We are living in a post-pandemic respiratory landscape where seasonality is less predictable than in years past. After COVID-19 began to recede in 2022, many facilities experienced the so-called “tripledemic” winter with influenza and RSV surging again. Since then, respiratory viruses have continued to circulate in less predictable patterns, with norovirus adding further complexity in many long-term care settings.

Against this backdrop, how has the current respiratory season been in your facility?

Emerging Signal in California

Influenza has remained the dominant respiratory virus in California headlines; however, human metapneumovirus (hMPV) has emerged more frequently as a contributing pathogen in recent seasons, including outbreaks in skilled nursing facilities in Southern California.

In some cases, respiratory viral panels performed in SNF settings have returned negative results, while hospitalized residents subsequently tested positive for hMPV—raising concerns about the timing of detection, testing techniques, and viral shedding dynamics.

Wastewater surveillance has also suggested early circulation in Northern California, with increasing levels reported in Southern California in subsequent weeks.

Why hMPV Matters in Skilled Nursing Facilities

hMPV is a negative-sense RNA virus in the Pneumoviridae family that causes acute respiratory tract infections ranging from mild upper respiratory illness to severe pneumonia and respiratory failure.

It is particularly relevant in long-term care populations due to the high prevalence of risk factors for severe disease, including:

• Advanced age
• Chronic lung disease
• Cardiovascular disease
• Immunosuppression
• Malnutrition

While often asymptomatic in up to 70% of healthy adults, approximately 50% of infected long-term care residents may develop pneumonia, comparable in severity to RSV and influenza in this population.

Key Clinical Questions About hMPV

• When does hMPV circulate?: Typically, from January through early June, peaking in March–April.
• What is the incubation period?: Approximately 4–6 days.
• How does it present?: Fever, cough, rhinorrhea, sore throat, headache, and myalgia. It may also worsen asthma or COPD.
• What are common lab or imaging findings?: May include leukocytosis or leukopenia, lymphopenia, and elevated inflammatory markers. Imaging may show peribronchial or proximal bronchial wall thickening extending from the hilum.

Testing and Diagnostic Considerations

How should hMPV be diagnosed in SNFs?
Use PCR-based respiratory viral panels with rapid turnaround when available (≤24 hours). Promptly test symptomatic residents and staff to support early cohorting and outbreak control.

Can the testing technique affect results?
Yes. The nasopharyngeal sampling technique is critical. The swab should be inserted parallel to the palate along the nasal floor until posterior nasopharyngeal resistance is met, rotated for several seconds, and then placed in transport media.

What if tests are negative but suspicion remains high?
Repeat testing within 24–48 hours of symptom onset and review specimen collection technique. Timing of viral shedding and collection quality may affect sensitivity.

Treatment and Clinical Management

• Treatment is primarily supportive care (oxygen, hydration, secretion management, monitoring)
• No approved antiviral or vaccine currently exists
• Corticosteroids are not routinely recommended unless treating underlying disease or severe complications
• Antibiotics should be reserved for suspected bacterial coinfection

When should bacterial coinfection be suspected?

• Purulent sputum
• Lobar consolidation
• High fever
• Leukocytosis
• Hypoxia or instability

Procalcitonin (if available):

• <0.25 ng/mL suggests a low likelihood of bacterial infection

CAP antibiotic options (if indicated):

• Beta-lactam + macrolide or doxycycline
• Respiratory fluoroquinolone monotherapy as an alternative
• MRSA coverage only if necrotizing pneumonia is suspected or severe deterioration is present

Infection Prevention and Control

How should facilities monitor for respiratory activity?

Coordinate with public health partners to track community viral activity. During high transmission periods:

• Encourage masking for visitors and HCP
• Consider masking residents when outside rooms
• Conduct daily symptom monitoring using a line list during outbreaks (per CDPH guidance)

How should staff and visitors be managed?

• Staff should perform self-screening before work
• Active screening may be required during outbreaks
• Symptomatic visitors should defer non-urgent visits
• Promote cough etiquette and respiratory hygiene signage throughout the facility

What is the role of ventilation?

Optimize airflow and indoor air quality in collaboration with facility engineering. HEPA filtration may be considered in shared or high-risk areas.

How should suspected cases be managed immediately?

• Test promptly
• Initiate transmission-based precautions immediately
• Early action is essential to limiting the spread

What outbreak control measures may be used?

• Single-room placement when possible
• HEPA filtration in shared rooms
• Avoid mixing symptomatic residents with new roommates
• Mask exposed roommates and avoid reassignment
• Pause group activities and communal dining during outbreaks
• Consult the local health department regarding admission restrictions
• Universal masking of residents in shared rooms may be considered but is not routinely practical

Reporting Criteria

Report when:

• ≥2 cases of acute respiratory illness (ARI) occur within 72 hours AND
• At least one laboratory-confirmed respiratory pathogen (excluding influenza or COVID-19) is identified

ARI definition:
At least two of the following: fever, cough, rhinorrhea/nasal congestion, sore throat, or myalgias.

Required Reporting Actions

When criteria are met:

• Notify infection prevention leadership, administration, and the medical director
• Report to the local health department (Title 17, CA regulations)
• Report to CDPH Licensing & Certification district office (AFL 23-08)
• Notify residents, families, and visitors per outbreak communication guidance

Human metapneumovirus (hMPV) is an increasingly recognized respiratory pathogen in California and typically peaks in late winter to spring. While it may be under-recognized due to overlap with other respiratory viruses and variable testing sensitivity, it carries a significant morbidity risk in skilled nursing populations.

For long-term care settings, the key priority remains early recognition of respiratory illness patterns and rapid implementation of infection control measures. Negative test results should not override clinical suspicion when outbreak conditions are present. If this topic has sparked your interest in infection prevention, CALTCM offers a valuable Infection Preventionist Orientation on-demand program. It covers many of the guidelines discussed in this article and provides additional resources and tools. Anyone working in a clinical role may benefit from completing this orientation and may notice a meaningful improvement in their ability to recognize and prevent outbreaks during upcoming respiratory illness seasons.