What is the recommended treatment for a child with confirmed or suspected human metapneumovirus infection, including management for immunocompromised patients?

Treatment of Human Metapneumovirus (hMPV) Infection in Pediatric Patients

There is no specific antiviral therapy approved for human metapneumovirus infection in children; treatment is entirely supportive care focused on maintaining oxygenation, hydration, and monitoring for respiratory deterioration. 1

Immunocompetent Children

Outpatient Management (Mild Disease)

Antimicrobial therapy is not routinely required for preschool-aged children with viral respiratory infections, as viral pathogens are responsible for the great majority of clinical disease. 2

• Provide supportive care including adequate hydration and fever management 1
• Monitor oxygen saturation by pulse oximetry, especially for children with increased work of breathing or significant respiratory distress 1
• No antibiotics should be prescribed unless there is clear evidence of bacterial co-infection 2

Hospitalization Criteria

Admit children who meet any of the following criteria:

• Oxygen saturation ≤92% in room air requiring supplemental oxygen 1
• Sustained tachycardia, inadequate blood pressure, or need for pharmacologic support 1
• Altered mental status from hypercarbia or hypoxemia 1
• Increased work of breathing (retractions, nasal flaring, use of accessory muscles) with inability to maintain oral hydration 1

Inpatient Management

• Obtain chest radiograph (posteroanterior and lateral) to document pneumonia and identify complications 2
• Provide supplemental oxygen to maintain SpO2 >92% 1
• Monitor vital signs every 4 hours or more frequently if clinically indicated 3
• Obtain tracheal aspirates for viral testing if mechanical ventilation is required 2

Monitoring for Bacterial Co-infection

Clinical deterioration or lack of improvement within 48-72 hours should prompt evaluation for secondary bacterial infection. 1

If bacterial co-infection is suspected based on clinical deterioration with increased systemic inflammation:

• For outpatients: Start amoxicillin 90 mg/kg/day in 2 divided doses 2
• For hospitalized patients: Start ampicillin, ceftriaxone (50-100 mg/kg/day), or cefotaxime (150 mg/kg/day) 2, 3
• Consider adding a macrolide (azithromycin 10 mg/kg day 1, then 5 mg/kg days 2-5) for school-aged children if atypical pathogens are suspected 2

Immunocompromised Children

Immunocompromised pediatric patients with hMPV infection have significantly higher rates of lower respiratory tract infection (29%) and mortality (5%), with severe disease more likely in neutropenic patients. 4

Risk Stratification

High-risk patients include those with:

• Hematologic malignancy (44% of severe cases) 4
• Hematopoietic stem cell transplant recipients (16% of severe cases) 4
• Solid organ transplant recipients 4
• Active neutropenia (significantly associated with severe disease, P=0.02) 4
• Age <6 months or >65 years 5

Management Approach

• Hospitalize all immunocompromised children with confirmed or suspected hMPV infection due to high risk of progression to severe disease 4
• Provide continuous cardiorespiratory monitoring 3
• Maintain oxygen saturation >92% with supplemental oxygen as needed 1
• Monitor for progression to lower respiratory tract infection, which occurs in approximately 29% of immunocompromised patients 4

Consideration of Ribavirin and IVIG

While 16% of immunocompromised children in published series received ribavirin, intravenous immunoglobulin, or both, the benefits of these treatments require further evaluation as efficacy remains unclear. 4, 5

• Ribavirin has shown in vitro activity and efficacy in animal models but lacks robust clinical trial data in children 6, 7, 8
• Consider ribavirin and/or IVIG only for severe, life-threatening disease in immunocompromised patients as a last resort, recognizing the lack of proven efficacy 5
• These agents should be reserved for patients with severe respiratory failure or those requiring intensive care unit admission 4

ICU Admission Criteria

Transfer to intensive care for:

• Oxygen saturation ≤92% despite FiO2 ≥0.50 1
• Impending respiratory failure (grunting, severe retractions, apnea) 3
• Need for mechanical ventilation or cardiovascular support 1
• Altered mental status due to hypercarbia or hypoxemia 1

Follow-up and Monitoring

• Clinical improvement should occur within 48-72 hours of appropriate supportive management 2, 1
• Obtain repeat chest radiographs only if the child fails to demonstrate clinical improvement or has progressive symptoms within 48-72 hours 2, 1
• Repeated chest radiographs are not routinely required in children who recover uneventfully 2, 1

Common Pitfalls

• Do not prescribe antibiotics empirically for viral hMPV infection without evidence of bacterial co-infection, as this contributes to antimicrobial resistance 2
• Do not delay hospitalization in immunocompromised children or those with severe respiratory distress, as mortality can occur 4, 6
• Do not use ribavirin routinely in immunocompetent children, as there is no evidence of benefit and it should be reserved only for severe disease in immunocompromised patients 4, 5
• Recognize that 23% of immunocompromised children with hMPV require ICU admission and/or supplemental oxygen ≥28% FiO2 4