What Does COVID-19 Do to Your Lungs?

COVID-19 is a respiratory disease, one that especially reaches into your respiratory tract, which includes your lungs.

COVID-19 can cause a range of breathing problems, from mild to critical. Older adults and people who have other health conditions like heart disease, cancer, and diabetes may have more serious symptoms.

Here’s what the new coronavirus does to your lungs.

Coronavirus and Your Lungs

SARS-CoV-2, the virus that causes COVID-19, is part of the coronavirus family.

When the virus gets in your body, it comes into contact with the mucous membranes that line your nose, mouth, and eyes. The virus enters a healthy cell and uses the cell to make new virus parts. It multiplies, and the new viruses infect nearby cells.

Think of your respiratory tract as an upside-down tree. The trunk is your trachea, or windpipe. It splits into smaller and smaller branches in your lungs. At the end of each branch are tiny air sacs called alveoli. This is where oxygen goes into your blood and carbon dioxide comes out.

The new coronavirus can infect the upper or lower part of your respiratory tract. It travels down your airways. The lining can become irritated and inflamed. In some cases, the infection can reach all the way down into your alveoli.

COVID-19 is a new condition, and scientists are learning more every day about what it can do to your lungs. They believe that the effects on your body are similar to those of two other coronavirus diseases, severe acute respiratory syndrome (SARS) and Middle East respiratory syndrome (MERS).

Mild and Moderate Cases

As the infection travels your respiratory tract, your immune system fights back. Your lungs and airways swell and become inflamed. This can start in one part of your lung and spread.

About 80% of people who have COVID-19 get mild to moderate symptoms. You may have a dry cough or a sore throat. Some people have pneumonia, a lung infection in which the alveoli are inflamed.

Doctors can see signs of respiratory inflammation on a chest X-ray or CT scan. On a chest CT, they may see something they call “ground-glass opacity” because it looks like the frosted glass on a shower door.

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Severe Cases

About 14% of COVID-19 cases are severe, with an infection that affects both lungs. As the swelling gets worse, your lungs fill with fluid and debris.

You might also have more serious pneumonia. The air sacs fill with mucus, fluid, and other cells that are trying to fight the infection. This can make it harder for your body to take in oxygen. You may have trouble breathing or feel short of breath. You may also breathe faster.

If your doctor takes a CT scan of your chest, the opaque spots in your lungs look like they start to connect to each other.

Critical Cases

In critical COVID-19 -- about 5% of total cases -- the infection can damage the walls and linings of the air sacs in your lungs. As your body tries to fight it, your lungs become more inflamed and fill with fluid. This can make it harder for them to swap oxygen and carbon dioxide.

You might have severe pneumonia or acute respiratory distress syndrome (ARDS). In the most critical cases, your lungs need help from a machine called a ventilator to do their job.

There’s evidence that 20-30% of the critically ill patients can develop clots in the lungs, heart, brain and legs, some of which are life threatening.

A few people have needed lung transplants because of severe tissue damage from COVID-19.

COVID-19 Complications

It can take time to feel better after you have pneumonia. You may feel more tired than usual for a while. You might also find that you can’t exercise like you used to.

Some people had a cough even after they recovered from COVID-19. Others had scarring in their lungs. Doctors are still studying whether these effects are permanent or might heal over time.

WebMD Medical Reference Reviewed by Neha Pathak, MD on September 23, 2020

Sources

SOURCES:

The Lancet Infectious Disease: “Radiological findings from 81 patients with COVID-19 pneumonia in Wuhan, China: a descriptive study.”

National Cancer Institute: “NCI Dictionary of Cancer Terms - alveoli.”

Biophysical Journal: “How Viruses Invade Cells.”

Johns Hopkins Medicine: “Coronavirus COVID-19 (SARS-CoV-2).”

The Lancet Respiratory Medicine: “Pathological findings of COVID-19 associated with acute respiratory distress syndrome.”

World Health Organization: “Report of the WHO-China Joint Mission on Coronavirus Disease 2019 (COVID-19),” “Q&A on coronaviruses (COVID-19).”

The Lancet: “COVID-19: What is next for public health?” “Clinical course and risk factors for mortality of adult inpatients with COVID-19 in Wuhan, China: a retrospective cohort study.”

Cleveland Clinic: “Pneumonia.”

UpToDate: “Patient education: Acute respiratory distress syndrome (The Basics),” “Coronavirus disease 2019 (COVID-19).”

American Lung Association: “Pneumonia Treatment and Recovery.”

American Thoracic Society: “What is Pneumonia?”

Radiology: “Time Course of Lung Changes On Chest CT During Recovery From 2019 Novel Coronavirus (COVID-19) Pneumonia,” “Chest CT Findings in Coronavirus Disease-19 (COVID-19): Relationship to Duration of Infection.”

Translational Lung Cancer Research: “Ground-glass nodules of the lung in never-smokers and smokers: clinical and genetic insights.”

News release, University of Florida Health.

News release, Northwestern Medicine.

F.A. Klok, M.J.H.A. Kruip, N.J.M. van der Meer, M.S. Arbous, D.A.M.P.J. Gommers, K.M. Kant, F.H.J. Kaptein, J. van Paassen, M.A.M. Stals, M.V. Huisman, H. Endeman: Incidence of thrombotic complications in critically ill ICU patients with COVID-19, 04.13.2020

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