Expert doctors in infectious disease and lung health speak to the transmissibility of walking pneumonia and more infection facts.
What Is Walking Pneumonia and How Contagious Is It? Expert Doctors Reveal
Published on Mar. 13, 2025
About the experts
- Linda Yancey, MD, is a board-certified physician in infectious disease and internal medicine with over two decades of experience practicing in Texas. She completed her residency at Mayo Clinic in Scottsdale, Arizona, and pursued a fellowship at Baylor College of Medicine in Houston. Currently, Dr. Yancey serves as an infectious disease specialist at Memorial Hermann Hospital in Houston.
- David Janz, MD, MS is a board-certified physician in internal medicine, pulmonary medicine, and critical care. He serves as the Director of Medical Critical Care Services at University Medical Center in New Orleans. Dr. Janz earned his medical degree from Louisiana State University (LSU) School of Medicine and went on to complete his residency in internal medicine, followed by a fellowship in pulmonary and critical care at Vanderbilt University in Nashville, Tennessee. He also holds a Master of Science in Clinical Investigation from Vanderbilt.
Highlights
- Walking pneumonia is a milder form of regular pneumonia.
- It can be contagious when caused by specific bacteria or viruses.
- Those at higher risk include the elderly, young children, and those with weakened immune systems.
- Prevention includes vaccination, good hygiene practices, and wearing a mask while sick.
According to the Centers for Disease Control and Prevention (CDC), Mycoplasma pneumoniae (M. pneumoniae)—one of the bacteria responsible for walking pneumonia—causes an estimated 2 million infections in the United States each year. However, many cases go undiagnosed, meaning the actual number is likely much higher. Between 2024 and 2025, Mycoplasma pneumoniae infections have been on the rise, making it more important than ever to understand how contagious walking pneumonia really is.
Pneumonia itself is an infection that affects the lungs. We breathe in and out constantly, and “sometimes that air contains bacteria or viruses that can cause infection of the lungs,” explains Linda Yancey, MD, a board-certified infectious disease physician at Memorial Hermann Hospital in Houston. While traditional pneumonia can cause severe illness, walking pneumonia is a milder form that often allows people to go about their daily routines despite the infection.
Ahead, Dr. Yancey and David Janz, MD, a board-certified pulmonologist and critical care specialist, answer key questions about walking pneumonia, including how contagious it is, who’s most at risk, and when to see a doctor.
What is walking pneumonia?
Dr. Janz explains that walking pneumonia, also known as atypical pneumonia, is a form of pneumonia just like any other infectious type. “A bacteria, virus, or fungus makes its way to the outer regions of the lungs and causes an infection that can be seen on an x-ray of the lungs and makes us feel ill.”
However, walking pneumonia stands apart from other types of pneumonia due to its unique causes, often involving less common organisms, and a more gradual onset of symptoms.
Walking pneumonia tends to follow seasonal trends, particularly when viruses like influenza and respiratory syncytial virus (RSV) are to blame. “These are more commonly seen in the winter months,” Dr. Janz adds.
What’s the difference between walking pneumonia and regular pneumonia?
Walking pneumonia gets its name, in part, because it differs from regular pneumonia in severity. The term refers to a milder respiratory infection that develops gradually over several days, often lingering for weeks or even months. Symptoms—such as a persistent cough and mild breathing difficulties—are less intense, “allowing the patient to still be ‘walking’ while having a pneumonia,” explains Dr. Janz.
Another key difference lies in the types of organisms responsible for each condition. Walking pneumonia is most commonly caused by bacteria such as Mycoplasma pneumoniae, Chlamydophila pneumoniae, or Legionella pneumophila. In contrast, regular pneumonia is often triggered by bacteria like Streptococcus pneumoniae or Haemophilus influenzae, as well as certain viruses or fungi.
Most cases of pneumonia are mild and don’t require hospitalization. “But all pneumonia exists on a spectrum—the most severe cases are thankfully also the rarest,” says Dr. Yancey.
Symptoms of walking pneumonia
While walking pneumonia is generally milder than other forms of pneumonia, its symptoms can linger longer. According to both doctors, the most common signs to watch for include:
- Persistent cough
- Sputum production (mucus from the lungs)
- Difficulty breathing
- Chest pain
- Fever
How contagious is walking pneumonia?
“Walking pneumonia can be contagious, especially if it is caused by a virus, such as influenza or RSV, or bacterial organisms such as Chlamydia pneumoniae or Mycoplasma pneumoniae,” says Dr. Janz. While there isn’t an exact duration of contagiousness, Dr. Janz advises, “Anyone with a fever should be considered infectious.”
Who’s most at risk for catching walking pneumonia?
Certain groups of people are more vulnerable to walking pneumonia than others. “The very old and the very young, and anyone with a compromised immune system,” says Dr. Yancey. Because these individuals are more susceptible to infections, it’s best to avoid close contact with newborns, the elderly, or those undergoing chemotherapy if you’re feeling unwell.
The Cleveland Clinic shares that certain medical conditions, lifestyle habits, and living environments can also increase the risk of developing walking pneumonia. These include:
- Asthma
- Chronic obstructive pulmonary disease (COPD)
- Emphysema
- A history of tobacco use
- Regular use of inhaled corticosteroids
- Frequent exposure to crowded settings such as nursing homes, military barracks, schools, or dormitories
How to prevent the spread of walking pneumonia
“Vaccination against influenza and RSV are the best preventative steps for those who qualify for these vaccinations,” explains Dr. Janz. The CDC recommends annual flu shots for everyone six months and older, while the RSV vaccine is advised for adults 60 and older, pregnant individuals, and infants at higher risk of severe illness. (Read Which Vaccines Do You Need in 2024-25? Here Are Experts’ Recommendations for All Ages.)
In addition to vaccination, simple precautions can help reduce the spread of walking pneumonia. “Wearing a mask while sick protects the people around you,” says Dr. Yancey. Practicing good hand hygiene, covering coughs and sneezes, and avoiding close contact with others while contagious can also help keep infections at bay.
How is walking pneumonia treated?
“Antibiotics can treat the bacterial causes of walking pneumonia, and some of the viral causes can be treated with antiviral medicines,” says Dr. Janz. However it’s also important to note that concerns about antibiotic resistance are on the rise, and prevention is most beneficial for the individual and the public.
Treatment may also include steroids to reduce inflammation and supplemental oxygen for those experiencing difficulty breathing, adds Dr. Yancey.
Potential walking pneumonia complications
Walking pneumonia symptoms are often subtle, which is why many people don’t seek medical care. However, in some cases—especially for those at higher risk—it can lead to more serious health issues.
According to the Mayo Clinic, potential complications include:
- A more severe form of pneumonia
- Worsening asthma symptoms
- Encephalitis, a serious brain inflammation
- Hemolytic anemia, a condition that causes excessive red blood cell breakdown
When to see a doctor
Both medical experts recommend seeking medical attention if you experience:
- A cough that lingers for more than a week
- Severe or worsening cough with fever
- Chest pain
- Shortness of breath or difficulty breathing, which may require oxygen
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