Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 22 (7 June 2024)

[WEEKLY SUMMARY]. Regional Situation: Over the past four epidemiological weeks (EWs), intermediate levels of Influenza-Like Illness (ILI) activity have been observed in the Americas region. Additionally, a decrease in Severe Acute Respiratory Infection (SARI) activity has been noted, currently at low levels. In both cases, the observed activity has been associated with positive cases of influenza and SARS-CoV-2. ILI activity has been primarily linked to moderate activity observed in North America and elevated activity observed in the Caribbean, while SARI activity has been particularly influenced by detected activity in North America. Regarding the circulation of respiratory viruses, a regional rise in SARS-CoV-2 activity has been observed, remaining moderate compared to previous epidemic waves. Likewise, epidemic influenza activity has been observed for this time of year, with moderate Respiratory Syncytial Virus (RSV) activity showing a decrease over the last four EWs. North America: ILI cases, following a slight decrease in previous EWs, have remained at medium-high levels, with most cases attributable to influenza. SARI cases have continued to decline. Influenza activity has remained at epidemic circulation levels, showing a slight decrease over the last four EWs. During this period, predominant influenza viruses have been A(H1N1)pdm09 and influenza A(H3N2), with lesser circulation of influenza B/Victoria. RSV activity has shown a decrease over the last four EWs, remaining at moderate levels. SARS-CoV-2 activity has decreased over the last four EWs to low levels compared to previous waves. By countries: In Canada, SARS-CoV-2 activity has markedly decreased over the last four EWs to medium-low levels. Influenza activity has remained at epidemic levels with a gradual decrease, and RSV activity has also decreased to moderate levels. In Mexico, influenza circulation has fluctuated at epidemic levels over the last four EWs, while SARS-CoV-2 circulation has remained at intermediate levels compared to previous waves. In the United States, influenza activity has remained consistently above the epidemic threshold, while RSV and SARS-CoV-2 activity have decreased to low levels over the last four EWs. ILI cases have remained stable at medium levels. Hospitalization rates for influenza, RSV, and SARS-CoV-2, after reaching similar elevated levels as the previous season, have shown a downward trend over the last four EWs. Caribbean: Following the increase observed in previous EWs, ILI cases have shown a decrease in the last four weeks, with positive cases for influenza. SARI cases have remained on the decline, with the majority of positive cases attributable to influenza. Influenza activity has shown a decrease in the last four EWs, reaching low circulation levels. Over the last four EWs, predominant viruses have been A(H1N1)pdm09, with concurrent circulation of A(H3N2) and, to a lesser extent, B/Victoria. RSV activity has remained at low levels. SARS-CoV-2 activity has remained on the decline to low levels. By countries: Increased influenza activity has been observed in Suriname. Elevated SARS-CoV-2 activity has been observed in Dominica, Haiti, Saint Lucia, Barbados, and Guyana. Central America: ILI activity has shown a slight decrease in the last four weeks, reaching low activity levels, with most positive cases attributable to influenza. SARI cases have also shown a decrease, reaching low levels, with the majority of positive cases attributable to influenza and, to a lesser extent, SARS-CoV-2. Influenza activity has increased over the last four EWs, although remaining at low levels. During this period, predominant viruses have been A(H1N1)pdm09, with concurrent circulation of A(H3N2) and, to a lesser extent, B/Victoria. RSV activity has remained at low levels. SARS-CoV-2 activity has also remained at low levels. By countries: In El Salvador, SARS-CoV-2 activity has decreased over the last four EWs to low levels. In Guatemala, an increase in ILI cases associated with influenza and, to a lesser extent, SARS-CoV-2 has been observed, reaching moderate activity levels, while SARI cases have remained at epidemic levels. In Honduras, after an increase in ILI and SARI cases associated with positive influenza cases observed in previous weeks, a decrease has been detected in the last four EWs, reaching levels below the epidemic threshold, while influenza activity has remained above this threshold. In Nicaragua, RSV, influenza, and SARS-CoV-2 activity have remained at low levels. In Panama, influenza activity has shown a pronounced increase to moderate levels, while ILI and SARI cases have remained low over the last four EWs. Andean Region: ILI activity has remained stable at low levels, with the majority of positive cases attributable to influenza. SARI cases have continued to decline to low levels, with the majority of positive cases attributable to SARS-CoV-2 and, to a lesser extent, influenza. Influenza activity has remained at low levels over the last four EWs. During this period, predominant influenza viruses have been A(H1N1)pdm09, with concurrent circulation of A(H3N2) and, to a lesser extent, B/Victoria. RSV activity has remained at low levels. SARS-CoV-2 activity has remained on the decline to moderate levels. By countries: In Bolivia, an increase in ILI and SARI cases has been observed, reaching levels around the epidemic threshold associated with positive cases for influenza. Influenza has shown a marked increase in activity, surpassing the elevated threshold. In Colombia, SARS-CoV-2 activity has decreased over the last four EWs to medium-low levels; SARI activity has been around the epidemic threshold during these last four EWs, with positive cases attributable to influenza and, to a lesser extent, SARS-CoV-2 and RSV. In Ecuador, SARS-CoV-2 activity has increased to medium-high levels, influenza activity has remained below the epidemic threshold, and RSV activity has remained at moderate levels over the last four EWs. SARI activity has fluctuated around the moderate threshold, with positive SARI cases attributable to influenza, SARS-CoV-2, and, to a lesser extent, RSV. In Peru, after a marked increase in SARS-CoV-2 activity in previous weeks, a decrease has been shown in the last four EWs to low levels. In Venezuela, fluctuating influenza activity has been observed below the epidemic threshold over the last four EWs. Brazil and Southern Cone: SARI and ILI activity has remained on a decreasing trend and at low levels over the last four EWs, with the majority of positive cases attributable to SARS-CoV-2. Influenza activity has shown an increase over the last four EWs, reaching levels around the epidemic threshold in some countries. During this period, predominant influenza viruses have been A(H3N2) and A(H1N1)pdm09 followed by B/Victoria. RSV activity has remained at low levels. SARS-CoV-2 activity has remained on the decline with elevated levels. By countries: In Argentina, ILI and SARI levels have remained below the epidemic threshold. The positivity rate for SARS-CoV-2, while remaining at elevated levels, has shown a marked decline in the last four EWs. In Brazil, SARS-CoV-2 activity has remained at elevated levels, and influenza activity has shown an increase during the last four EWs, fluctuating around the epidemic threshold. In Chile, an increase in SARS-CoV-2 activity has been observed in the last four EWs at moderate levels, and there has been a rise in influenza activity, which remains around the epidemic threshold. ILI cases have remained at epidemic levels, and SARI cases below this threshold, with the majority attributable to SARS-CoV-2 and to a lesser extent to influenza. In Paraguay, SARS-CoV-2 circulation has shown a decline in the last four EWs, being at low levels, and influenza and RSV activity have remained low. SARI and ILI activity have stayed below the epidemic threshold. In Uruguay, SARI activity has continued at levels below the epidemic threshold, though with a slight increase in the last four weeks, with the majority of the few positive cases attributable to SARS-CoV-2.