COVID-19 & the human body

COVID-19 & the human body

As with any disease, certain groups of people will be more susceptible to catching it due to different factors.

Research continues to indicate that there are several risk factors for being more vulnerable to COVID-19 and no doubt that as more about the disease is revealed these will change in terms of severity as statistics about who becomes the most affected by infection and who is more likely to die because of an infection.

There are several risk factors that are currently thought to influence a person’s vulnerability to the impact of COVID-19, which include:

  • The presence of underlying health conditions
  • Smoking
  • Obesity (with a BMI of 40 or over)
  • Sex, i.e. being a man or a woman.

It is also argued that in some instances, living in a care home is likely to increase the possibility of developing COVID-19 but a lot of research to find out why there has been such an outbreak within care homes in the UK is currently underway, and a clearer picture may not be known for some time.

Underlying health conditions

An underlying health condition refers to a condition that an individual already has at the time when they contract COVID-19.

As with a lot of other information about the disease, research is continually finding out information about which types of underlying health conditions are likely to have the most negative impact on someone who has COVID-19, and these are detailed on the following slides.


It has been found since the first outbreak of COVID-19 that, in the UK, approximately 25% of people who have died with COVID-19 also had diabetes. It is currently unclear which type of diabetes has been found most prevalent, but the figure is alarming enough to make health professionals particularly single it out as a risk factor.

COVID-19 is thought to impact people with diabetes because it puts a strain on the heart and on other organs, which may already be under strain because of the impact of diabetes. Also, whilst unconfirmed, some individuals with Type 2 diabetes may also be overweight with a high BMI, which adds to the risk factor for difficulties related to COVID-19, as having a high BMI is another risk factor.

Lung and breathing problems

COVID-19 is an illness, which primarily affects the lungs, causing complications such as pneumonia and in the most severe cases, acute respiratory syndrome. Individuals who already have lung and breathing problems are therefore more likely to be impacted by COVID-19 because their lungs are already weakened by their existing condition, making it easier for the virus to attack and affect them.

Pneumonia that COVID-19 causes tend to impact both lungs, filling them with fluid and limiting their ability to take in oxygen. This causes shortness of breath, coughing and other related symptoms.

Heart disease

Having heart disease does not make someone more likely to catch COVID-19, but it can make them become more ill because the virus places strain on the heart (because of how it puts a strain on the lungs), which may already be weakened by the effects of heart disease.

Chronic kidney disease

The reasons as to why chronic kidney disease causes more severe symptoms in people with COVID-19 are not yet fully understood; however initial thoughts are that because COVID-19 attacks internal organs, people who have weakened kidney function may be more seriously impacted because their kidneys are not effective enough to fight the disease off.

The significance of blood clots

Very recent findings have uncovered that up to 30% of people who are hospitalised with COVID-19 develop blood clots, which can be fatal if they, for example, travel to the lungs, heart, or brain. Researchers believe that this is linked to the fact that COVID-19 causes ‘sticky blood’ because blood cannot flow freely through veins whose smooth walls have been made rough by inflammation.


Whilst still very much under research, initial findings indicate that people who smoke are four times more likely to contract COVID-19 than those people who do not smoke.

Additionally, it is thought that those people who smoke and who contract COVID-19 are more likely to experience more complications than others as well. Some thoughts about this link smoking and COVID-19 since tobacco damages the lungs and airways, causing a range of respiratory problems. As COVID-19 attacks the respiratory system, this places smokers at greater risk.


Obesity, in this instance where a person has a BMI of 40 or more, is thought to increase the severity of COVID-19 but it is accepted that more research is needed to further understand how these two are linked.

It is thought that because obesity is already linked to having many different kinds of a risk factor such as heart disease and diabetes that people who have a BMI of 40 or over potentially have a range of risk factors that make them more susceptible to COVID-19.


Early research indicates that whilst men and women have an equal chance of developing COVID-19 that men are significantly more likely to become seriously ill or to die because of complications.

The reasons for this are widely unknown, but some suggestions indicate that this could be due to a difference in lifestyle factors or it may be due to the presence of more oestrogen in women which is thought to help women have more protection against the disease.