While COVID-19 and the flu dominate headlines, a quieter respiratory health crisis is unfolding: dozens of other viruses and bacteria are circulating year-round, causing everything from mild coughs to serious pneumonia. The CDC actively monitors these lesser-known pathogens through emergency departments, hospitals, and labs, but many people don't realize they're at risk. Understanding which respiratory illnesses are spreading now and who's most vulnerable can help you protect yourself and your family .

What Respiratory Pathogens Are Circulating Beyond COVID and Flu?

The CDC tracks a surprising number of respiratory disease-causing organisms that often fly under the radar. These include common human coronaviruses (different from the virus that causes COVID-19), group A streptococcus bacteria, human metapneumovirus (HMPV), mycoplasma pneumoniae, parainfluenza viruses, pneumococcal disease, and adenoviruses. Each has its own seasonal pattern, severity level, and vulnerable populations .

Human coronaviruses, for example, typically cause mild to moderate upper respiratory tract illnesses similar to the common cold, but they can progress to pneumonia or bronchitis in certain groups. These viruses spread year-round with increased activity in fall and winter. Meanwhile, mycoplasma pneumoniae is a common cause of mild respiratory illness, though it can develop into a more severe condition known as "walking pneumonia." Unlike many respiratory pathogens, mycoplasma infections can occur any time of year but are more common in summer and early fall .

Who Is Most at Risk for Severe Respiratory Illness?

Not everyone faces the same risk when exposed to these pathogens. Certain groups are significantly more vulnerable to developing serious complications. Understanding your risk category can help you take appropriate precautions and seek medical attention promptly if symptoms develop .

• Young Children and Infants: Infants, young children, and school-aged children are at higher risk for severe disease from multiple pathogens including human metapneumovirus, parainfluenza viruses, and pneumococcal disease. These age groups have developing immune systems that haven't yet encountered many respiratory pathogens.
• Older Adults: Adults 65 years and older face increased risk for severe pneumococcal disease, complications from human coronaviruses, and serious infections from group A streptococcus. Age-related immune system changes make this population more vulnerable to bacterial and viral respiratory infections.
• People with Weakened Immune Systems: Individuals with compromised immunity, whether from medical conditions or treatments, are at higher risk for lower respiratory tract infections from human metapneumovirus, parainfluenza viruses, and common human coronaviruses. This group includes people with cardiopulmonary disease and those taking immunosuppressive medications.
• People with Chronic Lung Conditions: Those with asthma or chronic obstructive pulmonary disease (COPD) face particular danger from human metapneumovirus, which can exacerbate their underlying conditions and lead to more severe illness.

How to Protect Yourself From Respiratory Illness

While you can't avoid all respiratory pathogens, evidence-based prevention strategies can significantly reduce your risk of infection and transmission to others. The CDC recommends a multi-layered approach tailored to different pathogens .

• Practice Good Hand Hygiene: Wash your hands frequently with soap and water, especially after touching your face, before eating, and after being in public spaces. Hand hygiene is effective against most respiratory bacteria and viruses, including group A streptococcus, mycoplasma pneumoniae, and parainfluenza viruses.
• Cover Coughs and Sneezes: Use a tissue or your elbow, not your hands, when coughing or sneezing. This prevents respiratory droplets from spreading to others and is particularly important if you're around vulnerable populations like young children or older adults.
• Take Steps for Cleaner Air: Improve indoor air quality through ventilation, air filtration, or spending time outdoors when possible. Better air quality reduces the concentration of respiratory pathogens in shared spaces and lowers transmission risk.
• Get Vaccinated: Pneumococcal vaccination is the most effective way to prevent pneumococcal disease. The CDC recommends pneumococcal vaccination for all children younger than 5 years old, people 5 through 49 years old with certain risk conditions, and all adults 50 years or older.
• Use Precautions When Sick: If you're experiencing respiratory symptoms, stay home when possible, wear a mask around others, and maintain distance from vulnerable individuals. This prevents spreading pathogens to people at higher risk for severe disease.

What Should You Know About Specific Respiratory Pathogens?

Different pathogens have distinct characteristics that affect how they spread and who they harm most. Group A streptococcus, for instance, is the bacteria that causes "strep throat," which is usually minor but can rarely result in serious infections like toxic shock syndrome. Respiratory infections from group A strep can occur year-round but are more common in winter and early spring. Healthcare providers can test for the presence of this bacteria and treat it with antibiotics if needed. In severe cases, surgery may be needed to remove infected tissue .

Human metapneumovirus presents a different profile. It causes symptoms including cough, fever, nasal congestion, and shortness of breath, and clinical symptoms may progress to bronchitis or pneumonia. HMPV season typically begins in winter and lasts through spring. Young children, older adults, and people with weakened immune systems are at higher risk for lower respiratory tract infections from HMPV, including bronchitis, bronchiolitis, and pneumonia. The virus can also exacerbate asthma and COPD in people who already have these conditions .

Parainfluenza viruses are another concern, with four different types (HPIV-1 through HPIV-4) that have varying seasonal patterns. HPIV-1 and HPIV-2 peak in the fall, often in alternating years, and are most often associated with croup, an infection of the vocal cords and windpipe. HPIV-3 usually peaks every year in spring and early summer and is more often associated with bronchiolitis, bronchitis, and pneumonia. HPIV-4 appears to occur in fall and winter but has less defined seasonal patterns. Most parainfluenza illnesses are mild and typically only require treatment of symptoms .

"Respiratory health supports your breathing and addresses disorders and injuries involving the lungs and airways. Asthma, COPD, lung cancer, pneumonia, and other respiratory conditions can cause a range of symptoms that affect breathing," explained Rohan Mankikar, MD, chief of pulmonary medicine at Huntington Hospital.

Rohan Mankikar, MD, Chief of Pulmonary Medicine at Huntington Hospital

When Should You Seek Medical Attention?

While most respiratory infections resolve on their own, certain symptoms warrant professional evaluation. A chronic cough, breathlessness, chest pain, excess mucus, wheezing, or coughing up blood may indicate a respiratory condition that needs medical attention. Seeing a doctor about these symptoms before they become severe can help you treat lung diseases before they become serious or life-threatening .

For mycoplasma pneumoniae specifically, most mild infections resolve without medicine, but healthcare providers may treat pneumonia with antibiotics. Similarly, pneumococcal disease requires antibiotic treatment, and in severe cases, surgery may be needed to remove infected tissue .

The key takeaway is that respiratory health extends far beyond the well-known threats of COVID-19 and influenza. By understanding which pathogens are circulating, recognizing your personal risk factors, and following evidence-based prevention strategies, you can significantly reduce your chances of serious respiratory illness. If you develop concerning symptoms, don't wait; contact your healthcare provider promptly for evaluation and guidance.