Influenza could spoil New Year's Eve celebrations

On the eve of the Christmas holidays, the Luxembourg Directorate of Health published a weekly retrospective showing that the incidence of the main respiratory infections, with the exception of COVID-19, is on the rise in the country. The main feature of the week from 15 to 21 December 2025 was a moderate but steady increase in the number of infections with influenza and RSV, a virus that is particularly dangerous for young children.

Compared to the previous week, the number of laboratory-confirmed influenza cases rose from 627 to 639, an increase of 2%. Although the figure seems insignificant, the dynamics indicate the development of a seasonal epidemic. The vast majority of samples - 99 per cent - are from the influenza A virus, which is known for its more severe course and rapid transmission. Influenza B is almost non-existent (1%).

According to the Ministry of Health, the infection is particularly active among children and adolescents - the school season serves as a natural catalyst for the epidemic. However, it is historically known that during the Christmas holidays, the spread temporarily slows down. Despite this, the flu wave is now in its active phase. Vaccination is still available and is especially recommended for people over 65 years of age - the main risk group for complications.

In parallel with flu, the number of RSV (respiratory syncytial virus) infections is also on the rise - an increase of 8% over the week, from 260 to 281 cases. Since the start of autumn 2025, 71% of all those infected have been children under nine years old. RSV is dangerous because it can cause bronchiolitis and pneumonia in the very young, often leading to hospitalisations. According to past data, paediatric wards in the country tend to experience the highest load in December and January.

COVID-19 showed a decline against the background of an increase in other infections: 92 cases were registered during the week - 19% less than previously. However, contrary to the decline in clinical data, the concentration of SARS-CoV-2 virus in wastewater has increased. This may indicate latent circulation of the virus in the population, especially if people are asymptomatic.

Genomic monitoring revealed the dominance of the XFG variant (40.6%), its sub-variant XFG.3 (23.9%) and strain NB.1.8.1 (also 23.9%). All three belong to a new generation of Omicron subtypes, which are highly infectious but have not yet shown increased pathogenicity.