Upper Respiratory Tract Infections

Children experience an average of two to eight viral upper respiratory infections during the first 2 years of life. Upper respiratory tract infections (URTI), such as the common cold, are usually self-limiting. The major clinical symptoms of URTI include variable degrees of sneezing, nasal congestion, rhinorrhea, cough, low-grade fever, malaise, and headache.

The expected course of illness in young children includes worsening of symptoms through days 2-3 with gradual improvement over 10-14 days. The cough may persist for 3-4 weeks after initial onset of symptoms. View a schematic of the natural history and timing of URTI in this review article (figure 2).

The primary mode of transmission is through infectious droplets that come into contact with mucous membranes (e.g., of the eyes, mouth, or nose) either through inhalation or infected surfaces, fomites, or bodily contact.

Viral Pathogens

Rhinoviruses are the most common pathogens that cause URTIs. More than 100 serotypes are responsible for up to 50% of colds in children and adults. In North America, rhinoviruses are present year-round and peak in September, followed by smaller peaks in March and April. Rhinoviruses are also associated with pharyngitis, acute otitis media, and bronchiolitis or pneumonia.

Several other viruses cause symptoms of the common cold, are associated with specific clinical syndromes, and may involve the lower respiratory tract as well.

• Coronaviruses: Seasonal coronavirus incidence peaks from November to February, causing pneumonia and croup. Coronaviruses include zoonotic and emerging infections such as Middle Eastern respiratory syndrome, severe acute respiratory syndrome, and severe acute respiratory syndrome 2 (SARS-CoV-2).

• Influenza viruses: Incidence peaks during the winter months (with the highest incidence in February). Influenza also can cause lower respiratory tract disease and is often associated with systemic signs of illness (e.g., fever and muscle aches). Influenza can be severe, particularly in children with comorbidities including underlying pulmonary or neurologic diseases. Annual influenza vaccination can protect against severe disease.

• Respiratory syncytial virus (RSV): Infections are typically prevalent during mid-September to mid-April in the United States, with seasonal variations depending on geography. RSV is the most common pathogen that causes bronchiolitis in infants and young children and accounts for 50%-80% of all hospitalizations for bronchiolitis during seasonal epidemics in North America. Most infants who are hospitalized with RSV bronchiolitis are born full-term with no known risk factors, and most infections occur during the first 5 months of life. Preexposure prophylaxis with human monoclonal antibody, palivizumab, is indicated for infants with risk factors for severe RSV infection (e.g., prematurity, cyanotic congenital heart disease, and neuromuscular conditions).

• Human parainfluenza viruses: Incidence peaks from September to January (with the highest incidence in October and November). These viruses, particularly human parainfluenza virus 1, are responsible for most cases of acute laryngotracheobronchitis (croup). Human parainfluenza virus 2 has also been associated with conjunctivitis.

• Adenoviruses: Incidence peaks between September and May. This family of viruses is known to cause pharyngoconjunctival fever (conjunctivitis, watery eyes, pharyngeal erythema).

• Nonpolio enteroviruses (echoviruses, coxsackie viruses): Typically, these viruses circulate year-round, with a distinct peak during the summer months.

• Human metapneumovirus (HMPV): Infections are most common during late winter and early spring and are known to cause pneumonia and bronchitis. The burden of HMPV infection is associated with substantial hospitalizations and outpatient visits among children through age 5 years, and especially during the first year of life.

Bacterial Sinusitis

Acute bacterial sinusitis can be a complication of viral upper respiratory infections or allergic rhinitis. According to the American Academy of Pediatrics and the Infectious Disease Society of America, the diagnosis of acute bacterial sinusitis should be based on strict criteria, including:

• persistent nasal discharge or cough lasting more than 10 days without improvement

• worsening course

• severe-onset concurrent fever and purulent nasal discharge for at least 3 consecutive days

Diagnosis

Most cases of upper respiratory infections can be diagnosed clinically based on the history and physical exam, including questions about exposure to sick contacts with nasal congestion, sore throat, or fever. Laboratory testing to identify the viral pathogen is generally not indicated, unless the patient is being admitted to the hospital for infection control purposes or for the diagnosis of influenza. Testing may be recommended in immunocompromised patients with viral upper respiratory infections because of the risk of rapid progression to lower respiratory disease.

• Rapid antigen testing: Rapid antigen detection tests may be used to identify RSV, influenza viruses, and SARS-CoV-2. The results can be obtained within 15-30 minutes but may have low sensitivity.

• Polymerase chain-reaction (PCR)-based techniques: Currently PCR is the most sensitive and specific testing modality for upper respiratory viruses, especially influenza. Many hospitals have a multiplex PCR assay that is highly specific and can be helpful diagnostically for managing febrile respiratory illnesses in complex patients. Studies have demonstrated that selective use of these tests can reduce antibiotic use in hospitalized patients.

Differential Diagnosis

Upper respiratory infection, or the common cold, in a young child may also mimic several other noninfectious etiologies, including allergic rhinitis, vasomotor rhinitis, or rhinitis medicamentosa (caused by many consecutive days of using nasal decongestant sprays). Similar symptoms can be associated with nasal or inhaled foreign bodies, or with abnormalities in the nose or sinuses. Other infectious etiologies in the differential should include pertussis, bacterial sinusitis, and tonsillitis. Careful history and physical examination are crucial for differentiating the cause.

Management

Supportive care is the mainstay of treatment for uncomplicated URTI. Attention to maintaining adequate hydration and fever reduction are central. Adequate hydration will help thin secretions and soothe the respiratory mucosa. Supportive measures are generally recommended for infants and small children, along with anticipatory guidance for the small risk of complications or persistent symptoms.

In younger infants, topical saline (applied through saline nose drops) followed by removal of secretions through bulb syringe can be performed to assist with clearance of nasal secretions. Saline irrigation (with neti pot or nasal douche) using sterile or bottled water to prevent secondary infection is another option.

Antiviral therapy is not indicated for the viruses mentioned above with the exception of influenza and SARS-CoV-2. See the CDC summary of influenza antiviral medications for infants and children and the CDC guidelines for SARS-CoV-2 for children 12 years and older with risk factors.

Over-the-Counter Medications

• Infants and children aged <6 years: In children within this range, antipyretics and analgesics are generally recommended. Antipyretics (acetaminophen, ibuprofen) can be initiated as needed for infants older than 6 months of age. Other over-the-counter (OTC) medications should be avoided, including nasal decongestants, antihistamines, expectorants, and mucolytic agents. Honey may help with nighttime cough in children older than 1 year (2.5-5 mL straight or diluted in water or juice), but honey should not be given to younger children because of the risk of infant botulism.

• Children aged 6-12 years: Antipyretics and analgesics for symptomatic relief are recommended, and honey may be used for cough. Other OTC medications for treatment of the common cold are not recommended for this age group because no studies have demonstrated benefit as compared with placebo.

• Children aged >12 years: Nasal decongestants (pseudoephedrine, phenylephrine) can provide some symptomatic relief, but monitoring for side effects of these medications (including tachycardia, palpitations, and elevated blood pressure) is important.

Antibiotic Therapy

Most children with upper respiratory infections should not be treated with antibiotic therapy because the etiology is most frequently viral. Antibiotics are overprescribed for upper respiratory infections, leading to adverse effects and complications of antibiotic use as well as contributing to antibiotic resistance. Patients who meet the diagnosis of acute bacterial sinusitis with more than 10 days of symptoms can be observed for 72 hours or started on amoxicillin. If symptoms do not improve by 72 hours of therapy, antibiotic therapy can be modified.

Subsequent Immunity

Several viruses produce lasting immunity, including rhinoviruses, adenoviruses, influenza viruses, and enteroviruses. However, immunity does little to prevent subsequent respiratory tract infections because many serotypes circulate, and viruses may mutate into new variants. RSV and human parainfluenza viruses do not produce lasting immunity and may recur as reinfection, even within the same season. However, this second infection is usually milder and with shorter duration of symptoms. Infections with seasonal coronaviruses and SARS-CoV-2 may result in immunity, however the duration of immunity for SARS-CoV-2 is unknown, although thought to last a minimum of 3-6 months.

Annual immunization against influenza is effective at reducing symptoms, hospitalization, and death. All children aged 6 months and older should receive annual influenza vaccine. Immunizations against SARS-CoV-2 have proven effective; however, boosters have been recommended to address waning immunity and emergence of new variants.