RSV activity in Sweden
Current respiratory syncytial virus (RSV) activity in Sweden — based on ECDC ERVISS weekly data, set against the parallel flu and COVID-19 trajectories.
Current situation: RSV
In week 15 of 2026, activity of respiratory syncytial virus (RSV) in Sweden is low. The trend — derived from clinical surveillance — is stable. Over a four-week comparison, a clear decline is visible.
The classification is based on the ECDC ERVISS weekly reports, drawing on RSV indicators from the Public Health Agency of Sweden (Folkhälsomyndigheten); where national indicators are stale, the EU median is used as a fallback. Seasonally, infection waves in Sweden 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 Sweden is built on the European Respiratory Virus Surveillance Summary (ERVISS), published weekly by the European Centre for Disease Prevention and Control (ECDC). Folkhälsomyndigheten is the national public-health authority that feeds ERVISS with sentinel primary care and virology data. Sweden does not always report ILI consultation rates to ERVISS; when national ILI is missing we fall back to the EU median so the signal remains comparable.
ECDC ERVISS
ERVISS is ECDC's weekly pan-European surveillance summary for influenza, SARS-CoV-2 and RSV. National authorities — in Sweden's case Folkhälsomyndigheten — 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
Folkhälsomyndigheten 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 Sweden?
Sweden's RSV season typically runs from late autumn through early spring, with peaks most often between January and March. The season's intensity and exact timing vary year to year, and post-pandemic seasons have been less predictable than pre-2020 ones. Folkhälsomyndigheten publishes weekly RSV updates alongside flu and SARS-CoV-2.
How is RSV tracked in Sweden?
RSV surveillance in Sweden relies on mandatory laboratory reporting via the Svebar network, supplemented by sentinel physician reports and regional hospital data. Folkhälsomyndigheten publishes weekly RSV activity tiers and contributes the data to ECDC's ERVISS, which places Sweden's RSV trajectory next to the rest of the EU/EEA.
Who is most at risk from RSV in Sweden?
The groups most affected are infants under six months, preterm babies, and adults aged 60 and older, particularly those with underlying heart or lung disease. In these groups RSV can cause severe bronchiolitis or pneumonia. Swedish clinical practice has adopted both infant prophylactic antibodies and adult RSV vaccination for qualifying risk groups, consistent with broader European guidance.
How does Sweden compare to other European countries?
Because Sweden reports into ERVISS with the same tiering as the rest of the EU/EEA, its RSV curve can be compared directly with neighbours. Nordic RSV peaks often cluster within a few weeks of each other, slightly later than central European peaks. This makes ECDC's side-by-side dashboard useful for anticipating paediatric pressure across borders.
How does RSV differ from flu in Swedish data?
In Swedish surveillance, flu and RSV appear as separate positivity streams within the same respiratory panel. RSV disproportionately hits infants and the very elderly, while flu burden spreads across age bands. Symptom overlap between the two viruses is wide, so the distinction is drawn from laboratory testing rather than clinical impression.
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