Luxembourg flu outbreak, rise in RSV and COVID-19

With the onset of winter, Luxembourg is under increasing pressure from three major respiratory viruses: influenza, respiratory syncytial virus (RSV) and coronavirus. According to the weekly report of the Directorate of Health, the country entered the phase of an active seasonal influenza epidemic from 1 to 7 December 2025.

The number of laboratory-confirmed flu cases doubled during the week, from 182 to 367. The prevalence is particularly high among children and adolescents. Of all typed samples, 99.7 per cent were influenza A virus, while the share of B virus was almost zero - only 0.3 per cent. This is a typical ratio for the beginning of an epidemic, but such growth rates indicate a particularly aggressive start to the season.

Against this background, the Ministry of Health and Social Protection reminds that vaccination remains the most reliable way to protect against influenza and its complications. This year, vaccination became free of charge for all citizens under 18 years of age, a measure directly aimed at combating high morbidity among young people.

At the same time, RSV circulation is also increasing. During the week, 161 cases were confirmed - 59% more than the week before. Since October 2025, 73% of all those infected have been children under nine years of age. This figure confirms that the virus is actively spreading among the most vulnerable groups and requires increased attention from the paediatric service and parents.

COVID-19 is again showing signs of growth. The number of new positive tests increased by 78%, from 51 to 91 cases. However, despite the increase in reported diagnoses, the level of viral load in wastewater continues to decline, according to sanitary surveillance data. This may indicate localised outbreaks that do not reflect mass spread of infection.

In terms of strains, the predominant variants are XFG (54.2%) and its sub-variant XFG.3 (29.1%), both belonging to a new wave of SARS-CoV-2 mutations about which little is known, but which do not yet appear to be leading to severe disease on a mass scale.