COVID-19

Overview

COVID-19 is an infection caused by a virus that spreads through the air when an infected person breathes, talks, coughs or sneezes. The NHS says its symptoms are very similar to those of other illnesses such as colds and flu. Some people, including older adults, those with weakened immune systems and those with certain long-term conditions, are at higher risk of severe illness, according to WHO. Some people go on to have symptoms that last for a long time, which is called long COVID.

Symptoms

What a clinician may find

• A high temperature
• Difficulty breathing or shortness of breath in more severe illness, which the CDC lists as an emergency warning sign in adults

Complications

• Becoming seriously ill, especially in people at higher risk
• Pneumonia and sepsis in some people admitted to hospital, as recorded in a US hospital study published by the CDC
• Long COVID, with symptoms lasting for weeks or longer
• Persistent tiredness, breathlessness, joint pain and aching muscles after the infection
• Problems with memory and concentration, often called brain fog
• Heart palpitations, dizziness, and anxiety or depression during long COVID

Diagnosis

The NHS says the symptoms are very similar to those of colds and flu. It also says most people cannot get free rapid lateral flow tests, though some people at highest risk of serious illness can, and that most people with symptoms do not need to take one. For people eligible for COVID-19 treatments, the NHS advises taking a rapid lateral flow test as soon as symptoms start.

Treatment

The NHS says home measures such as rest, plenty of fluids and paracetamol or ibuprofen can ease symptoms. For a cough, it suggests avoiding lying flat on the back and not using a fan to cool the room. The NHS offers antiviral medicines, including nirmatrelvir with ritonavir and molnupiravir, to people at highest risk of becoming seriously ill. The CDC says antiviral treatment has to be started soon after symptoms begin.

Prevention

Vaccination helps protect against severe illness, and the UK offers a seasonal programme to the groups at highest risk of serious illness. The NHS advises staying at home and away from others when there is a high temperature or a person does not feel well enough to do normal activities.

Key facts

What is COVID-19 and how does it spread?

COVID-19 is an illness caused by a virus called coronavirus, formally SARS-CoV-2. WHO says the virus spreads through the air in infectious respiratory particles that an infected person releases when breathing, talking, coughing or sneezing. It can also spread when someone touches a contaminated surface and then touches the eyes, nose or mouth.

People are more likely to catch the virus when they are close to an infected person, or when they share a closed space with them. The US Centers for Disease Control and Prevention (CDC) says that anyone infected can spread the virus even without symptoms, and that people can pass it on before symptoms begin. A CDC travel guide adds that most spread seems to happen early in the infection, particularly in the day or two before symptoms start.

What are the symptoms of COVID-19?

The NHS says the symptoms are very similar to those of other illnesses such as colds and flu, which can make them hard to tell apart. The most typical ones are a high temperature, a new continuous cough, and a change in the sense of smell or taste. The NHS also lists shortness of breath, tiredness, body aches and headache, and some people have a sore throat or diarrhoea. It says most people feel better within a few weeks, although recovery can take longer.

The NHS advises staying at home and away from other people when there is a high temperature or a person does not feel well enough to do normal activities. Normal activities can restart once the person feels better or the temperature has gone down. Self-care described by the NHS includes resting, drinking plenty of fluids and considering paracetamol or ibuprofen. For a cough, it suggests avoiding lying flat on the back and not using a fan to cool the room.

Who is at higher risk of becoming seriously ill?

WHO says older adults, people with underlying health conditions and unvaccinated people are at higher risk of severe illness. The conditions it lists include high blood pressure, diabetes, obesity, chronic lung, heart, liver and kidney diseases, cancer and dementia. Pregnant women and people with immunosuppression, such as those taking immunosuppressive medicines or living with HIV, are also named as higher-risk groups.

The CDC says the risk of severe illness is greater as the number of underlying conditions increases, and that age is the strongest risk factor. In a US hospital study published by the CDC, pneumonia was the most common respiratory complication among people admitted with COVID-19, and sepsis was also recorded. The NHS offers antiviral medicines to people at highest risk of becoming seriously ill.

How is COVID-19 tested and treated?

The NHS says most people cannot get free COVID-19 rapid lateral flow tests, though some people at highest risk of serious illness can. Its symptoms page says most people with symptoms do not need to take a rapid lateral flow test. People who are eligible for COVID-19 treatments are advised to take one as soon as symptoms start.

The NHS says home measures such as rest and plenty of fluids can ease symptoms. Antiviral medicines, such as nirmatrelvir with ritonavir (Paxlovid) and molnupiravir (Lagevrio), are offered by the NHS to people at highest risk of becoming seriously ill, and a doctor advises which treatment is most suitable after assessment. The CDC says antiviral treatment has to be started soon after symptoms begin, and advises people at higher risk to talk to a healthcare provider right away, even with mild symptoms. Testing can also help guide treatment decisions, according to the CDC.

How does the vaccination programme work?

The UK runs a seasonal COVID-19 vaccination programme for the groups at highest risk of serious illness. The NHS says the vaccine is available to people aged 75 and over, to people aged 6 months to 74 with a weakened immune system, and to residents of care homes for older adults. For the spring 2026 programme, UKHSA said the groups were the same across England, Scotland, Wales and Northern Ireland. Eligibility for people with a weakened immune system depends on criteria in the Green Book.

The NHS gives examples such as blood cancer, organ, bone marrow or stem cell transplants, HIV and some long-term steroid treatment, and notes that the list does not cover everything. Some people with a severely weakened immune system may need an extra dose. Eligible people can book online or in the NHS App, or go to a walk-in site, without waiting for an invitation. Eligibility has changed between seasons: for autumn and winter 2025/26 it was narrowed to people at highest risk of serious illness.

What is long COVID and when should someone get help?

The NHS describes long COVID, also called post-COVID syndrome, as symptoms of COVID-19 that last longer than 12 weeks. The most common symptoms include extreme tiredness, shortness of breath, joint pain and aching muscles, and problems with memory and concentration. Others include heart palpitations, dizziness, anxiety and depression. Having a mild first illness does not rule it out, as the chance of long-term symptoms does not seem to be linked to how ill someone was at first.

The NHS says there is no cure, but treatment can help manage symptoms, and physiotherapy for breathing or tiredness is one option. For persistent symptoms the route is a GP appointment; a GP can assess the symptoms, and specialist post-COVID services exist for people whose symptoms have a big impact on their lives. For worsening acute illness, the NHS says to contact a GP or NHS 111 urgently. Call 999 or go to A&E for sudden chest pain, severe breathlessness, coughing up blood, or collapsing.

Frequently asked questions