BY DR. JAVEED AHMAD TANTRAY
Recent reports have estimated that 1.7 billion people, that is more than 20 percent of the world's population is at risk of becoming severely infected with COVID-19 due to their underlying health problems such as diabetes, obesity, heart disease, and other immune-compromised conditions.
Further, COVID19 also affects people suffering from lifestyle disorders. Lifestyle disorders relate to our habits or our addictions to: Cigarettes, Beedi, ghutka (Indian tobacco), Alcohol, etc.
The consumers of these items are likely to suffer from- Non-communicable diseases (NCDs) such as: Cancers, Cardiovascular diseases, Diabetes, Hypertensions, etc. and around 40 million people are estimated to die each year that is around 70% of all deaths globally.
They are a result of a combination of factors including genetics, physiology, environment, and behaviors and now the coronavirus pandemic.
NCDs are more vulnerable to COVID-19, a lethal disease of a novel coronavirus renamed as SARS-CoV-2. These Coronaviruses are enveloped viruses, minute in size (65–125 nm in diameter) and contain a single-stranded RNA as a nucleic material, size ranging from 26 to 32kbs in length.
Increasing evidence shows that these coronaviruses are not always confined to the respiratory tract but they may also be neuroinvasive and neurotropic, with potential consequences in vulnerable populations.
The aim of this study was to evaluate the correlation between comorbidities related to lifestyle diseases and their role in the exacerbation of disease in COVID-19 patients leading to fatal outcomes.
The pathogenesis of COVID-19 is overtly complex, with multiple factors involved. In addition to the direct viral effects and inflammatory and immune factors, the down regulation of ACE2 and imbalance between the RAS and ACE2/angiotensin-(1–7)/MAS axis may also contribute to the multiple organ injuries in COVID-19.
After binding of SARS-CoV-2 to the ACE-2 receptor of the host cell, the S protein of the virus undergoes activation at a position adjacent to a fusion peptide within the S2 subunit leading to viral and host cell membrane fusion.
The spike glycoprotein of SARS-CoV-2 is a potential target for the development of specific drugs, antibodies, and vaccines. In the longer term –this disease is likely to continue to spread rapidly into and within cities and countries hence – it is suggested that there is a need to change the way we live and adapt to the new normal.
World has witnessed how COVID19 has crashed economies, disrupting our everyday life and challenged the normal health care systems. People suffering from cancers, heart patients, renal dialysis, complicated diabetic patients, chronic liver patients, asthmatics and hypertensive patients have all been devastated and shattered due to non-availability of their standard health care facilities.
In this review we attempt to describe the impact of COVID19 on vulnerable and immunocompromised populations. The vulnerable include those suffering from NCDs and other normal populations who are children or pregnant mothers.
The effects of this pandemic have also been seen on senior citizens exposing them to unimaginable situations never faced by them before.
Moreover, Lancet has predicted that globally 1 in 5 will be affected by coronavirus who are suffering from lifestyle disorders. The heightened risk of COVID19 was also reported by a team of experts from the London School of Hygiene who analyzed patients suffering from comorbidities, lifestyle diseases like diabetes, lung disease, HIV etc.
They also found that the COVID 19 had killed 420,000 people globally during the first wave could adversely affect the vulnerability of comorbid patients having at least one underlying health problem.
Pulmonary studies have detailed the pathological mechanisms due to SARSCoV-2 infections, but a detailed understanding remains elusive. A few autopsy studies of patients with COVID19 have shown that congested lungs had a patchy distribution of abnormalities on gross examination.
Further, microscopic findings included diffuse alveolar damage with hyaline membrane formation, pneumocyte activation, microvascular thrombi, lymphocytic inflammation, and proteinaceous edema. T
he impact of measures taken to contain COVID-19 on lifestyle related behaviour is undefined. Their risks factors can be divided into three primary risk sets: modifiable behavioral risk factors, non-modifiable risk factors and metabolic risk factors, many of which are common for several diseases.
Route of infection of coronavirus (SARS-CoV-2) in humans
One question which everybody is worried about is - Can an asymptomatic person transmit the diseases? This has been proven right in a Chinese study. It has been reported that transmission appears to have happened during the incubation period of the virus from an asymptomatic patient. This finding came to light when the world was witnessing an exponential spread of the virus and the question was why is the spread so rapid?
General belief which went viral was that active sneezing and coughing was the route of contaminating the surrounding and the people in its vicinity but now it is much more difficult to stop the spread because people who look well may be transmitters of the deadly virus. Once the virus enters a new host, it seeks a receptor to attach itself to the host and this is the ACE2 receptor of the host cell.
The chemistry between the virus spike protein and the ACE receptor fuse and then virus enters the cell makes millions of copies of itself by the mechanisms beautifully described by a host of Scientists and the consequences results in diseases prevalence. The result could be morbidity, mortality or recovery.
ACE-2 has been identified as a functional receptor for SARS-CoV-2 and is highly expressed on the pulmonary epithelial cells. Restoring the balance between the RAS and ACE2/angiotensin-(1–7)/MAS may help attenuate organ injuries in COVID-19.
Host’s defense system
The immune system is instrumental in protecting and fighting any external invaders of every shape and tries to destroy it. Hence when the virus appears the T cells quickly multiply to attack the virus and recruit B cells to produce antibodies which provide protection from future attacks.
This is significant because antibody signals for SARS-CoV-2 have been reported by many researchers to decline over time. Additionally, recent research has shown that the T-cell response can persist even when antibodies wane. And when the cells become infected with the virus, immune genes that fight viral infection, interferon-stimulated genes, get activated.
Clinical symptoms and pathology
The clinical spectrum of COVID-19 is quite heterogeneous, ranging from mild flu-like symptoms to acute respiratory distress syndrome, multiple organ failure and death.
The organs like brain, heart, oral and nasal mucosa, kidney, nasopharynx, colon, lymph nodes, small intestine, stomach, thymus, skin, spleen, bone marrow, liver and blood vessels, are all susceptible to be infected by COVID-19, on account of presence of abundant ACE2 in these areas of the body.10 This is especially visible in older age, diabetes and in other comorbidities that are reported as significant predictors of morbidity and mortality.
The significant defense mechanism is described as the “Cytokine Strom”, which results in chronic inflammation, increased coagulation activity, immune response impairment, and potential direct pancreatic damage by SARS-CoV-2. Early in the pandemic, high levels of inflammatory cytokines such as interleukin-6 (IL-6) were observed in patients with poor outcomes.
This could be among the underlying mechanisms of the association between diabetes and COVID-19. Another devastating event which takes place in addition to the direct viral effects and inflammatory and immune factors, the down regulation of ACE2 and imbalance between the RAS and ACE2/angiotensin-(1–7)/MAS axis may also contribute to the multiple organ injuries in COVID-19 patients.
Implications of COVID19 on comorbid patients
The comorbid patients have complex etiologies which are driven by the unrelated causes such as unhealthy lifestyles, ageing or obesity or even due to environmental or climate change. In such cases there are huge possibilities of apparent high blood pressure , increase in blood glucose levels, elevated blood lipids and may be representations of deep lying lifestyle habits.
A systematic review and meta-analysis was conducted to evaluate comorbidities associated with severe and fatal cases of COVID-19. Thus, it is obvious that there are a number of multiple risk factors that contribute to the development of NCDs.
The various types of risks can be divided into three primary risk sets: modifiable behavioural risk factors, non-modifiable risk factors and metabolic risk factors, many of which are common for several diseases. The thought remains whether diabetes mellitus patients or hypertensive patients are at increased risk for COVID19 in this era of pandemic.
The author is Assistant Professor, Department of Zoology, Central University of Kashmir
Disclaimer: The views and opinions expressed in this article are the personal opinions of the author.
The facts, analysis, assumptions and perspective appearing in the article do not reflect the views of GK.