Overview
COVID-19 is an infectious respiratory illness caused by the SARS-CoV-2 coronavirus. It ranges from no symptoms at all to severe pneumonia requiring intensive care. Most people recover at home, but some develop prolonged symptoms lasting months (Long COVID).
How common is it?
COVID-19 continues to circulate and can cause repeated waves of infection. Infection can occur more than once; the level of illness in a community changes over time.
Causes and risk factors
The SARS-CoV-2 virus spreads mainly through respiratory droplets and aerosols from an infected person's breath, coughs, or sneezes. It enters cells via the ACE2 receptor found particularly in the lungs.
Common risk factors
- Close contact with infected person
- Unventilated indoor spaces
- Advanced age
- Obesity, diabetes, heart disease, or immunosuppression
- Not being vaccinated or boosted
- Certain occupations with high public contact
Symptoms
- Fever or chills
- New continuous cough
- Loss or change in sense of smell or taste
- Fatigue
- Shortness of breath
- Headache, sore throat, runny nose
- Muscle aches and pains
- Nausea or diarrhoea
When to see a doctor
Call your local emergency number for severe or suddenly worsening breathlessness, persistent chest pain, confusion, collapse, or difficulty staying awake. Seek prompt advice if symptoms worsen, you are pregnant, or you may qualify for antiviral treatment because of a high-risk condition.
Diagnosis
Lateral flow antigen tests provide rapid home results. PCR tests are more sensitive. Blood tests, chest X-ray, and CT scans are used for hospitalised patients to assess severity.
Treatments
Supportive care at home
Rest and maintain fluids as appropriate for your health. Paracetamol or ibuprofen may help fever or pain if suitable; ask a pharmacist about kidney disease, pregnancy, stomach ulcers or medicine interactions. Many people recover over a few weeks, but some have symptoms for longer.
Antiviral medication
Some people at highest risk of severe illness are eligible for antiviral treatment. Contact the relevant clinical service promptly when symptoms start or a test is positive; treatment has a short starting window. Eligibility, timing, kidney function and interactions must be checked for the specific medicine.
Hospital care for severe illness
Supplemental oxygen, dexamethasone, and other supportive measures. Intensive care with mechanical ventilation for the most severe respiratory failure.
Self-care and lifestyle
- Vaccination and boosters remain the most effective protection against severe disease
- Ventilate indoor spaces and use face coverings in crowded settings when transmission is high
- Long COVID symptoms should be discussed with a doctor for appropriate referral and support
- Pacing activity is important in Long COVID to avoid worsening fatigue
Prevention
Vaccination significantly reduces the risk of severe illness, hospitalisation, and death. Good ventilation, hand hygiene, and staying home when symptomatic reduce transmission.
Sources for targeted updates
Updated: 24 October 2026. Targeted corrections to frequency, treatment, urgent-care guidance, key facts. This update covers the named sections; a full review of the remaining guide is pending.