate levels, with a rising trend. SARS-CoV-2 activity has remained at low levels, showing a slight increase. By Country: • Bolivia: SARI cases are in decline, with levels below the epidemic threshold. Almost all positives are attributable to influenza, whose activity has decreased to levels below the epidemic threshold after reaching moderate levels. • Colombia: SARI activity, after reaching epidemic levels during the last weeks, has shown a decline 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 attributable to influenza, whose activity is below the epidemic threshold. ARI (Acute Respiratory Infection) cases have reached extraordinary levels. • Ecuador: SARI and pneumonia activity has shown an increase in the last EWs, reaching moderate levels. Most positive SARI cases are attributable to influenza, whose activity is on the rise and has surpassed the epidemic threshold. To a lesser extent, cases are attributable to RSV, which is in decline, and SARS-CoV-2, which is on the rise. • Venezuela: After reaching epidemic activity in previous weeks, a decline below this threshold has been observed. Brazil and the Southern Cone: After the increase observed in previous weeks, ILI and SARI activity has shown a decline in the last four EWs, with most positive cases attributable to influenza and RSV, respectively. Influenza activity is at epidemic levels in most countries, although showing a decreasing trend. During this period, the predominant influenza viruses have been of type A(H3N2) and, to a lesser extent, A(H1N1)pdm09. RSV activity, although on the rise, has remained at low levels compared to previous seasons. SARS-CoV-2 activity has remained at low levels. By Country: • Argentina: ILI activity, after reaching moderate 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 decline in the last week to moderate levels. At the same time, an increase in RSV positivity has been observed, although it remains below the maximum values reached in previous seasons. • 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. • Chile: ILI and SARI cases, after reaching extraordinary levels this season, are currently declining, at moderate and epidemic levels, respectively. Most positive cases during the last four EWs are attributable to RSV, whose activity is on the rise, although at levels below those observed in previous seasons. Influenza activity, after reaching extraordinary levels, has decreased to epidemic levels. • 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, which circulates at levels below those observed in previous seasons. • Uruguay: SARI activity, after reaching high levels, has decreased to moderate levels, with most positive cases attributable to RSV and influenza. The latter, after reaching moderate levels, has decreased to epidemic levels. RSV activity has shown an increase, although it circulates at levels below those observed in previous seasons.