Regional Update, Influenza and Other Respiratory Viruses. Epidemiological Week 5 (9 February 2024)

ABSTRACT

[WEEKLY SUMMARY]. Regional Situation Over the past four Epidemiological Weeks (EWs), there has been a decline in the activity of Influenza-Like Illness (ILI) in the Americas region, stabilizing at medium levels. Similarly, a decrease has been observed in the activity of Severe Acute Respiratory Infection (SARI), 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 mainly linked to moderate activity observed in North America and the Caribbean, which is currently declining, while SARI activity has been particularly influenced by activity in North America. Regarding the circulation of respiratory viruses, a moderate activity of SARS-CoV-2 has been maintained at the regional level compared to previous epidemic waves. Likewise, an epidemic activity of influenza has been observed for this time of year with a decreasing trend, and a moderate activity of Respiratory Syncytial Virus (RSV) has shown a decline. North America ILI cases, after a slight decrease in previous EWs, have remained at medium-high levels, with the majority of cases attributable to influenza, although showing a decline in this proportion. SARI cases have decreased, with the majority of cases attributable to influenza and, to a lesser extent, SARS-CoV-2. Influenza activity has remained at epidemic levels after a slight decrease in previous EWs. During this period, the predominant influenza viruses have been type A(H1N1)pdm09, with concurrent circulation of influenza B/Victoria and, to a lesser extent, influenza A(H3N2). RSV activity has shown a decline in the last four EWs, remaining at moderate levels. SARS-CoV-2 activity has decreased in the last four EWs to low levels. By countries In Canada, SARS-CoV-2 activity has markedly decreased in the last four EWs to medium levels. Influenza activity remains at epidemic levels, and RSV activity has remained stable at high levels during this period. In Mexico, influenza circulation has remained fluctuating at epidemic levels in the last four EWs, while an increase in SARS-CoV-2 circulation has been observed. In the United States, influenza activity has remained above the epidemic threshold with a slight increase in the last two EWs, RSV activity has decreased to moderate levels, and although SARS-CoV-2 has remained at high levels, it has shown a decreasing trend. Hospitalization rates for influenza, RSV, and SARS-CoV-2, after reaching similar high levels to the previous season, have shown a downward trend in the last four EWs. Caribbean ILI cases have shown an increase in the last four weeks associated with an increase in positive influenza cases, while SARI cases have remained on the decline. Influenza activity has decreased in the last four EWs, reaching low circulation levels. During the last four EWs, the predominant viruses have been type A(H1N1)pdm09, followed by A(H3N2) and, to a lesser extent, B/Victoria. RSV activity has remained at low levels. SARS-CoV-2 activity has remained at high levels, although showing a decreasing trend. By countries Elevated influenza activity has been observed in Jamaica. Elevated SARS-CoV-2 activity has been observed in Belize, Dominican Republic, Dominica, Jamaica, Barbados, the Cayman Islands, and Guyana. Central America After an increase observed in previous weeks, ILI cases have shown a decrease in the last four weeks, with the majority of positive cases attributable to SARS-CoV-2 and, to a lesser extent, influenza. SARI cases have also shown a decrease, reaching low levels. Influenza activity, after the increase observed in previous weeks, has shown a decrease in the last two EWs, reaching medium levels. During this period, the predominant viruses have been type A(H1N1)pdm09, followed by B/Victoria and, to a lesser extent, A(H3N2). RSV activity has shown a decrease to low levels. SARS-CoV-2 activity, although remaining at low levels, has increased in the last four EWs. By countries In El Salvador, SARS-CoV-2 activity has shown a marked increase in the last four EWs to high 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 on the decline at epidemic levels. In Honduras, after the increase in ILI and SARI cases associated with positive influenza and SARS-CoV-2 cases observed in previous weeks, a decrease has been detected in the last two EWs, reaching levels below the epidemic threshold. In Nicaragua, RSV activity has shown a decrease to low levels in the last four weeks, and both influenza and SARS-CoV-2 levels have remained low. In Panama, SARS-CoV-2 activity, after reaching high levels, has shown a decrease, and influenza activity has fluctuated around the epidemic threshold in the last four EWs. ILI and SARI cases, after the increase observed in previous EWs, have shown a decrease in the last four EWs, with the majority of positive cases attributable to SARS-CoV-2. Andean ILI activity has remained stable at low levels, and SARI cases, after an increase, have shown a decrease with the highest proportion of positive cases attributable to SARS-CoV-2. Influenza activity has remained at low levels in the last four EWs. During this period, the predominant influenza viruses have been type A(H1N1)pdm09, with circulation of B/Victoria and A(H3N2) to a lesser extent. RSV activity has remained at low levels. SARS-CoV-2 activity has remained at high levels and increasing. By countries In Bolivia, SARS-CoV-2 circulation has remained high. In Colombia, SARS-CoV-2 activity has shown a pronounced increase in the last four EWs, reaching high levels; SARI cases, after the recent increase associated with positive influenza and SARSCoV- 2 cases, have experienced a decrease in the last two EWs. In Ecuador, SARS-CoV-2 has shown a decrease in activity, reaching medium-low levels; influenza activity has continued to decline around epidemic thresholds, and RSV activity has shown a slight increase in the last four EWs. Following the recent increase in SARI cases associated with positive influenza, SARS-CoV-2, and to a lesser extent RSV cases, a decrease has been observed in the last four EWs, remaining at epidemic levels. In Venezuela, a fluctuating influenza activity below the epidemic threshold has been observed in the last four EWs. Brazil and the Southern Cone SARI and ILI activity has remained low in the last four EWs, with the majority of positive cases attributable to SARS-CoV-2, with a percentage of positive cases increasing. Influenza activity has remained at low circulation levels during the last four EWs. During this period, the predominant influenza viruses have been type 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 rise at high levels. By countries In Argentina, ILI and SARI levels have remained below the epidemic threshold. However, an increase in the positivity rate of SARS-CoV-2 has been observed, reaching high levels in the last four EWs. In Brazil, SARS-CoV-2 activity has remained stable at high levels. In Chile, after a marked decrease, SARS-CoV-2 activity has recently increased again in the last four EWs, with ILI cases at epidemic levels and SARI cases below this threshold, mostly attributable to SARS-CoV-2 and, to a lesser extent, influenza, whose activity has exceeded the epidemic threshold. In Paraguay, SARS-CoV-2 circulation has shown a decrease in the last two EWs, reaching moderate levels, and influenza activity has decreased to levels below the epidemic threshold, while SARI activity has remained at epidemic levels with the majority of positive cases attributable to SARS-CoV-2. In Uruguay, SARI activity has continued at levels below the epidemic threshold, with the majority of the few positive cases attributable to SARS-CoV-2.