Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 16 (26 April 2024)

[WEEKLY SUMMARY]. Regional Situation: Over the last four epidemiological weeks (EWs), intermediate-low levels of Influenza-Like Illness (ILI) activity have been observed in the Americas region, showing a decreasing trend primarily related to activity in North America. There has also been a decrease in Severe Acute Respiratory Infection (SARI) activity, now at low levels. In both cases, the observed activity is primarily associated with influenza and, to a lesser extent, SARS-CoV-2. Regionally, SARS-CoV-2 activity has declined to low levels relative to previous epidemic waves. Similarly, influenza has exhibited expected seasonal epidemic activity, which continues to decrease slightly, alongside a diminishing circulation of Respiratory Syncytial Virus (RSV), now also at low levels. North America: Over the last four EWs, ILI cases have consistently declined, maintaining intermediate-low levels predominantly attributed to influenza. Concurrently, hospitalizations due to respiratory viruses have continued to decrease, remaining at low levels. Influenza has sustained epidemic circulation levels with a downward trend noted during this period. The predominant influenza viruses have been type B/Victoria, with lesser circulation of influenza A(H1N1)pdm09 and A(H3N2). RSV and SARS-CoV-2 activity have similarly shown declines, stabilizing at low level. By country: In Canada, there has been a marked decrease in SARS-CoV-2 activity, now at low levels, while influenza maintains a gradual decline at epidemic levels and RSV continues to decrease. In Mexico, influenza activity has fluctuated at epidemic levels with SARS-CoV-2 activity decreasing to low levels. In the United States, influenza activity has decreased over the past four EWs but remains above the epidemic threshold. Concurrently, both RSV and SARS-CoV-2 activities have continued their decline to low levels. ILI cases are diminishing and maintaining intermediate-low levels, and hospitalization rates for influenza, RSV, and SARS-CoV-2 are on a downward trend. Caribbean: Both ILI and SARI cases have continued to decline over the last four weeks, predominantly involving influenza positive cases and, to a lesser extent, SARS-CoV-2. Influenza activity has shown low-level fluctuations during this period. The predominant viruses have been type A(H1N1)pdm09, with concurrent circulation of influenza A(H3N2) and, to a lesser extent, B/Victoria. Both RSV and SARS-CoV-2 activities have remained low. By country: Influenza activity was observed in Belize, Jamaica, and the Cayman Islands over the last four EWs. SARS-CoV-2 activity was noted in Barbados, Guyana, and Trinidad and Tobago. Central America: Throughout the last four EWs, both ILI and SARI activities have remained low but exhibited a gradual increase, with the majority of cases attributable to influenza. During this time, influenza activity has seen a slight increase but remains at intermediate-low levels. The predominant influenza viruses have been type A(H1N1)pdm09 and A(H3N2). Both RSV and SARS-CoV-2 activity have stayed at low levels. By country: In El Salvador, SARI activity hovers around epidemic levels with low SARS-CoV-2 circulation and fluctuating influenza activity around the epidemic threshold. Guatemala has observed stable ILI and SARI activities at epidemic levels, associated with moderate-level influenza circulation. Honduras has seen fluctuating SARI activity around epidemic levels linked to moderate influenza activity. Nicaragua exhibited low activity levels for RSV, influenza, and SARS-CoV-2. In Panama, both ILI and SARI cases have shown an increase, with influenza activity reaching epidemic levels. Andean Region: ILI activity has remained stable at low levels throughout the last four EWs. SARI cases have been stable at low levels, though there has been an increase in RSV-positive cases. Influenza activity has continued at low levels with a slightly increasing trend. The predominant influenza viruses have been type A(H3N2) with concurrent circulation of influenza A(H1N1)pdm09. RSV activity, though low, is on an upward trend, whereas SARS-CoV-2 activity continues its decline, maintaining low levels. By country: In Colombia, SARS-CoV-2 activity has decreased to low levels, influenza has remained low, and RSV has shown a slight increase. SARI activity has been around the epidemic threshold during the last four EWs, with most cases positive for RSV and influenza. Ecuador has seen a marked rise in RSV to high levels, with a decline in SARS-CoV-2 to low levels and influenza below the epidemic threshold. SARI activity is at epidemic levels, with most cases attributable to RSV. In Peru, influenza has oscillated around the epidemic threshold, with SARS-CoV-2 decreasing to low levels. Over the last four EWs, Venezuela has exhibited fluctuating influenza activity around the epidemic threshold. Brazil and the Southern Cone: Over the last four epidemiological weeks, there has been an increase in both ILI and SARI cases across the subregion, positioning at intermediate-low levels predominantly due to influenza. During this period, influenza activity has remained stable, at epidemic levels in some countries, with influenza A(H3N2) and A(H1N1)pdm09 being the predominant influenza viruses. Concurrently, RSV activity has remained low, though it has shown a slight increase. The activity of SARS-CoV-2 has continued its downward trend, maintaining low levels of circulation. By country: Argentina has seen ILI and SARI levels stay below the epidemic threshold, with influenza activity nearing this threshold and a continuing decline in SARS-CoV-2 circulation. Brazil has maintained a decline in SARS-CoV-2 activity with consistently low levels, and its influenza activity continues below the epidemic threshold. Chile has experienced a rise in both ILI and SARI cases over the period, with the cases reaching moderate levels for ILI and epidemic levels for SARI, mainly attributable to influenza circulating at moderate to high levels. In Paraguay, while SARI activity hovers around the epidemic threshold, ILI activity remains below it, with influenza showing a slight increase and exceeding the epidemic threshold; the circulation of both SARS-CoV-2 and RSV remains stable at low levels. Lastly, in Uruguay, SARI activity has fluctuated around the epidemic threshold, predominantly with cases attributable to SARS-CoV-2, whose activity is low and on a decline.