Why are Certain Individuals at a Higher Risk of Being Affected by a SARS CoV-2 Infection?
Coronavirus disease 2019 (COVID-19) has affected large parts of the world and has now reached pandemic status. As of the 22nd of May, the SARS-CoV-2 virus had spread to 188 countries with over 5 million cases and more than 300,000 deaths worldwide.
This disease is caused by a respiratory virus called severe acute respiratory syndrome coronavirus 2 (SARS CoV-2). More data is emerging on the variability of outcomes caused by COVID-19. The infection affects populations and individuals in different ways, and this seems to be dependent on a combination of biological, socioeconomic or sociodemographic factors, which may or may not be linked to underlying health conditions. Some individuals may be infected with the virus and not experience any symptoms, whilst the same infection in others may cause severe respiratory disease, multi-organ failure and death.
The available data surrounding the signs and risks of infection by SARS CoV-2, as well as the outcomes and treatments of COVID-19, is continuously evolving. Provision of updated, evidence-based, information using the most recent clinical research and data will help mitigate the spread of the infection, and protect those who are more vulnerable around us.
Watching out for the most common signs of the infection such as a fever, cough and shortness of breath, even if the symptoms are mild, is paramount to protecting yourself and others. Staying at home, and maintaining self-isolation and distancing measures if you have any symptoms of COVID-19 reduces the risk of infecting others . If you are living with others and know that you have been infected, wear a mask in their presence to limit their exposure and ask them to do the same. If possible, stay at least 2 metres away from others at home, limit contamination of surfaces and other communal facilities, and avoid sharing household items. These measures are particularly important for those who are at increased risk of severe disease once infected with the virus.
This article provides an outline of the different risk factors that make individuals more vulnerable to the acquisition of severe or critical symptoms following infection with SARS CoV-2, based on the most current reports and research.
Demographics
Characteristics such as gender, age, and weight have been shown to contribute to the way that a person responds once exposed to, or infected with, SARS CoV-2. Case-fatality rates, defined as the rate of death from COVID-19 from the total number of diagnosed cases, vary worldwide. Data gathered to date by Johns Hopkins University show that case-fatality rates range from 0-16% by country, suggesting that there are ethnic and socioeconomic factors that contribute to the risk of dying from COVID-19. As more data emerges, and with further research, the clinical and scientific community will begin to understand the role that genetic, social, and cultural factors play in controlling the rates and outcomes of infection. To date, three main demographic factors present disproportionate risks as summarised below.
Gender
COVID-19 appears to adversely affect the male population more than the female. Men are at increased risk of developing moderate to severe symptoms once infected with the SARS CoV-2 virus. As a result, data published to date is showing that men are, on average, twice as likely to be critically hospitalised or die once infected by the virus. More research is required to understand how females are more protected from SARS CoV-2 than men, but it is possible to extrapolate this based on the fact that the X chromosome carries a number of important genes that have an important role in the regulation of the immune system. Therefore, the reduced susceptibility of females to the acquisition of symptoms associated with viral infection can be attributed to the X chromosome. In males, the presence of a single X chromosome, compared to the two copies that females carry, means that they can be more immuno-compromised under certain conditions.
There are also lifestyle and cultural aspects which can put men in a higher risk category than women such as smoking and alcohol.
Age
Individuals of any age can contract SARS CoV-2, with or without becoming symptomatic. To date, COVID-19 has affected significantly more individuals in the 65 and over age bracket, and less of the younger population. Studies have shown that advanced age puts individuals at a higher risk of experiencing severe symptoms once infected with SARS CoV-2; meaning that this age group is more likely to require hospitalisation.
Age also correlates with the acquisition of non-communicable disorders such as hypertension, chronic renal disease and diabetes. In the context of COVID-19, over 70% of those who have been hospitalised with the infection over the age of 65 have at least one underlying health condition. In general, the ability of our bodies to regenerate slows down with age, and this applies to all organs, including the skin, gastrointestinal tract, liver and immune system. As a result, the older you are, the less likely your body is able to effectively or rapidly clear infections.
Maintaining a balanced diet and partaking in regular exercise gives you a better chance of maintaining a healthy body to fight infections. This is particularly important if you are in the older population group. However, despite the clear correlation between age and disease severity, certain young adults and children can also experience critical symptoms following infection with SARS CoV-2 for reasons that are not yet well understood. Caution, protection and healthy lifestyle choices must be adopted by all.
Body Mass Index
Your body weight can be used as an indicator to determine how at risk you are of developing severe or critical COVID-19 symptoms. An optimal Body Mass Index (BMI) is 18.5-24.9 kg/m2 and if you lie within this range, you are considered to have a healthy weight. People in this category have enough body fat to function effectively. Body fat, or adipose tissue, is an essential component of every organ and cell in our body; it has multiple roles, including insulation, energy storage, and the maintenance of hormones. Fat cells are also a source of stem cells which can differentiate into other cell types, such as bone and nerve cells, as required. These stem cells therefore, have regenerative capabilities which are able to replace damaged or otherwise compromised tissues in our body as needed. Overweight individuals with a BMI above 25 kg/m2 and obese individuals with a BMI above 30 kg/m2 are at higher risk of developing multiple health disorders, such as cardiovascular disease, stroke, and cancer. They are also more likely to be severely or chronically symptomatic if infected by SARS CoV-2. Having an excess of body fat means you are likely to be in a chronic state of low-grade inflammation, which can impair your immune system’s response to infection. If infected, the obese are more likely to be hospitalised because their bodies are unable to fight the infection effectively, either as a direct correlation of excess body fat, or as an indirect correlation with the other health disorders that accompany obesity and which put individuals at a higher risk.
If you have a BMI below 18.5 kg/m2 you are classed as being underweight, meaning that your body is not storing enough body fat, giving you less overall protection. Being underweight weakens your immune system and puts you at increased risk of developing severe COVID-19 symptoms. Individuals who are underweight may be malnourished, and as a result may lack some of the essential nutrients, vitamins and minerals necessary for their cells and organs to function properly. This makes them more vulnerable to any external challenges or insults, such as complications arising from infection with a virus.
Obese, overweight and underweight individuals should consider contacting a local healthcare provider and a nutritionist who can help them make a healthy and monitored weight loss or gain plan.
Underlying health conditions
COVID-19 has shown selectivity towards vulnerable individuals with underlying non-communicable disorders (NCDs). Some of the most prevalent NCDs include type 2 diabetes, hypertension, cardiovascular disease, chronic lung conditions, chronic kidney disease, chronic liver disease and cancer. This trend is consistent world-wide, as more statistics on patients emerge from the clinical and scientific community at large.
Here, we outline a number of NCDs which have been shown to impact responses to the infection, and explore why individuals with these conditions are at risk of more severe COVID-19 symptoms.
Diabetes mellitus
If you have diabetes, you are unable to properly regulate blood glucose levels due to insufficient insulin production or reduced insulin sensitivity. Lack of insulin, or the inability of cells to respond to insulin, results in high blood glucose levels which puts you in a hyperglycaemic state. Under normal conditions, one of insulin’s functions (it has many others) is to signal your body to activate white blood cells, which are the main cells in our blood and lymph nodes that fight infections. Therefore, when the body is unable to produce sufficient amounts of insulin, a dysfunction of the immune system may occur, putting the individual at risk. A compromised immune system will be less able to control the spread of, and manage the symptoms associated with, invading pathogens such as SARS CoV-2.
Being in a hyperglycemic state puts pressure on one’s body, which can result in damage to multiple organs such as the heart, kidney and nervous system . Individuals with either type 1 or type 2 diabetes are, therefore, at higher risks of developing health complications such as the acquisition of cardiovascular disease, renal disease and peripheral nerve damage which also in turn put them at a higher risk of being negatively affected by infections and other external pressures.
If you are diabetic, it is important to keep taking your medications as required. Those who are on insulin replacement therapy should monitor their body’s sensitivity to insulin which may determine the appropriate dose of insulin to take in order to avoid being in either a hyper- or hypo-glycaemic state. This is particularly important if you have been infected with SARS CoV-2.
Cardiovascular disease
The highest numbers of patients who have been hospitalised with severe or chronic COVID-19 have had hypertension or another type of cardiovascular disease (CVD). Autopsy results from patients who have died with or from the disease show evidence of myocarditis, defined by the presence of unusual inflammatory cells in the heart. Individuals hospitalised due to the infection also show markers of cardiac injury in their blood and this is seen in patients with and without a pre-existing history of CVD, suggesting that the virus puts pressure on the heart muscles, even in those with no known prior heart issues.
Heart failure can occur when your heart muscle doesn’t pump blood as efficiently as it normally does. When combined with arrhythmia, which is a common feature seen in vulnerable individuals infected with SARS CoV-2, it puts pressure on the heart and affects how well it functions. There are recent findings that suggest that blood clotting events which are a characteristic of COVID-19 disease progression, are also responsible for some of the cardiovascular events observed in individuals who have died from the infection. This is supported by evidence suggesting that individuals who are on blood thinning medication have significantly improved survival rates compared to those who are not on medication. It is well established that inflammation contributes to cardiovascular disease progression. Perpetual inflammation can also damage the heart muscle and exhaust the immune system. Having a compromised heart and a dysfunctional immune system are likely to be the main contributory factors leading to cardiac failure in COVID-19 patients.
Chronic Lung Conditions
Having long-term conditions that result in recurrent inflammation in the lungs such as asthma, Chronic Obstructive Pulmonary Disorder (COPD), and cystic fibrosis (CF) make individuals more susceptible to respiratory lung infections. The lungs are home to specialised white blood cells which help to protect them from inhaled pathogens and toxins under normal circumstances. However, individuals who have compromised lungs, either due to perpetual inflammation or abnormal function of the epithelium in the lungs, may result in a state of immune and tissue exhaustion and damage; making the lungs more vulnerable to infection or challenge. In addition, controlling lung inflammation in individuals with chronic or acute asthma may require the individual to use immunosuppressive medications such as steroids, which will dampen the immune response and make them more vulnerable to infection. In general, the more chronic the condition, the more likely that a person is compromised, either due to long term medication use or as a result of the pressure the disease poses on lung tissue.
Individuals with CF are at a high risk of developing other lung complications because the disease is caused by a genetic dysfunction which affects the level of salt in cells. This leads to water imbalance which can clog up highly vascular organs such as the lungs and digestive tract. In the lungs, this affects the air flow in and out of the lungs, resulting in respiratory distress. As COVID-19 is predominantly a respiratory disease, not having the necessary protection mechanisms in place within the lungs puts individuals at a higher risk of developing severe respiratory disease if infected with SARS CoV-2.
You should continue to take your medications but take extra care to protect yourself. If you are a smoker, it is highly recommended you stop smoking to give your lungs a better chance to control and recover from the infection (see smoking section).
Cancer
Blood cancer is caused by a dysfunction in white or red blood cell production from the bone marrow or lymph nodes. Leukaemia, lymphoma and myeloma are white blood cell cancers. The white blood cells normally fight infections, and if they are dysfunctional, your body is less able to fight infections efficiently.
Polycemia vera is a rare cancer and a type of red blood cell cancer. The red blood cells help to carry oxygen to the rest of your body. Having any cancer of the blood puts you at a higher risk of experiencing severe symptoms once infected with SARS CoV-2.
Cancers that affect other major organs, such as the lungs, kidneys or liver also place individuals at a higher risk, as those organs are unable to function properly if malignant. The fact that COVID-19 is a respiratory disease means that those with compromised lungs, either due to cancer or other conditions, are likely to be severely affected if infected. See the lung, liver and kidney sections of this report.
In general, people who have cancer are immunosuppressed either due to the cancer itself or the treatment they are undergoing. Individuals with stable disease may wish to discuss the option of delaying chemotherapy or elective therapy with their oncologist until the threat of COVID-19 is reduced. Individuals with progressive, aggressive or metastatic disease requiring treatment should take extra caution to protect themselves and self-isolate. See immunosuppressive treatment section for further information.
Liver Disease
Having chronic liver disease may put you at risk of experiencing severe symptoms once infected with SARS CoV-2. Compromised blood liver functions are a common feature in individuals who are critically hospitalised with COVID-19. The liver is an essential detoxifying organ. Its primary function is to filter blood from the digestive tract and the rest of the body. The liver also stores and releases glucose as needed, makes cholesterol, and stores iron. The liver holds certain types of white blood cells, and supports immune function by clearing infections. Liver disease involves a process of progressive destruction and regeneration of the liver, often leading to scarring and permanent damage. This progressive liver damage often causes a dysfunction in metabolism, leading to insulin resistance or impaired insulin production (see diabetes section). This in turn affects the immune system and the ability of the body to clear infection, thus hindering the way the body responds to infectious pathogens such as SARS CoV-2.
Kidney Disease
As more data emerges on the clinical characteristics of individuals who have been hospitalised or who have died from COVID-19, it is becoming apparent that the most affected organs, after the lungs, are the kidneys. Kidney disease occurs when the kidneys are unable to filter out water and waste from the blood effectively. The filtration of waste products is a natural part of the metabolic process; therefore, factors such as medication, environmental pollution and infection that add to waste generation, also add to the pressure on the kidneys to work efficiently and effectively. Kidneys have historically been thought of as organs that are unable to regenerate, but new research shows that they do have regenerative capabilities, but this process is likely to be slow. As cellular turnover slows down naturally with age, and because age is directly associated with acquisition of kidney disease (see age section), recent reports from the USA show that most of the COVID-19-related deaths to date in individuals over 65 have concurrent kidney failure as the main cause of mortality. If compromised kidney function means that the body is not able to effectively filter invading pathogens and toxins, infection with SARS CoV-2 will put additional pressure on the kidneys, potentially leading to kidney damage and toxic shock which will require immediate hospitalisation.
Individuals with NCDs such as kidney disease should take their conditions very seriously and talk to a designated healthcare provider about putting appropriate measures in place to protect themselves. Maintaining good hydration and a healthy lifestyle is key.
Other factors
HIV/ AIDS
Testing positive for Human Immunodeficiency Virus (HIV) does not make you more susceptible to developing severe COVID-19 symptoms, provided you are on effective antiretroviral treatment. However, if you are not on appropriate treatment, the HIV virus is free to attack your immune system, putting you at a higher risk of developing AIDS. AIDS stands for Acquired Immuno-Deficiency Syndrome. As the name indicates, this is a progressive condition that results in destruction of the immune system. Without a functioning immune system, you will become immunocompromised, meaning that it will be more difficult for your body to fight an infection. This increases the likelihood of you experiencing more severe symptoms, should you become infected with SARS CoV-19, of. If you have HIV you should already be under care of an appropriate healthcare provider who can properly monitor your condition.
Smoking
Tobacco smoke exposure increases susceptibility to respiratory tract infections such as COVID-19. Smoking is known to damage the lungs and airways which causes a range of severe respiratory problems (see chronic lung conditions), it also puts you at a high risk of developing lung cancer and cardiovascular disease, the latter is the risk factor most frequently seen in those individuals who have died from COVID-19. Smoking does not only directly affect you, it also puts those around you who are exposed to secondhand smoke at risk. In light of the current pandemic, there has never been a more important time to stop smoking, not only for your own health, but also to protect those around you.
If you are using e-cigarettes or other ‘vaping’ devices, recent clinical and scientific evidence has suggested that these pose a similar threat to the health of your lungs and heart. E-cigarettes contain chemicals that are not present in traditional cigarettes, but which have additional health implications associated with them. E-cigarettes also carry an additional hygiene risk due to reuse of mouth pieces, which means you are more likely to expose yourself to pathogens, such as SARS-CoV-2, which can survive on a variety of surfaces.
Immunosuppressive medication or treatment
There are many medications, treatments and medical procedures that can temporarily reduce the ability of your immune system to fight infection. In this section, we will provide a few examples; however, if you are on any medication or have undergone a medical procedure recently which makes you immune compromised, you should be in regular contact with your healthcare provider. They will be able to determine how vulnerable you are to acquiring severe or critical COVID-19 symptoms and advise you which steps to take to reduce your chances of catching this, or any, infection.
- Immunosuppressants
Drugs that suppress the immune system such as certain biologics (recombinant proteins) and glucocorticoids (steroids), inhibit white blood cells activity or function. These cells are the main fighters of infection in the body and, therefore, taking drugs that stop them from working effectively or reduce their numbers, affects the ability of the immune system to fight infection. This makes you more susceptible to severe symptoms following infection with SARS CoV-2.
One of the most widely used treatments for cancer is chemotherapy. The mechanism of chemotherapeutic agents is to destroy rapidly growing cells by damaging DNA and other factors involved in cell division. Because of its mechanism of action, chemotherapy also attacks the highly dividing and healthy cells of the body such as the stem cells of the bone marrow. These stem cells are responsible for providing a continuous supply of the disease fighting, white blood cells. During and immediately after chemotherapy your body is less able to defend itself against infection. Individuals who have certain types of cancer may already be at an increased risk of experiencing severe COVID-19 symptoms; and if the same individual is also undergoing chemotherapy, extra protection and caution should be considered.
- Bone marrow transplantation is a procedure that aims to replace otherwise damaged or destroyed bone marrow with healthy bone marrow. The first step involves radiotherapy to partially or completely eliminate faulty stem cells. The aim is to reintroduce healthier bone marrow via a transplant. As described above, the bone marrow is an essential source of infection-fighting white blood cells. The period between bone marrow elimination and transplant acceptance (i.e. the body adjusting to its new, healthier bone marrow) is around 6 weeks, and this can vary from person to person. During this critical time, a transplant recipient is at extremely high risk of acquiring infections. This includes infection with SARS CoV-2.
Living in a care facility or nursing home
Nursing home populations are at the highest risk of being affected by COVID-19 compared to the general population because they have a high proportion of older adults who are often living with underlying chronic medical conditions which puts them at risk of experiencing severe or chronic symptoms if infected with SARS-CoV-2. To protect all who live and work in nursing homes and care facilities, regular cleaning and disinfection of common areas, appropriate social distancing, and self-isolation measures where required, should be implemented. It is important that carers, who may carry the virus but may not be at risk themselves, also take the necessary steps to protect those residents who are considered high risk. This includes social distancing as much as possible and wearing appropriate Personal Protective Equipment (PPE).
Working in a healthcare environment
Being a doctor, nurse or an individual working in a hospital or clinic means that you may have regular exposure to patients who may have tested positive for SARS CoV-2 and, therefore, there is a risk of them passing the infection on to you. Take sensible precautions when handling infected patients; use PPE when at work, such as masks, a clinical coat/suit and gloves, and ensure that it is changed on a regular basis. Outside of work, take steps to protect yourself and those around you who may be vulnerable to infection. Use best practice for maintaining hygiene, including removal of potentially contaminated clothing whilst still at work, washing hands with soap and water, and disinfecting any other materials that may come in contact with others outside the hospital setting.
Contact with an infected or exposed individual / environment
Being in close contact with someone who has COVID-19, or someone who has been exposed to the SARS CoV-2 virus, puts you at high risk of infection, which is increased if you have other confounding factors, such as those mentioned in this article. Because the majority of individuals who are exposed to the virus do not display obvious symptoms, extra care to protect yourself should be taken if you are in a high risk category.
Based on current data surrounding the length of time the virus remains in our bodies (the incubation period), you should self-isolate for at least 14 days from the time of potential exposure (Day 0) to minimise passing the infection to others.
Conclusion
As this article shows, many of the factors that result in an individual becoming ‘high risk’ occur as a result of underlying health conditions. Therefore, it is important to ensure that your current health status is under control and that medication, where required, is taken appropriately.
Being aware of the signs of infection such as a fever, cough, shortness of breath, is key. Call ahead before visiting a health care provider or emergency department to alert them to the fact that you have been exposed to the virus. If you are in a country which has implemented tools to alert or monitor infected or potentially infected individuals, you may wish to adopt some of those tools to protect those around you and reduce the chance of cross contamination.
The general recommendation is to limit hospital visits and contact with healthcare facilities where ever possible. If you have a chronic condition and require ongoing medical care or monitoring, provided your doctor is okay with it, consider using telehealth, electronic consultations and remote care, as appropriate. If you are considered high risk and require medications or a pharmacy visit, think about asking others who are less vulnerable to pick up what is needed. It is important to keep taking your medications as recommended.
Nabta Health is committed to providing you with the most up to date, peer-reviewed, clinically- and scientifically-validated information on COVID-19 and other conditions. If you are not sure what your, or your loved ones’, risk factors are, Nabta Health has built a risk assessment questionnaire, which can be accessed from our Application. The Nabta App can be downloaded from our website (www.nabtahealth.com).
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