COVID-19, RSV Cases Increase, Flu Cases Double in Luxembourg

On Thursday 11 December 2025, the Health Directorate of Luxembourg's Ministry of Health and Social Security published its weekly overview on the development of major acute respiratory infections, including COVID-19, influenza (flu) and respiratory syncytial virus (RSV), for the week of Monday 1 to Sunday 7 December 2025 (week 49).

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

During week 49, the number of positive COVID-19 cases increased from 51 to 91, representing a 78% increase compared to the previous week. On the other hand, the viral concentration detected in wastewater declined. The latest available sequencing data reveal that the XFG variant (54.2%) and its sub-variant XFG.3 (29.1%) remained predominant.

Flu cases double

The number of flu cases reported by laboratories doubled, rising from 182 to 367 cases (+102%), over one week. Influenza A accounted for 99.7% of the typed results and influenza B for 0.3%.

The Ministry of Health and Social Security noted that these figures confirm the start of the seasonal flu wave and recalled that vaccination is still available - and is free, starting this year, for children and adolescents under the age of eighteen. The ministry noted that vaccination remains the most reliable way to prevent seasonal flu and reduce the risk of related complications.

Increase in RSV cases

The number of RSV cases reported by laboratories saw a 59% increase, with 161 confirmed cases compared to 101 the previous week. Since October 2025, 73% of infections have occurred in children under the age of nine, indicating that the virus mainly affects younger age groups.

EO