Number of reported cases of RSV, flu and COVID-19 in 2024-2025; Credit: MSSS

On Wednesday 24 December 2025, the Health Directorate of Luxembourg's Ministry of Health and Social Security published its weekly overview of the evolution of major acute respiratory infections, including COVID-19, influenza (flu) and respiratory syncytial virus (RSV) for the week of Monday 15 to Sunday 21 December 2025 (week 51).

 

Slight increase in flu cases

During week 51, the number of flu cases reported by laboratories rose from 627 to 639 - an increase of almost 2% compared to the previous week. Influenza A accounted for 99% of the typed results, while influenza B represented 1%. Infections remained very common among children and adolescents.

Based on data from the last two seasons, a slowdown is observed during the school holiday period. These figures confirm, however, that the seasonal flu wave is still in its early stages. The Ministry of Health and Social Security reminded the public that vaccination is still available. This vaccination recommendation primarily concerns people aged 65 and over, who are at the highest risk of flu complications. The ministry added 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 confirmed RSV cases increased by 8% over one week, from 260 to 281. Since October 2025, 71% of infections have affected children under nine years old, indicating that the virus primarily affects younger people.

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

The number of positive COVID-19 cases decreased from 113 to 92 - down by nearly 19% compared to the previous week. Meanwhile, the viral concentration detected in wastewater has increased.

The latest available sequencing data reveals that the XFG variant (40.6%), its sub-variant XFG.3 (23.9%) and the NB.1.8.1 variant (23.9%) are predominant.

The ministry recommended the following preventative measures to limit the spread of viruses:

  • wash hands regularly with soap and water for 30 seconds, thoroughly rubbing the palms, fingers, backs of hands and under the nails;
  • cover one's mouth and nose with a tissue when coughing or sneezing - or use the crook of the elbow;
  • immediately throw used tissues in the rubbish bin and then wash one's hands;
  • avoid physical contact such as hugs, kisses and handshakes;
  • avoid crowds and gatherings during the epidemic season;
  • stay home if sick to avoid infecting others;
  • ventilate rooms regularly, at least three to four times a day for ten minutes.