COVID-19
SARS-CoV-2 infection ranging from mild respiratory illness to severe pneumonia.
Overview
COVID-19 is caused by the SARS-CoV-2 virus. Most cases are mild but high-risk groups can develop severe disease, blood clots and long COVID.
Symptoms
- • Cough
- • Fever
- • Sore throat
- • Loss of smell or taste
- • Fatigue
- • Breathlessness
Risk factors
- • Older age
- • Obesity
- • Diabetes
- • Heart or lung disease
- • Immunosuppression
- • Unvaccinated status
Causes
- • SARS-CoV-2 virus, airborne droplet and aerosol spread
🚨 Red flags — seek urgent care
- • Oxygen saturation <94%
- • Severe breathlessness
- • Confusion
- • Chest pain
- • Bluish lips
When to seek care
- • High-risk patient with positive test
- • Symptoms worsening after day 5–7
- • Persistent fever beyond 5 days
Diagnosis
- • Clinical features: fever, cough, anosmia, sore throat, fatigue, breathlessness
- • Lateral flow antigen test or PCR confirmation
- • Risk stratify: pulse oximetry (silent hypoxia), age, comorbidities, vaccination status
Treatment
- • Most cases: rest, fluids, paracetamol, isolation per current public-health advice
- • Antivirals (nirmatrelvir/ritonavir, molnupiravir, remdesivir) for high-risk outpatients within 5 days of onset
- • Hospital: oxygen for SpO2 <94%, dexamethasone if on oxygen, anticoagulation, IL-6 inhibitors in selected cases
- • Address long-COVID with multidisciplinary rehab
Prevention
- • Vaccination per current schedule (primary + boosters)
- • Hand hygiene and well-ventilated indoor spaces
- • Masks in high-risk settings during community surges
- • Stay home and test when symptomatic
Complications
- • Hypoxaemic respiratory failure and ARDS
- • Venous thromboembolism, stroke, myocarditis
- • Acute kidney injury and multi-organ dysfunction
- • Post-COVID condition (long COVID): fatigue, breathlessness, cognitive symptoms
- • Secondary bacterial infection
Education & self-care
Vaccination, ventilation and early testing remain the most effective strategies. Pulse oximetry at home is a useful early warning tool.
Frequently asked questions
When am I no longer infectious?
Most people are no longer infectious 5–10 days after symptom onset, sooner if afebrile.
Do I need antivirals?
Eligible high-risk patients benefit from antivirals if started within 5 days of symptom onset.
When can I stop isolating?
Current UK advice is to stay home and avoid contact with vulnerable people for 5 days after a positive test or symptom onset, longer if still feverish. Specific occupational guidance may differ.
Are antivirals like Paxlovid for everyone?
No — they are reserved for people at higher risk of severe disease (older age, immunosuppression, certain chronic conditions) and must be started within 5 days of symptoms to be effective.
What is long COVID?
Persistent symptoms — fatigue, breathlessness, brain fog, palpitations — lasting beyond 12 weeks and not explained by another diagnosis. Multidisciplinary rehabilitation gives the best results.