As cases of coronavirus continue to rise, it's vital to know who is at greatest risk. People with underlying health conditions are more likely to experience worse symptoms or develop complications if they contract COVID-19 - here doctors explain why.

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With coronavirus dominating the news lately you'd be forgiven for worrying about whether you're at a greater risk of catching the virus. The truth is, some groups are more at risk, and more likely to experience a serious illness, including those with underlying health conditions. Dr Roger Henderson, GP and medical director at Liva Healthcare, and Dr Diana Gall, from online service Doctor 4 U, explain more.

What is an underlying health condition?

An underlying health condition is a chronic or long-term illness, which in turn weakens the immune system.

"This refers to a medical problem that is usually chronic or significant, and which usually requires long-term treatment," Dr Henderson says.

As it weakens the immune system, it puts people at greater risk of serious complicatons of infectious illness - and with coronavirus spreading, those with underlying health conditions are at greater risk.

"Underlying chronic health conditions such as heart disease, diabetes and lung disease can affect the immune system. This reduces the body's ability to fight off infection or illness, so the symptoms and impact from infection can be worse," Dr Henderson says.

Dr Gall adds: "With the immune system already tackling another long-term illness this affects your body's ability to respond as quickly to exterior factors, which puts these individuals at a greater risk of contracting further illnesses if exposed."

Coronavirus and underlying conditions

"Coronavirus can affect everyone. But those with chronic health problems are more at risk because they are typically older. Older patients seem particularly vulnerable to coronavirus, especially those over the age of 80," Dr Henderson explains.

"This can be coupled with an underlying health condition, putting their immune system under increased pressure."

This means their bodies are not "well equipped" to deal with COVID-19, Gall says.

"That means that while the symptoms may come across as fairly mild, to one person they may be potentially deadly, especially to those with chronic respiratory problems or heart disease, whose organs aren't functioning at full capacity."

The risk groups

So, we know that those with underlying health conditions are at greater risk, but which particular conditions put a person at greater risk?

As coronavirus is a respiratory disease, those with respiratory conditions are at greater risk, along with those who are immunocompromised.

"While there are hundreds of health conditions which may affect immune function, conditions such as heart disease, chronic respiratory disease, diabetes, cancer and high blood pressure have seen the highest number of fatalities from the pandemic," Dr Gall says.

"Reasons for this lie with the aggressiveness of the conditions themselves and how they are already affecting the body's ability to fight off illnesses.

"Studies have shown that patients with heart disease are more likely to get increased blood pressure and heart rates that can lead to heart attacks and strokes.

"And for those with respiratory problems, the cough associated with coronavirus could be deadly as there could be limited types of drugs which doctors are allowed to use."

The government recommends that as a rule of thumb, anyone eligible for a free flu vaccine should consider themselves in an at risk group.

Are there degrees of risk?

The government has recommended that 1.5 million people in the UK at highest risk of complications from coronavirus should stay at home and not go out under any circumstances. They should also be avoiding any contact within their home unless it's essential (eg if they have carers who need to perform personal care tasks) or unless the person they live with is doing the same. This is called 'shielding'.

These are people whose immune system is most compromised - either because of illness such as sickle cell disease or cystic fibrosis, or because of treatment such as cancer therapies or organ transplant rejection medication.

Self-care

If you're someone who has an underlying health condition it's important you're taking steps to prevent your risk of exposure to the virus, including taking on board social distancing and self-isolation advice.

"Follow the government's advice around hand washing and strict hygiene, avoid touching your face whenever possible, stay rested and well hydrated, try to eat a healthy diet rich in fruit and vegetables, and exercise if possible, even if that means doing it indoors," Dr Henderson says.

New restrictions by the UK government mean that the public must stay in their homes and only leave for few, specific reasons including once daily exercise, shopping for food and medicines, work which cannot be done from home and for medical care. For people with underlying health conditions, even shopping for food and medicines should be left to others if at all possible.

Everyone should avoid all contact with people outside of their household wherever possible, including maintaining a two metre distance between them and another person. This is especially important for people with underlying health conditions. If you can, you should avoid leaving your house entirely and arrange for groceries and medication to be delivered to you. This is to minimise your exposure to the virus.

If you or anyone in your household becomes unwell, you should self-isolate and not leave your house. The person with symptoms needs to self-isolate for at least seven days, while anyone living in the house needs to self-isolate for at least 14 days. You can find out more from the Patient Access Coronavirus checker tool.

"Self-isolation is particularly crucial at the moment with numbers here rising everyday, so make sure to seek help from loved ones with things such as grocery shopping and other errands," adds Dr Gall.

Seeking medical attention

If you need to see a GP, take note of the latest guidance from your practice or local pharmacy or on their website. Some surgeries have stopped face-to-face appointments and are turning to video or telephone appointments. Others have switched off online appointment booking. Many non-urgent appointments will be cancelled as GP practices are more busy as a result of the pandemic.

If you need medication, pharmacies are functioning as usual but will be busier than they normally are. If you are self-isolating or can't attend in person to pick up your prescription, ask someone to pick it up on your behalf. Some pharmacies are still able to offer a home delivery service.

If you experience any symptoms of fever or new, continuous cough, self-isolate and avoid all contact with other people until you have used Patient's coronavirus checker tool to find out what to do next.

Help from NHS volunteers

Many people who have to stay home for their own protection can now access help from the 750,000 NHS volunteers who have signed up to help. The services NHS volunteers can offer include:

Collecting and delivering shopping and other essential supplies.

Delivering medicines from pharmacies.

Driving patients to appointments.

Bringing them home from hospital.

Making regular phone calls to check on people isolating at home.

Transporting medical supplies and equipment for the NHS.

People who are eligible for help include:

Anyone who has been advised to self-isolate and shield themselves.

Over-70s who have underlying health conditions such as heart disease, diabetes, COPD, liver or kidney problems, or nervous system conditions such as Parkinson’s disease or multiple sclerosis.

People who are self-isolating who GPs consider especially vulnerable.

If you think you may be eligible, please contact your GP practice (or social care provider if you have one). They can refer you to this service.

This article was updated on 25th March following new government advice recommending that everyone should stay home where possible.