Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 14 (12 April 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, with a decreasing trend primarily associated with moderate activity in North America. Concurrently, a decrease in Severe Acute Respiratory Infection (SARI) activity has been noted, currently at low levels. In both cases, the observed activity has been linked to positive cases of influenza and SARS-CoV-2. Regarding the circulation of respiratory viruses, regional SARS-CoV-2 activity has decreased to low levels compared to previous epidemic waves. Additionally, epidemic influenza activity for this time of year has remained stable, while Respiratory Syncytial Virus (RSV) activity has been declining and is currently at low levels. North America: Cases of ILI have been declining over the past four EWs, maintaining intermediate levels, with the majority attributable to influenza. SARI cases and hospitalizations associated with respiratory viruses have also been decreasing. Influenza activity has remained at epidemic levels, showing a decline over the last four EWs. Predominant influenza viruses during this period have been of the B/Victoria type, with concurrent circulation of influenza A(H1N1)pdm09 and influenza A(H3N2). RSV activity has decreased over the past four EWs, remaining at low levels. SARS-CoV-2 activity has decreased over the last four EWs to low levels compared to previous waves. By country: In Canada, SARS-CoV-2 activity has markedly declined over the last four EWs to low levels. Influenza activity has remained at epidemic levels with a gradual decline, and RSV activity has remained low. In Mexico, influenza circulation has fluctuated at epidemic levels over the past four EWs, and SARS-CoV-2 circulation has decreased to moderate-low levels. In the United States, influenza activity has declined over the last four EWs but remains above the epidemic threshold. Both RSV and SARS-CoV-2 have maintained a decreasing trend to low levels. ILI cases have shown a decline and remain at moderate levels. Hospitalization rates for influenza, RSV, and SARS-CoV-2 have shown a decreasing trend over the last four EWs, with low levels. Caribbean: Following an increase observed in previous EWs, ILI cases have shown a decline in the last four weeks. SARI cases have remained on a downward trend, with the majority of positive cases attributable to influenza. Influenza activity has remained fluctuating at low levels over the last four EWs. During this period, predominant viruses have been of the A(H1N1)pdm09 type, with concurrent circulation of influenza A(H3N2) and B/Victoria to a lesser extent. RSV activity has remained at low levels. SARSCoV- 2 activity has remained at low levels. By country: In the last four EWs, influenza activity has been observed in Belize and the Cayman Islands. SARS-CoV-2 activity has been observed in Barbados, Guyana, and St. Vincent and the Grenadines. Central America: ILI and SARI activity have remained low over the last four EWs, with a slight increase, with the majority of positive cases attributable to influenza. Influenza activity has shown a slight increase during this period, reaching intermediatelow levels. In the last four EWs, predominant influenza viruses have been of the A(H1N1)pdm09 type with concurrent circulation of A(H3N2). RSV and SARS-CoV-2 activity have remained at low levels. By country: In El Salvador, SARI activity is around epidemic levels with low-level SARS-CoV-2 circulation and influenza activity fluctuating around the epidemic threshold. In Guatemala, an increase in ILI and SARI cases has been observed associated with an increase in positive influenza cases, showing extraordinary and moderate activity respectively. In Honduras, an increase in SARI cases has been observed over the last four EWs, reaching epidemic levels, associated with an increase in positive influenza cases, with moderate activity. In Nicaragua, RSV, influenza, and SARS-CoV-2 activity are at low levels. In Panama, influenza activity fluctuates around the epidemic threshold, and ILI and SARI cases have increased over the last four EWs. Andean Region: ILI activity has remained stable at low levels, with the majority of positive cases attributable to influenza and SARS-CoV-2. SARI cases have remained on a downward trend at low levels, with the majority of positive cases attributable to RSV. Influenza activity has remained at low levels over the last four EWs with a slightly increasing trend. During this period, predominant influenza viruses have been of the A(H3N2) type with concurrent circulation of A(H1N1)pdm09. RSV activity has remained at low levels, with a slight increase. SARS-CoV-2 activity has remained on a downward trend at low levels. By country: In Colombia, SARS-CoV-2 activity has decreased over the last four EWs to low levels, while influenza and RSV activity have remained fluctuating at low levels. SARI activity has remained on a downward trend around the epidemic threshold over the last four EWs, with positive cases attributable to RSV and influenza. In Ecuador, a marked increase in RSV activity to high levels has been observed, SARS-CoV-2 has decreased to moderate-low levels, and influenza activity has remained below the epidemic threshold. SARI activity has fluctuated around the moderate threshold, with positive cases attributable to RSV in the last four EWs. In Peru, influenza activity is fluctuating around the epidemic threshold, and SARSCoV- 2 activity has decreased to low levels. In Venezuela, a marked increase in influenza activity above the epidemic threshold has been observed over the last four EWs. Brazil and Southern Cone: ILI and SARI activity have increased over the last four EWs, with the majority of positive cases attributable to SARS-CoV-2 and, to a lesser extent, influenza. Influenza activity has increased over the last four EWs, reaching epidemic levels in some countries. During this period, predominant influenza viruses have been of the A(H3N2) type followed by A(H1N1)pdm09. RSV activity has remained at low levels. SARS-CoV-2 activity has remained on a decreasing trend with intermediate-low activity levels. By country: In Argentina, ILI and SARI levels have remained below the epidemic threshold. Influenza activity has shown a slight increase above the epidemic threshold, and the percentage of SARS-CoV-2 positivity has remained on a decreasing trend at low levels. In Brazil, SARS-CoV-2 activity continues to decrease, remaining at low levels, and influenza activity fluctuates around the epidemic threshold. In Chile, both ILI and SARI cases have increased over the last four EWs, reaching epidemic levels; the majority of positive cases are attributable to SARS-CoV-2 and influenza. SARS-CoV-2 activity has decreased to low levels, and influenza activity has shown a pronounced increase above the epidemic threshold. In Paraguay, SARI activity has remained around the epidemic threshold, and ILI activity has remained below this threshold. Influenza activity has shown a slight increase, fluctuating around the epidemic threshold; SARS-CoV-2 circulation has decreased over the last four EWs, reaching low levels, and RSV activity has remained low. In Uruguay, SARI activity has exceeded the epidemic threshold, with the majority of positive cases attributable to SARS-CoV-2, which is at moderate and decreasing levels.