Coronavirus and the Immune System

Changes as You Age

Who gets COVID-19 and why? Why does a 104-year-old man survive his infection, a 25-year-old female athlete training for a 10K become infected and a 52-year-old man dies from it? This is what we know right now. It is not complete, but this is an ever-evolving learning curve, nothing new in medical science.

The amount of virus needed to make you sick is called the Infectious Dose. Populations without a significant immunity are particularly susceptible to low-infectious doses. Since coronavirus is a novel infection, no one has a remembered immunity. SARS-CoV-2 is the virus that causes COVID-19. The minimum infectious dose is not known at this time but is suspected to be low because of the ease it spreads through casual interpersonal contact. Viral Load is the measurement of the amount of virus particles. It is the amount of virus present in an infected person that has had time for cell replication to occur. It follows that a high infectious dose leads to a higher viral load. As with most viruses the higher the viral load, the higher the severity of symptoms in an individual. These same people are more contagious because they shed more whole virus. This is an especially important point for healthcare professionals who are caring for infected patients. The more viral particles you inhale into your lungs, the higher your risk of infection and the higher your potential for damage is.

Immunosenescence is the term for the decline in your immune system as you age. But what else contributes to your immune system strength besides age? We know what is supposed to occur. An intruder (virus) breaks in, the home security (immunity) comes on and rallies law enforcement (white blood cells) to arrest it and lock it up for good. With a novel virus such that we are faced with now, this scenario has changed. Mercifully, the world experiences pandemic relatively rarely but perhaps we can use this experience to better explore the nature of the body’s immune system and factors affecting it.

As we age, we produce fewer cells overall including the B and T cells that are the immune systems law enforcement mechanisms. In particular, the T-cells of which we have 2 types:

  • Memory Cells that have seen this pathogen before and remember how to combat it.
  • Naïve Cells that have never seen anything exactly like this before and must start from scratch to learn how to fight this off.

SARS-CoV-2 is causing COVID-19 and we have no memory cells to call for backup and because of immunosenescence, even fewer naive cells to deploy making most of the older population (over 60) vulnerable. But not all of them! The other enigma is that no one really has a handle on what a healthy amount of B and T-cells looks like. We know that bone marrow produces the white blood cells that make up B and T-cells so is that the root of the problem? Genetics? Lifestyle?

Inflammation is a vital part of the immune system’s response to injury and infection. It is the body’s way of signaling the immune system to heal and repair damaged tissue, as well as defend itself against foreign invaders, such as viruses and bacteria. Inflammation is meant to be short term in duration. Inflammaging is chronic low-grade inflammation that develops as people age. It keeps the body on high alert and causes damage and aging on a cellular level contributing to Alzheimer’s, heart disease and type-2 diabetes to name a few. Inflammaging is silent but deadly as it produces little to no symptoms of its own, so your immune system is in trouble without knowing about it and is a factor in vulnerability to disease of infection.

Weight, lack of sleep, diet and stress are all factors in inflammation so what can we do to support our immune system? AARP makes several suggestions:

  • Move! Exercise boosts your immunity and lowers inflammation. A 2019 study in Nature Reviews: Immunology called skeletal muscle a major immune regulatory organ and that higher intensity workouts (HIIT-High Intensity Interval Training) can lower immunosenscence.
  • Weight: Obesity equals inflammation. Maintaining a healthy weight is a major factor in decreasing inflammation. Belly fat as a metabolically active tissue, can trigger weight gain.
  • Know Your Normal: Knowing this makes you aware when something is off. Stay on top of chronic conditions so you can report accurately to healthcare professionals. Digital monitoring can be extremely helpful here.
  • Nutrition: Eating right plays a key role in the immune system by providing the proper building blocks (protein and fiber) for the good bacteria necessary to fight inflammation.
  • Calm: Anti-stress self-care are not as measurable as exercise or weight but are just as important to overall health. It is not your job to control or manage everything so let it rest.
  • Vaccines and Medications: Stay current with your vaccines and take your medications how and when prescribed. Discuss with your healthcare professional ways to counter any inflammatory causing medications.

The vast majority of infected people only suffer mild symptoms if at all and most recover completely. Very few children are affected. Most who get sick have underlying vulnerabilities. Some people develop antibodies faster than others leading to speculation that there is a difference in their respiratory microbiome, the collection of bacteria and fungi normal in the respiratory tract that affects how much of the virus enters your lungs. This viral load, the amount a person takes on board all at once may explain why Dr. Li Wenliang, the 31-year-old Chinese physician who first reported COVID-19, died from it. Is it genetic predisposition or a combination of one or more of these factors?  COVID-19 may actually be doing humanity a (questionable) favor in teaching us all what our health and immunity vulnerabilities are and ushering in a new era of immunology research. We are all certainly more aware.

NHS Solutions has Interim Nurse Leaders on the front lines fighting this virus. Reports vary from across the US and methodology for counting things like infection rate, death rate etc. have been purposely removed from this post. The numbers are changing every day and require analysis, consistency and continued study. We welcome your comments.

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