National flu and COVID-19 surveillance report: 11 December 2025 (week 50)
This report summarizes the information from surveillance systems monitoring COVID-19 (SARS-CoV-2), influenza, respiratory syncytial virus (RSV), and other seasonal respiratory viruses in England. Data is based on information up to week 49 of 2025 (1 December to 7 December 2025).
The report's release date was moved to Wednesday, 24 December 2025, due to Christmas Day falling on the next working day. Weekly reporting will resume on Thursday, 8 January 2026.
Key Findings:
Influenza Activity: Increased, circulating at medium levels. Emergency department (ED) visits for influenza-like illness (ILI) and confirmed acute respiratory infection (ARI) incidents rose. Most influenza viruses were A(H3N2).
COVID-19 Activity: Mixed trends, circulating at baseline levels. ED visits for COVID-19-like illness remained stable. SARS-CoV-2 confirmed ARI incidents in week 48 were stable.
RSV Activity: Mixed trends, circulating at medium levels. ED visits for acute bronchiolitis increased.
Other Viruses:
- Adenovirus: Stable, with a 1.8% positivity rate.
- Human Metapneumovirus (hMPV): Increasing, with a 2.5% positivity rate.
- Parainfluenza: Increasing, with a 3.5% positivity rate.
- Rhinovirus: Stable, with a 14.4% positivity rate.
Laboratory Surveillance:
- COVID-19 Cases: 705 cases in week 49, up from 626 in the previous week. PCR positivity remained stable at 2.1%.
- Influenza Cases: 21% positivity rate in week 49, up from 17%. Highest rates in those aged 5-14 (45.9%).
- RSV Positivity: 10.8% in week 49, up from 10.2%. Highest rates in those aged 0-4 (38%).
Respiratory DataMart System:
- Influenza, COVID-19, RSV, and Rhinovirus: Positivity rates increased or remained stable.
- Adenovirus, hMPV, and Parainfluenza: Positivity rates increased.
SARS-CoV-2 Lineages:
- UKHSA tracks SARS-CoV-2 lineages through genomic surveillance.
- Prevalence of designated lineages among sequenced cases is provided.
Influenza Virus Characterization:
- A(H1N1)pdm09 viruses show genetic diversity.
- A(H3N2) viruses are diverse, with most belonging to clade J.2.4.1.
- Antigenic characterisation indicates low reactivity with post-infection ferret antisera.
Genetic Characterization:
- UKHSA characterized 632 seasonal influenza viruses, identifying specific strains.
- Live attenuated influenza vaccine (LAIV) viruses detected in children.
Acute Respiratory Infection Incidents (ARI):
- Data on ARI incidents reported to UKHSA health protection teams.
- Breakdown by setting (care homes, hospitals, educational settings, prisons, other).
FluSurvey (England):
- Monitors ILI trends using self-reported symptoms from registered participants.
- Case definition includes fever, malaise, headache, muscle pain, cough, sore throat, shortness of breath.
Syndromic Surveillance:
- Collects data from healthcare sources, displaying ED visits for respiratory infections.
- Includes daily NHS 111 calls and assessments for acute respiratory infections.
Primary Care Surveillance:
- Uses a national sentinel surveillance system of GP practices.
- Data on ILI consultation rates, lower respiratory tract infections, and sentinel swabbing.
COVID-19 Hospital and ICU/HDU Admissions:
- Surveillance of COVID-19 hospitalisations and ICU/HDU admissions.
- Data from NHS trusts in England.
Influenza Hospital and ICU/HDU Admissions:
- Surveillance of influenza hospitalisations and ICU/HDU admissions.
- Data from sentinel NHS trusts in England.
RSV Hospital Admissions:
- Surveillance of RSV hospitalisations (excluding ICU/HDU).
- Data from sentinel NHS trusts in England.
ECMO Admissions:
- Surveillance of extra corporeal membrane oxygenation (ECMO) admissions.
- Data from severe respiratory failure centres in the UK.
Vaccine Coverage:
- COVID-19 vaccine uptake in England.
- Autumn 2025 campaign data, including eligible groups and vaccination rates.
- Influenza vaccine uptake in GP patients, including targeted groups and vaccination rates.
Data Sources and Methodology:
- Additional information on data sources and methodology available in the data quality report.
