What is Coronavirus?

Coronaviruses are a large family of viruses that can cause illness ranging from a mild common cold through to more serious respiratory conditions such as Middle East Respiratory Syndrome (MERS) and Severe Acute Respiratory Syndrome (SARS). The virus behind COVID-19, SARS-CoV-2, was first identified in December 2019 in Wuhan, China. It was described as a novel coronavirus because it had not previously been seen in humans, which meant nobody had any existing immunity to it.

How the outbreak developed

Within a few months of being identified, the virus had spread to almost every country in the world and in March 2020 the World Health Organization declared COVID-19 a global pandemic. That speed of spread was partly down to how easily the virus passes between people and partly down to how much international travel there is in the modern world.

COVID-19 spreads mainly through respiratory droplets released when an infected person coughs, sneezes, talks or breathes heavily nearby. It can also spread by touching a contaminated surface and then touching your mouth, nose or eyes, although this route is considered much less significant than direct airborne transmission. Poorly ventilated indoor spaces with lots of people tend to carry the highest risk.

Common symptoms

Symptoms of COVID-19 vary quite a bit from person to person. Common ones include:

• A high temperature or chills
• A new, continuous cough
• Loss or change to your sense of smell or taste
• Shortness of breath
• Fatigue or unusual tiredness
• Aching muscles or joints
• A sore throat, headache or blocked nose

Many people experience only mild, cold-like symptoms, or none at all. In more severe cases the virus can lead to pneumonia, which is when the lungs become inflamed and filled with fluid, making breathing difficult. This is the point at which COVID-19 becomes potentially life-threatening, particularly for older adults and people with existing health conditions.

Who is most at risk

Anyone can catch COVID-19, but certain groups are more likely to become seriously unwell. This includes people over 60, those with conditions such as diabetes, heart disease, chronic lung disease, or a weakened immune system and people who are significantly overweight. Pregnancy can also increase the risk of complications, which is why pregnant women are usually offered vaccination as a precaution.

Diagnosis and treatment

COVID-19 is usually diagnosed with a PCR or lateral flow test, both of which detect the virus from a nose or throat swab. There is no single cure for COVID-19. Treatment is largely supportive, meaning it focuses on easing symptoms while your immune system deals with the infection: rest, fluids and over-the-counter medication for fever and aches. In more serious cases, hospital treatment may include oxygen therapy, antiviral medicines or other supportive care.

Reducing your risk

The basics that were drilled into everyone during the pandemic still hold up well against COVID-19 and most other respiratory viruses:

• Wash your hands regularly, particularly after being in public places
• Cover coughs and sneezes and dispose of tissues promptly
• Stay away from others while you're unwell, particularly anyone vulnerable
• Keep indoor spaces well ventilated where you can
• Keep up to date with vaccinations if you're in an eligible group

If you're unsure whether your symptoms need medical attention, NHS 111 is a good first port of call and you should always seek emergency care if you're struggling to breathe, have persistent chest pain, or feel confused or extremely unwell.

How coronaviruses got their name

The name "coronavirus" comes from the Latin word for crown, corona. Under an electron microscope, these viruses are covered in club-shaped spike proteins that stick out from their surface, giving them a halo or crown-like appearance. Those same spike proteins are what the virus uses to latch onto and enter human cells and they're also the main target that most COVID-19 vaccines are designed around.

Incubation period and how long symptoms last

The incubation period is the time between catching the virus and symptoms first appearing. For COVID-19, this has typically ranged from around two to fourteen days, though most people who develop symptoms do so within about five days of exposure. This can vary between variants, with some more recent strains showing a somewhat shorter average incubation period than the original virus.

Once symptoms begin, most people feel unwell for around one to two weeks, with cough and fatigue sometimes lingering a little longer than other symptoms. People are generally considered most infectious in the day or two before symptoms start and the first few days after, though this varies from person to person.

Testing options explained

Two main types of test have been used to diagnose COVID-19. PCR (polymerase chain reaction) tests are processed in a laboratory and are highly accurate, detecting even small amounts of viral genetic material, though results usually take a day or more to come back. Lateral flow tests give a result within around fifteen to thirty minutes and can be done at home, but they're somewhat less sensitive, meaning they can occasionally miss an infection, particularly very early or very late in the illness. Both work by swabbing the nose, throat, or both.

Frequently asked questions

Can you get COVID-19 more than once?

Yes. Immunity from a previous infection or from vaccination doesn't guarantee protection against reinfection, particularly as new variants emerge that differ from earlier versions of the virus. Reinfections are generally, though not always, milder than a first infection.

How long are you infectious for?

This varies, but many people are no longer considered significantly infectious around five days after symptoms begin, particularly once a fever has settled. People with weakened immune systems may remain infectious for longer.

Is COVID-19 airborne?

Yes, current evidence indicates the virus can spread through both larger respiratory droplets and smaller airborne particles that can linger in indoor air, which is part of why ventilation makes such a difference to transmission risk.

Recovery and returning to normal activities

Most people recover from COVID-19 within one to two weeks without needing hospital treatment. General guidance during recovery is to rest, stay hydrated and gradually return to normal activity as you start to feel better, rather than pushing straight back into strenuous exercise the moment symptoms ease. Some people notice their energy takes a little longer to fully return than the main symptoms did, which is fairly normal after most respiratory infections.

There's no fixed rule for exactly when it's safe to return to work, school or social activities, since it depends on how you're feeling and whether you're likely to come into contact with anyone particularly vulnerable. General advice is to wait until any fever has settled and you're feeling significantly better before resuming close contact with others and to consider wearing a mask around vulnerable people for a short period afterwards as an extra precaution.

If your symptoms persist beyond a few weeks or you develop new symptoms such as ongoing fatigue or breathlessness, it's worth speaking to your GP, since this could be a sign of long COVID rather than a normal recovery.

Who should get tested when unwell

Testing is most useful for people at higher risk of severe illness, people planning contact with someone vulnerable and healthcare or care workers. If you're generally healthy and not around anyone at higher risk, general advice is simply to stay home and rest until you feel better, regardless of the exact cause. If you do want to test, home lateral flow kits remain available from most pharmacies.