Respiratory infections are a major health concern and are divided into upper and lower respiratory tract infections. Upper respiratory tract infections are mostly viral and self-limiting; billions of cases occur globally each year. Lower respiratory tract infections such as pneumonia and bronchitis can cause significant illness, especially in children, older adults, and individuals with comorbidities or immunocompromise. In 2021, lower respiratory tract infections caused more than 2 million deaths globally, mainly in low- and middle-income countries. Preventive measures include hand hygiene, masks, ventilation, vaccination, and pharmacologic prophylaxis. Vaccines for influenza, COVID-19, and respiratory syncytial virus infection are available in the United States. Vaccines for human metapneumovirus, parainfluenza viruses, and human rhinovirus are in development. Differentiating viral from bacterial infections is challenging. Biomarkers such as procalcitonin and C-reactive protein can guide antibiotic use. Treatment of viral respiratory infections is mainly supportive, with use of intranasal decongestants and nonsteroidal anti-inflammatory drugs. Early use of zinc and vitamin C may shorten symptom duration; evidence for vitamin D, probiotics, and echinacea varies. Judicious antibiotic use prevents antimicrobial resistance, and treatment with no or delayed antibiotics is often sufficient. Most viral respiratory infections resolve in 1 to 2 weeks, although coughing may persist longer. Patient education about self-care, prevention, and antibiotic use is key to better outcomes and reduced health care burden.
Naik H. Viral Respiratory Infections: Upper and Lower Respiratory Tract Infections. FP Essent. 2026;569:7-14.
Case 1. CW is a 56-year-old man with a 10-pack-year smoking history who presents with 4 days of sore throat, nasal and chest congestion, productive cough, myalgia, and malaise. He has fever, dyspnea, and chest pain. He reports minimal relief with ibuprofen and pseudoephedrine. Vital signs are normal. His lungs are clear on auscultation, but bronchial breath sounds are heard throughout. He reports a history of bronchitis 2 years ago and asks whether he needs an antibiotic for this current infection.
Respiratory infections are common and are generally divided into upper respiratory tract infections (URTIs) and lower respiratory tract infections (LRTIs). URTIs affect the nose, sinuses, pharynx, larynx, and middle ear. They include colds, pharyngitis, otitis media, and sinusitis. LRTIs affect the airways and lungs and include bronchitis, bronchiolitis, and pneumonia.1 URTIs are generally viral and self-limited, whereas LRTIs vary in severity and can cause significant morbidity and mortality, particularly in children, older adults, and those with comorbidities.2
Epidemiology
Globally, approximately 17.2 billion URTI cases occur each year. These infections constitute the majority of respiratory infection cases, with the US population averaging more than three per year.3 URTIs cause fewer deaths than LRTIs, but their high occurrence rate makes them the leading cause of outpatient visits and missed work and school.2
LRTIs are the leading cause of infectious disease mortality in the United States, accounting for approximately 78.8% of infectious disease deaths.3 Worldwide, pneumonia accounts for 14% of deaths in children younger than 5 years.4 In 2019, this amounted to approximately 740,000 deaths, most of which occurred in low- and middle-income countries.4 Although LRTI mortality has declined in the past 30 years due to vaccination, better nutrition, and improved health care, the burden persists.5
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