Overview
COVID-19 is an infectious disease caused by the SARS-CoV-2 coronavirus, first identified in Wuhan, China in December 2019. It spread rapidly to become a global pandemic. Most people with COVID-19 experience mild to moderate respiratory illness and recover without special treatment. However, some develop severe disease requiring hospitalisation, particularly older adults and those with underlying health conditions. Vaccination significantly reduces the risk of severe illness.
Causes and risk factors
The following factors are associated with the development of COVID-19:
- Infection with SARS-CoV-2 coronavirus
- Spread through respiratory droplets and aerosols from infected people
- Less commonly through contaminated surfaces
- Close contact with infected person
- Poorly ventilated indoor spaces
- Higher risk in older adults and those with underlying conditions
Signs and symptoms
Common signs and symptoms of COVID-19 include:
- Fever or chills
- Dry cough
- Fatigue
- Shortness of breath or difficulty breathing
- Muscle aches
- Headache
- Loss of taste or smell
- Sore throat
- Runny nose
- Nausea or vomiting
- Diarrhoea
- Rash in some cases
- In severe cases: pneumonia and respiratory failure
Diagnosis
COVID-19 is typically diagnosed through a combination of medical history, physical examination, and appropriate investigations such as blood tests, imaging, or specialist review, depending on the specific condition and presentation. Your doctor will consider all relevant symptoms and risk factors before making a diagnosis.
Treatment options
Treatment approaches for COVID-19 may include:
- Rest and fluid intake for mild cases
- Antipyretics (paracetamol) for fever
- Oxygen therapy for hospitalised patients
- Antiviral medications: nirmatrelvir/ritonavir (Paxlovid), remdesivir for high-risk
- Dexamethasone for severe cases requiring oxygen
- Anti-inflammatory medications
- ICU support for critical cases
- COVID-19 vaccination for prevention
Prevention
COVID-19 vaccination, wearing masks in high-risk settings, good ventilation, hand hygiene, staying home when unwell, and staying up to date with boosters.
Complications
If left untreated or poorly managed, COVID-19 can lead to complications including:
Long COVID (persistent symptoms for months), lung damage, cardiovascular complications, neurological effects, blood clots, and death.
Sources and references: This article is written in accordance with NHS UK, WHO, and Mayo Clinic clinical guidelines. It is reviewed for accuracy by the SymptomSense content team. ICD-10 code: U07.1. Last reviewed June 2026.