critically ill man getting oxygen in hospital

What Coronavirus Does To The Body — And Why Some People Are Sicker Than Others

Everyone is using words like “unprecedented” and “unknown” when talking about coronavirus and COVID-19. These aren’t just buzzwords — they are some of the only descriptors that most of the scientific community agree on.

That’s because so much of the science behind COVID-19 is up in the air. Since this is a brand new virus, there hasn’t been enough time for studies that show the exact nature of the virus, or why some people die from the virus while others never even cough.

However, despite the unknowns, there are a few things that are generally accepted as truth, such as how it’s spread, what it does to the inside of the body, and several of the risk factors that make people susceptible to severe illness.

Coronavirus Comes In: The Body’s Response

coronavirus transmission graphic

The virus can also be spread through contact with contaminated surfaces or objects, such as railings, countertops, or elevator buttons. If respiratory droplets land on these surfaces and someone touches them, and then touches their mouth, nose, or even eyes, they can become infected.

Once the virus is in the body, it goes on the attack (even though you might not experience symptoms for several days or not at all). It starts by damaging the part of the body through which it entered. For example, if it came in through your nose, you might experience a runny nose or nasal congestion, much like a typical upper respiratory infection.

In about 80% of cases, the immune system gets the job done at this point. Symptoms are mild to moderate, and most people can generally recover at home (although it might not always be pleasant). But in other cases, the immune system can’t fight off the virus, and the virus makes its way down to the lower respiratory tract. That’s when the virus can become more severe.

When Coronavirus Enters The Respiratory Tract

Coronavirus seems to prefer growing in the lower respiratory tract. The virus cells replicate and cause more severe respiratory problems, such as bronchitis or pneumonia.

Pneumonia can be particularly dangerous. The immune system kicks into high gear to fight the virus and stop it from damaging cells in the lungs, but this comes with some collateral damage The linings of these cells thicken and restrict the lungs, making it difficult for the body to pump oxygen throughout the bloodstream.

Still, the immune system is powerful and can eventually fight off the virus. But if the virus wins, the lungs might not be able to supply enough oxygen to organs like the kidneys, liver, or brain. If this is the case, the organs can completely shut down — bringing the virus from severe to life-threatening.

Even in these cases, there is room for some hope. Some patients respond well to ventilators, which take over the lungs’ function and allow the body to rest. This may be able give the body the strength it needs to restore lung function and recover.

We Know Why Certain Populations Are High-Risk

One of the biggest unknowns is why some people are able to have those mild and moderate cases, while others end up fighting for their life.

We do know that two of the major risk factors for having a severe case are older age and certain underlying health conditions.

Older Adults

The immune system weakens with age, putting adults ages 65 and older at higher risk. The risk increases even more, with the highest risk of death being in patients ages 85 and older. And, older adults tend to have other chronic conditions that are, themselves, risk factors.

Older adults may also be more at risk because many live in nursing homes or long-term care facilities, where the virus is known to spread.

Underlying Medical Conditions

In patients of all ages, certain underlying medical conditions can be risk factors for severe illness or death from COVID-19.

These conditions may include:

  • Moderate to severe asthma
  • Chronic lung disease, such as cystic fibrosis or chronic obstructive pulmonary disease (COPD)
  • Diabetes
  • Serious heart conditions, such as congenital heart disease or pulmonary hypertension
  • Liver disease
  • Chronic kidney disease being treated with dialysis
  • Severe obesity

It works both ways — COVID-19 can make these conditions worse and the conditions can make it more difficult for the body to fight the virus.

COVID-19 is especially dangerous for people who may be immunocompromised (have a weakened immune system), such as those receiving cancer treatment, have had an organ or bone marrow transplant, or have untreated HIV. Their immune system is already in overdrive and cannot afford to have to work even harder.


It makes sense that older adults and people with certain medical conditions are considered high-risk. But what’s leaving the medical community particularly confused is why younger or otherwise healthy people can still experience major, and even fatal, complications.

Low Risk But Severe Illness: A Few Theories

Biological Risk Factors

  • Genes: There is a possibility that variations in some genes could make it easier for the virus to get into the lungs
  • Lack of surfactant: Surfactant is an ingredient produced by the body that keeps the lungs pliable and soft. If the body doesn’t make enough of it, the lungs can stiffen and have difficulty squeezing and pumping.
  • A very strong immune system: Opposite of being immunosuppressed, people with very reactive immune systems might actually fight so hard that they overwhelm the lungs and other organs. In fact, some researchers believe that this is why younger people with COVID-19 are dying of strokes.

Lifestyle Risk Factors

  • Risk perception: Many younger people or healthy adults don’t believe that they are susceptible to the disease and are more lax about social distancing or rigorous handwashing.
  • Smoking: Cigarette smokers may have diminished lung function, which can make them more susceptible to respiratory illnesses (like pneumonia). While more research is needed, early studies have shown a link between smokers and negative outcomes of the virus.
  • Vaping: Vaping is a major problem in the younger population, with many teens and young adults mistakenly believing that it’s not as bad as smoking cigarettes. However, vaping can cause lung damage, too, and lead to increased susceptibility for respiratory illnesses.

How The Virus Is Impacting The Black Community

Coronavirus doesn’t care if you are white or black or Hispanic. There is no biological reason why the virus would attack one race over another. Yet that doesn’t mean that it’s affecting everyone equally. While COVID-19 is devastating for any community, it’s been especially so in the black community.

Look at Milwaukee County, for example. Almost three-quarters of the people who have died from the virus are black, but only a quarter of the county’s population is black. Other US cities have noticed similar trends where the virus affects and kills the black community disproportionately.

There are a few reasons why this might be happening, including:

  • Black Americans have higher rates of underlying medical conditions that worsen the impact of the virus, such as lung disease or diabetes. They also tend to have less access to care, which makes treating both the underlying condition and the virus more difficult.
  • “Essential jobs,” such as those in the food service or hotel industries, are often held by black Americans. They are still reporting to work, which can mean putting themselves in close contact with others and higher risk for contracting the virus.
  • Housing disparities may also play a role. Black children have higher asthma rates because they’re more likely to live in older homes or in segregated areas near busy highways (where they’re exposed to pollutants) — and asthma can make COVID-19 more dangerous. Also, black families are more likely to live in densely-populated areas, and the virus can spread easily in these types of neighborhoods.

Unknowns Are Growing — But So Are The Knowns

New symptoms seem to sprout up. Populations that shouldn’t be high-risk are getting severely sick. It seems like the unknowns just keep adding up.

But even so, knowledge about COVID-19 is also growing. Every day, scientists are one step closer to uncovering more information and to developing a vaccine. We’ll keep you updated as they do.

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