COVID-19 is an upper respiratory illness that spreads as an infected person breathes, speaks, clears their throat, or coughs near others — even if they don't know they're infected.
But what else do we know?
"After gaining entry through either the nose or mouth, the virus travels to the chest and begins to cause injury to the respiratory system," says Dr. Tim Connolly, pulmonologist at Houston Methodist. "The extent of this damage varies from person to person, with some people experiencing only mild damage to the airways. Others, however, suffer damage that's much more severe, which can sometimes even be life-threatening."
Dr. Connolly is here to answer questions you may have about how the new coronavirus affects the lungs, specifically.
Q: What happens to the lungs during a mild case of COVID-19?
Dr. Connolly: Once in the chest, the virus begins to impact a person's airways — causing inflammation. As inflammation increases, a barking, dry cough that sounds and feels like asthma develops. In addition, this can cause chest tightness or deep pain while breathing.
Even though it's generally mild for some people, the swelling and tightness that results from airway inflammation is essentially like having a sprained windpipe. Think of it like having a sprained ankle, but the effects and discomfort that come with having a sprain are felt inside of your chest.
Q: What happens to the lungs during a more severe case of COVID-19?
Dr. Connolly: For some people, the infection becomes more serious and the lung tissue itself becomes swollen and filled with fluid and debris from dead cells — which is clinically referred to as pneumonia.
This fluid build-up can affect a person's oxygen levels, and pneumonia can be mild, moderate, severe or even life-threatening, depending on how impaired gas transfer becomes and how difficult it is to breathe.
If the transfer of oxygen into the blood stream is reduced, a person will often need supplemental oxygen and very close monitoring in a hospital setting.
In very serious cases, a person may need to be placed on ventilator support in the ICU.
Early on during the pandemic, there were a lot of unknowns about how contagious the virus could become during various medical interventions. Time and experience has taught us a lot about this virus, and now we're able to more safely use several noninvasive breathing and oxygen devices, as well as techniques such as prone positioning before we have to resort to full life support with a ventilator.
Q: What does a person with a preexisting lung condition need to know about COVID-19?
Dr. Connolly: A person with pre-existing lung diseases, such as asthma or COPD, generally has less respiratory reserve than a person with no lung issues. Because of this, these individuals are more vulnerable and generally have a harder time if their lungs are impacted by an acute infection.
However, while we initially assumed that people with lung diseases would be disproportionately impacted by this virus, what we're actually seeing in our patient population is that COVID-19 appears to be targeting other groups more consistently — particularly people who are obese, diabetic or have vascular disease such as hypertension.
We still don't fully understand why people with preexisting lung conditions don't make up a larger majority of current COVID-19 cases as initially anticipated. Preliminary data suggest that people with asthma may make less of the receptor that the virus uses to invade the body, called ACE2, making it more difficult for the virus to gain entry into the host. In addition, ongoing maintenance therapy with inhaled steroids, such as budesonide, may also confer an advantage for people with chronic lung conditions.
Q: Does COVID-19 have long-term effects on the lungs?
Dr. Connolly: This new virus has only been around for about six months, so it's much too early to make definitive statements about the potential long-term effects it can have on a person's lungs. In fact, we don't know how this virus affects any organ system in the long run, and this goes equally for the lungs, heart, brain and vascular systems.
In the short-term, an observation that I've made with many of my patients who have recovered from the virus is that a lingering dry cough and fatigue can easily last for many weeks.
Q: Should a person avoid heavy exercise for a while after recovering from COVID-19?
Dr. Connolly: My recommendation about exercise will be markedly different for someone recovering from a rough 72-hour stretch at home versus someone recovering from three weeks of being on a ventilator in the ICU.
That said, most people who have recovered from a mild case over a 10 to 14 day period, and who didn't require hospitalization, still need to assume that their lungs and airways are sprained.
I would avoid resuming heavy exercise until you are symptom-free for at least 7 days. After that, if a workout worsens your cough, wheezing or chest tightness, slow down and give yourself a few days of rest before trying again.
Remember, you can't see the damage, but recovering from a sprained lung is like recovering from a sprained ankle. Go slow.
And one last piece of advice: Regardless of whether you've never had COVID-19, are recovering from COVID-19 or had COVID-19 weeks or months ago, wearing a mask while outside your home is an essential step in keeping yourself and our community safe from COVID-19. We are all in this together and have the power to help stop the pandemic and return life to normal.