Comorbidities and COVID: A much higher risk of death

While some countries are vaccinating their way out of the COVID-19 pandemic and are starting to see an easing of restrictions, other countries in South Asia are experiencing a new wave of infections that are causing devastation to their populations and healthcare systems.

Those most at risk of developing severe complications – and even of dying – as a result of the virus remain the most vulnerable members of our societies.

It is thought the immune system of older people – those over 65 – is slower to respond to the virus, leading to a longer period of infection and inflammation as a result of the disease. This prolonged period also allows the virus to replicate and overwhelm the immune system and internal organs, resulting in poorer outcomes.

But certain underlying health conditions, known as “comorbidities”, also increase your risk of becoming seriously ill as a result of catching COVID-19. Serious illness could mean a person will need hospitalisation, intensive care or a ventilator to help them breathe, or they may even die.

When looking at which illnesses increase a person’s risk of severe disease from COVID-19, it is important to remember that people with underlying health conditions also tend to be older so age as well as their health plays a part.

 Heart disease

Studies show that high blood pressure and cardiovascular disease are high up on the list of underlying health conditions that can make a COVID-19 infection worse. About 10 percent of patients with pre-existing heart disease – otherwise known as cardiovascular disease (CVD) – who contract COVID-19 will die, compared with only 1 percent of patients who are otherwise healthy.

Severe viral illness puts increased demands on the heart. When the virus causes inflammation and infection in the lungs, they are not as efficient at doing their job of gas exchange as before the infection. This leads to blood oxygen levels dropping. When this happens, the heart must work harder to pump what oxygen there is in the blood around the body to meet the demands of the rest of the organs. This can tire and weaken the heart and, if a pre-existing heart condition exists, this will only serve to worsen the problem.

COVID-19 can also cause inflammation of the heart muscle, a condition known as myocarditis and this, in turn, can lead to dangerous heart rhythms.

There is no special protocol for people with heart conditions to protect themselves from COVID-19, but following local guidance on social distancing is recommended, as well as keeping up to date with flu and pneumonia vaccines to help you keep as healthy as possible.


Diabetes describes a spectrum of conditions that result in insulin levels falling too low or rising too high. Insulin is a hormone needed to control blood sugars at an optimal level for the body to function. Everyone with diabetes, regardless of which type, is more vulnerable to developing a severe illness or even dying if they do get COVID-19, but the way it affects a person will vary from individual to individual. If blood sugars rise too high or fall too low, problems can develop. Simultaneously, if insulin levels become too high, this can also adversely affect the body’s ability to fight off infections.

The reasons that having diabetes increases the risk of death from COVID-19 are varied and complex. Often, those who have had poorly controlled diabetes for many years have seen their high blood sugars cause damage to nerves and blood vessels around their body. This results in widespread inflammation; blood vessels become fragile and do not ferry blood and nutrients around the body as well as they should.

 All of this affects the overall health of the immune system, meaning it is unable to react to infections as well as in those without diabetes. This is why people with diabetes are often referred to as being “immunocompromised” (having a weaker immune system).

People with type 2 diabetes have a higher chance of being overweight or obese. This usually means their heart and lungs are less healthy and less able to help the body fight off infection. Having a high level of fat in the body can also cause inflammation, which affects the immune system’s ability to work at an optimal level.

If you have diabetes, contracting any infection can adversely affect your body’s ability to control blood sugars. A coronavirus infection can cause blood sugars to become dangerously high as insulin levels become erratic; these high blood sugars can trigger dangerous “events” in the body including the blood becoming acidotic (when fluids contain too much acid) and damage to the kidneys. This will further compromise the immune system, leading to a higher chance of complications from the coronavirus infection.

The better controlled your diabetes is, the better your chances of coming through COVID-19 without developing dangerous complications. Being on the right treatment, alongside a healthy diet and good levels of exercise in order to keep weight at an optimal level are key.

 Lung disease

Having a chronic lung condition is another risk factor for becoming seriously unwell with COVID-19. Lung conditions that increase this risk include: asthma, if it’s moderate to severe; chronic obstructive pulmonary disease (COPD), including emphysema and chronic bronchitis; damaged or scarred lung tissue such as interstitial lung disease – including idiopathic pulmonary fibrosis; cystic fibrosis, with or without lung or other solid organ transplant; and pulmonary hypertension – high blood pressure in the lungs.

In general terms, the more severe the lung condition, the higher the risk of serious illness from COVID-19, which is primarily a disease of the lungs. COVID-19 can cause a condition known as Acute Respiratory Distress Syndrome (ARDS), which occurs when an infection causes fluid to build up in the lungs, affecting the exchange of oxygen and carbon dioxide, this can cause people to become short of breath and for their blood oxygen levels to drop to dangerously low levels.

If the lungs are already underperforming because of a previous or underlying lung condition then they are likely to become overwhelmed and ARDS can set in sooner. There are studies to suggest those with the common lung condition, chronic pulmonary airway disease – usually caused by damage due to smoking tobacco – have an increased number of ACE2 receptors in parts of their airways. These are the receptors that the coronavirus spike protein binds to in order to enter human cells and cause an infection. The more of these receptors, the higher the risk of infection.

The best advice to anyone, regardless of whether they have an underlying lung condition or not, is to stop smoking. This is the kindest thing you can do for your lungs. Many of the lung conditions listed are not caused by smoking, in which case sticking to social distancing measures and making sure you are on the right treatment in order to manage your lung condition is key.

There are many other comorbidities that increase the risk of developing serious illness from COVID-19, including certain cancers, immune system disorders and kidney disease. Whatever the risk, as always reducing your risk through mask-wearing, social distancing and going for the vaccine when called is absolutely key.