Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 17 (3 May 2024)

ABSTRACT

[WEEKLY SUMMARY]. Regional Situation Over the past four epidemiological weeks (EWs), low activity levels of Influenza-Like Illness (ILI) have been noted across the Americas, exhibiting a declining trend primarily linked to North America. Simultaneously, there has been a reduction in Severe Acute Respiratory Infection (SARI) activity, which also remains low. These trends are largely associated with confirmed cases of influenza and, to a lesser extent, SARS-CoV-2. Regionally, SARS-CoV-2 activity has decreased to low levels compared to previous epidemic waves. Moreover, there has been a slight decline in seasonal influenza activity and a decrease in Respiratory Syncytial Virus (RSV) activity, both of which are currently low. North America Over the last four EWs, ILI cases have continued to decline, predominantly due to influenza, resulting in intermediate-low activity levels. Hospitalizations due to respiratory viruses have also followed a downward trend, remaining low. While influenza has maintained epidemic circulation levels, there has been a notable decrease during this period. The most common influenza viruses have been type B/Victoria, with lesser circulation of influenza A(H3N2) and A(H1N1)pdm09. RSV activity has similarly decreased, stabilizing at low levels. SARS-CoV-2 activity has also decreased, now comparable to lows from previous waves. By country Canada has seen a significant decrease in SARS-CoV-2 activity, now at low levels over the last four EWs. Influenza activity has sustained epidemic levels but has gradually decreased, and RSV activity has continued to decline, remaining low. In Mexico, influenza circulation has stayed fluctuating at epidemic levels, while SARS-CoV-2 activity has decreased to low levels. In the United States, influenza activity has decreased over the last four EWs but remains above the epidemic threshold. Both RSV and SARS-CoV-2 activities have continued their decline to low levels. ILI cases have decreased and are now at intermediate-low levels. Hospitalization rates for influenza, RSV, and SARS-CoV-2 have followed a decreasing trend, maintaining low levels. Caribbean ILI and SARI cases have maintained a downward trend over the last four weeks, primarily involving influenza and, to a lesser extent, SARS-CoV-2. Influenza activity has been low but fluctuating during the last four EWs. 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 noted in Belize, Jamaica, Guyana, and the Cayman Islands, while SARS-CoV-2 activity was observed in Barbados, Guyana, and Trinidad and Tobago. Central America During the last four EWs, both ILI and SARI activities have remained low but have shown a slight increase, with the majority of cases being positive for influenza. Influenza activity has seen a slight rise, maintaining intermediate-low levels. The predominant influenza viruses have been type A(H1N1)pdm09 and A(H3N2). Both RSV and SARS-CoV-2 activities have stayed low. By country In El Salvador, SARI activity is around epidemic levels with low SARS-CoV-2 circulation and fluctuating influenza activity around the epidemic threshold. Guatemala has witnessed stable ILI and SARI activities at epidemic levels, associated with moderate influenza circulation. Honduras has experienced fluctuating SARI activity at epidemic levels linked to influenza, whose activity is moderate. Nicaragua reports low activity levels for RSV, influenza, and SARS-CoV-2. In Panama, ILI and SARI cases have increased in the last four EWs, with influenza activity reaching epidemic levels. Andean Region ILI activity has been stable at low levels during the last four EWs. SARI cases have also been stable but low, although there has been an increase in RSV-positive cases. Influenza activity has remained low with a fluctuating trend. During this period, the predominant influenza viruses have been type A(H3N2) with concurrent circulation of A(H1N1)pdm09. RSV activity has remained low but with a growing trend. SARS-CoV-2 activity has continued to decline, maintaining low levels. By country In Colombia, SARS-CoV-2 activity has decreased to low levels, influenza activity has been low with a slight increase, and RSV, although low, has shown an increase. SARI activity has hovered around the epidemic threshold, with cases primarily due to RSV and influenza. In Ecuador, a significant rise in RSV activity to high levels has been observed, SARS-CoV-2 activity has decreased to low levels, and influenza activity has remained below the epidemic threshold. SARI activity is at epidemic levels, with most cases attributable to RSV in the last four EWs. In Peru, influenza activity has fluctuated around the epidemic threshold, and SARS-CoV-2 activity has decreased to low levels. In Venezuela, there has been fluctuating influenza activity around the epidemic threshold during the last four EWs. Brazil and the Southern Cone ILI and SARI activity has increased in the last four EWs, positioning at intermediate-low levels, predominantly due to influenza. Influenza activity has seen a rise during the last four EWs with epidemic levels in some countries. During this period, the predominant influenza viruses have been type A(H3N2) followed by A(H1N1)pdm09. RSV activity has remained low, although with a slight increase. SARS-CoV-2 activity has continued to decline, maintaining low activity levels. By country In Argentina, ILI and SARI levels have remained below the epidemic threshold, influenza activity has slightly increased, exceeding the epidemic threshold, and the positivity percentage of SARS-CoV-2 has continued to decline, reaching low levels. In Brazil, SARS-CoV-2 activity has remained in decline, with low levels, and influenza activity continues below the epidemic threshold. In Chile, both ILI and SARI cases have increased in the last four EWs, situating at moderate levels for ILI and epidemic levels for SARI; the majority of cases are attributable to influenza, circulating at high levels. In Paraguay, SARI activity is around the epidemic threshold, and ILI activity has been maintained below this threshold. Influenza activity is around the epidemic threshold; the circulation of SARS-CoV-2 and RSV remains stable at low levels. In Uruguay, SARI activity has fluctuated around the epidemic threshold, with the majority of cases attributable to SARS-CoV-2, whose activity is low and declining, while influenza activity fluctuates around the epidemic threshold.