Coronavirus COVID-19

Key disease facts

COVID-19 is a disease caused by a new type of coronavirus, the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). This virus was first detected in Wuhan, China, in December 2019 and has led to a pandemic, declared by the World Health Organization on 11th March 2020.

This page provides the following information:

  • Key facts about COVID-19
  • What is a coronavirus?
  • How can you protect yourself?

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was first detected in the city of Wuhan, China, in December 2019, after a cluster of patients with pneumonia of unknown cause were reported to the World Health Organization (WHO). The outbreak was declared a public health emergency of international concern on 30thJanuary 2020, and the disease caused by SARS-CoV-2 was officially named COVID-19 on 11thFebruary 2020. After assessing the outbreak and following transmission of the virus in many other countries worldwide, on 11thMarch 2020 the WHO declared COVID-19 a pandemic. This means that the disease has spread worldwide, and it is the first time that a coronavirus has been known to have led to a pandemic. 

What are the symptoms?

COVID-19 can cause a range of symptoms of varying severity. Some people with COVID-19 will not experience any symptoms, and this is called asymptomatic infection. For around 40% of people who contract COVID-19, symptoms are mild and without hypoxia (a low level of oxygen in the blood) or pneumonia:

Main symptoms (most people have at least one of these):

  • A high temperature 
  • A new, continuous cough
  • A loss or change to your sense of smell or taste

Other symptoms:

  • Shortness of breath
  • Fatigue
  • Loss of appetite
  • Muscle ache
  • Sore throat
  • Headache
  • Nasal congestion
  • Diarrhoea, nausea and vomiting

Atypical symptoms can occur in older and immunocompromised people, often in the absence of a fever:

  • delirium
  • reduced mobility


About 40% of people with COVID-19 have moderate symptoms and non-severe pneumonia, 15% have significant disease including severe pneumonia, and 5% experience critical disease with life-threatening complications. Critical disease includes acute respiratory distress syndrome (ARDS), sepsis, septic shock, cardiac disease, thromboembolic events, such as pulmonary embolism and multi-organ failure.

SARS-CoV-2 is mainly spread via respiratory droplets through coughing and sneezing, but it has been detected in blood, faeces and urine.

Infants and children generally appear to experience milder symptoms than adults and further evidence is needed about the association between underlying conditions and risk of COVID-19 disease in children. A rare presentation of multisystem inflammatory syndrome temporarily associated with COVID-19 in children and adolescents has been noted.

There is growing evidence that in those who develop critical COVID-19 disease, there can be longer-term consequences such as rare neurological and psychiatric complications. These may include stroke, delirium, anxiety, depression, damage or inflammation of the brain, and sleep disturbances. Refer to the long-term health effects guidance for further information on commonly reported symptoms and services available for recovering COVID-19 patients.

Some factors are associated with a higher chance of developing severe or critical COVID-19 disease. These are:


You can help to prevent the spread of COVID-19 by following the NHS guidance to protect yourself and others:

  • Wash your hands regularly for at least 20 seconds using soap and water, or use hand sanitiser if you cannot access facilities.
  • Wear a face covering in public spaces, especially indoors.
  • Try to stay two metres away from others where possible.

The control of a respiratory disease like COVID-19 is dependent on everyone in the country taking preventative measures to protect themselves and each other. If you feel unwell, with any of the symptoms above, you should follow the NHS guidance.

How is it passed on?

Coronaviruses are a group of viruses that infect animals or humans. Animal coronaviruses mostly don’t infect humans, but can sometimes be transmitted from animals to humans. Most human coronaviruses cause a mild illness, such as the common cold, but there have been recent outbreaks by new coronaviruses that can cause more severe diseases, like middle east respiratory syndrome (MERS), and severe acute respiratory syndrome (SARS). So far, scientists have not been able to identify the animal which led to human infection with the 2019 coronavirus but there are reports that the genome of SARS-CoV-2 is most similar to that of bat coronaviruses. 

There are still many uncertainties around the COVID-19 pandemic, but scientists are using all the data available to identify the epidemiology of the disease. The World Health Organisation are monitoring global cases and deaths from COVID-19. You can see an overview of the global situation, including the number of cases, hospitalisations and deaths from COVID-19 on Our World in Data, a University of Oxford research project. For information about the UK, including specific areas and the number of patients in hospital, see UK Summary. Detailed surveillance information is also available from the UK four nations health departments:

COVID-19 has been compared with seasonal influenza, and while both may cause similar symptoms, the European Centre for Disease Control estimates that 1 in 1000 people die prematurely when infected with influenza, and the current estimates for COVID-19 suggest that 10 people in every 1000 infected will die from the disease in high-income countries. See the ECDC website for more information.

What protection is available?

The practical measures being introduced and the local and national guidance is changing rapidly. To stay up to date, visit this UK government website. People are being advised to stay at home if they experience any of the common COVID-19 symptoms, to restrict unnecessary travel to some countries, and to increase respiratory hygiene practices like hand washing and binning tissues. 

All government advice is based on the most up-to-date scientific information, and our researchers, politicians, doctors and nurses are working hard to protect the UK from the most severe public health crisis in a generation. But they need the support of everyone else across the country to fight this epidemic. We must all work together to protect ourselves and each other from this disease. 

In December 2020, the UK began a COVID-19 vaccination programme. This is currently focused on protecting those most at-risk of developing severe COVID-19 disease. See COVID-19 vaccines for more information about this.

Page last updated: 
Monday, February 8, 2021