It is likely that the American population now collectively knows more about coronaviruses than any other pathogen: HPV, E. coli, herpes, or even HIV. Coronaviruses (CoV) are the largest known RNA viruses and they infect many species besides humans. Like COVID-19, both the SARS CoV epidemic (2002-03) and MERS CoV epidemic (2012) emerged from bat-to-human transmission in China, but each epidemic recorded far greater mortality rates: 10% and 36%, respectively.
For weeks, “viral pneumonia” has been the verbiage used to characterize severe COVID-19 illness. It’s an easy-to-understand concept, given that coronavirus infections most often attack the respiratory system. In reality, neither life nor disease is ever that simple.
When you think of pneumonia, it’s usually bacterial pneumonia. Most folks imagine germs in the lung causing a lot of inflammation and tissue damage. Administering the correct antibiotic kills the invading bacteria and the body heals. In the COVID-19 scenario, the presence of those spiky viruses inside lung cells ignites an explosive cascade of chemical events throughout the body. Scientists refer to this as a “cytokine storm.”
The healthy immune response is a highly organized, richly choreographed sequence of biological events involving chemical signals, inflammatory cells, and targeted organs that is designed to swiftly eliminate threats to the host — threats like an unfamiliar virus. Powerful proteins called cytokines direct the traffic as it relates to coordinating the body’s response to infection.
For most individuals infected with SARS-CoV-2, the virus responsible for COVID-19 disease, the immune apparatus works exactly as intended with a predictable recovery. In fact, it appears that host immunity works so well that many infected people experience no symptoms whatsoever.
The remainder encounter some form of severe COVID-19 illness with chest pain or pressure, severe shortness of breath, stubborn fever, and a persistent dry cough. Researchers believe most of these individuals mount an overenthusiastic, confusing, hyper-inflammatory response. Think fire in a large and crowded dance club.
Here’s what happens. Coronaviruses mute the ability of some inflammatory cells to release necessary antiviral cytokines like interferon. Yet at the same time, CoVs stimulate overexpression of pro-inflammatory cytokines — proteins with names like TNF, IL-6, and CCL3. This resultant dysregulation leads to the cytokine storm.
It’s as if both the choreographer and orchestra leader each just suffered a stroke on opening night at the ballet. The performers and musicians are unsure what to do and chaos ensues before a paralyzed audience. The lung tissue is flooded with molecules that cause blood vessels to leak, fluid to accumulate, and healthy cells to quickly die in the process. Of course, the lungs are supposed to be working 24/7 to provide fresh oxygen for the rest of our body, but that task is derailed while trying to survive the cytokine storm.
Heroic ICU workers have no antiviral medication to suppress the virus. They focus instead on providing respiratory support with supplemental oxygen, and if necessary, mechanical ventilation. Keeping one adult on a ventilator requires constant monitoring and bedside care by four or more healthcare team members. Comprehending the staffing and logistical requirements is overwhelming.
Our understanding of the risk factors for developing severe COVID-19 illness has greatly expanded recently. The elderly have weaker immunity, and like others with an established immunodeficiency, cytokine dysregulation is never far away. Chronic smokers have been added to the list because of their vulnerable lungs and because their entire bodies are in a perpetual state of smoldering inflammation. Finally, those who are obese (defined as a BMI greater than 30, which makes up nearly 40% of U.S. adults) are also at greater risk to confront the cytokine storm because deep, visceral fat constantly triggers inflammatory signals.
Is there a COVID-19 silver lining? Sheltering-at-home may be just the opportunity people need to intensely focus on enacting positive lifestyle choices like smoking cessation and healthy weight loss. A busy life can create obstacles and generate plausible excuses, thus sabotaging wellness goals. Maybe there is sufficient time now to get started. Could there ever be a better time to embrace a healthier life?
Doctor Lloyd is a licensed physician and a board-certified surgeon and pathologist. As Health Director for Transamerica Advanced Markets, he provides valuable medical expertise for Transamerica’s Wealth + HealthSMthought leadership initiative.
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