RSV activity in Belgium
Current respiratory syncytial virus (RSV) activity in Belgium — based on ECDC ERVISS weekly data from Sciensano.
Current situation: RSV
In week 15 of 2026, activity of respiratory syncytial virus (RSV) in Belgium is low. The trend — derived from clinical surveillance — is falling.
The classification is based on the ECDC ERVISS weekly reports, drawing on RSV surveillance data from Sciensano via its sentinel GP network and the National Reference Centre for Influenza. Seasonally, infection waves in Belgium typically peak between December and February; activity is usually markedly lower in spring and summer. How severe a given season becomes depends on the circulating virus variant and the population's immune status, among other factors.
Data sources and methodology
The current picture for Belgium is built on the European Respiratory Virus Surveillance Summary (ERVISS), published weekly by the European Centre for Disease Prevention and Control (ECDC). Sciensano via its sentinel GP network and the National Reference Centre for Influenza is the national public-health authority that feeds ERVISS with sentinel primary care and virology data.
ECDC ERVISS
ERVISS is ECDC's weekly pan-European surveillance summary for influenza, SARS-CoV-2 and RSV. National authorities — in Belgium's case Sciensano via its sentinel GP network and the National Reference Centre for Influenza — submit harmonised indicators every week, which ECDC publishes in a standardised dataset on Thursdays. Using ERVISS rather than each country's native portal ensures cross-country comparability.
ILI / ARI consultation rates and positivity
Sciensano via its sentinel GP network and the National Reference Centre for Influenza operates a sentinel network of general practices that report weekly rates of patients consulting for influenza-like illness (ILI) or acute respiratory infection (ARI). A subset of patients is swabbed and tested by reference laboratories, producing pathogen-specific positivity rates for flu, SARS-CoV-2 and RSV.
Why this source
Combining consultation incidence with virological positivity yields a pathogen-specific weekly incidence signal (ILI × positivity / 100). This is the standard European methodology and provides a more robust view than either indicator alone — consultation rates capture illness burden, positivity confirms which pathogen is driving it.
Qualitative classification
The “low”, “moderate” and “high” categories follow seasonal reference values and epidemiological thresholds calibrated to match our classifications for other countries. The ILI × positivity / 100 product is scaled to comparable thresholds using a divisor of 3, which aligns European sentinel peaks with the consultation-equivalent scale used elsewhere. Data refreshes weekly when ECDC publishes the latest ERVISS update, typically on Thursdays.
Frequently asked questions
When is RSV season in Belgium?
RSV in Belgium typically returns in late autumn, rises through November and December, and peaks between December and February before fading in spring. Sciensano tracks RSV activity within its weekly respiratory-virus surveillance, and post-pandemic seasons have been somewhat less predictable than pre-2020 patterns, with earlier onset in some years.
Who is most at risk from RSV in Belgium?
The groups at highest risk of severe RSV are infants — especially those under six months, preterm babies, and children with underlying heart or lung disease — and older adults, particularly those aged 75 and above or with chronic respiratory or cardiac disease. In otherwise healthy children and adults, RSV usually resembles a common cold and resolves without complications.
Are RSV vaccines available in Belgium?
Since 2023, the EU has authorised RSV vaccines for older adults and the long-acting monoclonal antibody nirsevimab for infants. Belgium has progressively introduced nirsevimab for infants entering their first RSV season and RSV vaccination for older adults in defined risk groups, guided by recommendations from the Conseil Supérieur de la Santé / Hoge Gezondheidsraad. Sciensano monitors uptake and paediatric hospitalisation trends.
How is RSV surveillance organised in Belgium?
Belgian RSV surveillance combines sentinel-laboratory testing, sentinel GP data, and hospital-admission signals coordinated by Sciensano. Results feed Sciensano's weekly respiratory-virus bulletin and ECDC ERVISS, which makes Belgium's RSV curve directly comparable with neighbours such as the Netherlands, France, and Luxembourg.
How does RSV differ from flu in Belgian data?
In Sciensano's respiratory panel, flu and RSV appear as distinct positivity streams. RSV disproportionately affects infants and the very elderly and is the main cause of bronchiolitis hospitalisations, while flu burden is spread across age bands and is especially severe in older adults. Symptom overlap is wide, so the distinction is drawn from laboratory testing rather than clinical impression.
Want the actual numbers?
You'll find them in the app.
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