- Across the world, the novel coronavirus has killed elderly people the most, especially those with pre-existing medical conditions such as heart disease. According to the US Centre for Disease Control (CDC), the fatality rate from COVID-19 is highest among those aged 85 or older.
What makes the elderly especially vulnerable to the virus?
- In a letter to the editor addressed to the Journal of Travel Medicine, James Diaz, a professor at Louisiana State University’s School of Public Health, has hypothesised that the reason could lie in the victims’ medications, when they suffer from comorbidities such as cardiovascular diseases, hypertension, diabetes and chronic kidney disease.
What has Diaz claimed?
- For patients with cardiovascular diseases such as refractory hypertension, coronary artery disease and heart failure, some highly recommended medications are angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers (ARBs). These medications are also recommended for the management of cardiovascular disease in elderly patients and in those with diabetes and renal insufficiency.
- When tested on animal models, it was found that the administration of intravenous injections of ACEIs and ARBs increases the ACE2 receptors in their cardiopulmonary circulations.
What does this mean when the findings are applied to humans?
- The ACE2 receptors bind with the proteins present on the exterior of coronaviruses such as SARS CoV and SARS-CoV-2. Significantly, the presence of “S” proteins on the exterior of the SARS-CoV-2 binds with the ACE2 receptors in the lower respiratory tract of COVID-19 patients. When the virus is able to bind with the ACE2 receptors, it can make its way to the patient’s lungs more easily, leading to the possibility of the patient developing pneumonia and potential respiratory failure.
- Citing a descriptive analysis of 1,099 COVID-19 patients treated in China between December 11, 2019 and January 29, 2020, Diaz says that among these, the patients with hypertension, diabetes, coronary artery disease and renal disease suffered more severe outcomes. These included ICU admissions, mechanical ventilation and death.
- Moreover, all the patients with the aforementioned diagnoses were using ACEIs and ARBs, which may mean that these medications are a possible risk factor for severe disease outcomes in the case of COVID-19.
- Diaz points out that elderly patients with such comorbidities are more likely to be taking these medications, and therefore, are at greater risk of facing fatal outcomes.
- Significantly, one reason that children may be better protected against developing severe symptoms could be that they have fewer ACE2 receptors in their lower respiratory tracts, making it more difficult for the coronavirus proteins to bind and find their way to the lungs.
- “These immunological and molecular observations support the clinical observations of infrequent COVID-19 infections in children compared to more frequent COVID-19 infections in elderly patients, especially those with comorbid conditions,” Diaz notes.