Number of reported cases of RSV, COVID-19 and flu during week 52 of 2025; Credit: MSAN

On Friday 2 January 2026, the Health Directorate of Luxembourg’s Ministry of Health and Social Security published its weekly overview on the evolution of major acute respiratory infections, including COVID-19 / SARS-CoV-2, influenza (flu) and respiratory syncytial virus (RSV), covering the period from Monday 22 to Sunday 28 December 2025 (week 52).

Decrease in COVID-19 / SARS-CoV-2 cases

During week 52, the number of positive SARS-CoV-2 cases decreased from 92 to 70, representing a 24% drop compared to the previous week. However, the viral concentration detected in wastewater increased. The latest available sequencing data show that the XFG variant (40.6%), its subvariant XFG.3 (23.9%) and the NB.1.8.1 variant (23.9%) were predominant.

Decrease in flu cases, circulation remains high

The number of influenza cases reported by laboratories fell from 640 to 544 over one week, representing a 15% decrease. Influenza A accounted for 99.6% of typed results, while influenza B represented 0.4%. Although a seasonal decline in reported cases is typically observed during the school holiday period, the circulation of seasonal influenza remains high. The ministry noted that vaccination remains possible and is particularly recommended for people aged 65 and over, who are most at risk of complications.

Significant decrease in RSV cases

RSV cases declined sharply during week 52, with 149 confirmed cases reported, compared to 285 the previous week, representing a decrease of 48%. Since October 2025, around 70% of RSV infections have affected children under the age of ten, indicating that the virus continues to predominantly impact younger age groups.