Influenza Diagnosis and Treatment Guidelines (2025 Edition) Part 3

Sick Woman Covered With a Blanket Lying in Bed With High Fever and a Flu

IX. Differential Diagnosis

(A) Common Cold

The common cold primarily presents with upper respiratory catarrhal symptoms (e.g., rhinorrhea, nasal congestion), with mild systemic symptoms such as fever and myalgia.

(B) SARS-CoV-2 Infection

SARS-CoV-2 infection shares similar clinical manifestations with influenza and requires differentiation via etiological testing.

(C) Other Lower Respiratory Tract Infections

When pneumonia is present, differentiation from pneumonia caused by other pathogens (e.g., other respiratory viruses, Mycoplasma pneumoniae) is necessary through etiological testing.

 

X. Treatment

(A) General Principles

  1. 1. Isolation: Manage patients under respiratory isolation protocols.
  2. 2. Hospitalization Criteria (meet any of the following):
    • - Worsening underlying conditions (e.g., COPD, diabetes, chronic heart/kidney failure, cirrhosis).
    • - Meeting criteria for severe or critical influenza.
  3. 3. Home Care for Non-Hospitalized Patients:
    • - Isolate at home with room ventilation and mask use.
    • - Ensure adequate rest, hydration, and nutrient-rich diets.
    • - Monitor disease progression closely, especially in children and the elderly.
  4. 4. Early Antiviral Therapy for High-Risk Groups: Initiate antivirals promptly in patients at high risk for severe/critical illness to reduce symptoms, complications, duration, and mortality.
  5. 5. Antibiotic Stewardship: Avoid inappropriate antibiotic use. Monitor disease progression, collect specimens for etiological testing, and use antibiotics judiciously.
  6. 6. Antipyretic Use: Select antipyretics appropriately. Aspirin or aspirin-containing salicylate products are contraindicated in children.

(B) Symptomatic Management

  • - Fever: Physical cooling and antipyretics.
  • - Cough/Sputum: Administer antitussives and expectorants.
  • - Oxygen Therapy: Provide oxygen based on hypoxia severity.

(C) Antiviral Therapy

Antiviral treatment should prioritize initiating therapy within 48 hours of symptom onset for high-risk patients during influenza season, preceded by pathogen testing to confirm infection. For individuals presenting beyond 48 hours, antiviral therapy remains critical for high-risk groups or severe/critical cases with confirmed influenza, as well as for those at risk of transmitting the virus to vulnerable populations. Treatment duration may be extended for severe or critical cases based on pathogen analysis, while combination therapy using agents with identical mechanisms or dose escalation must be avoided.

Approved antiviral agents in China include neuraminidase inhibitors (NAIs), RNA polymerase inhibitors, and hemagglutinin inhibitors. Oseltamivir, available in capsule or granule form, is administered at 75 mg twice daily for adults, while pediatric dosing is adjusted by age and weight: children under 1 year receive 3.0–3.5 mg/kg twice daily (stratified by months of age), and those ≥1 year receive 30–75 mg twice daily based on weight categories (≤15 kg to >40 kg), with a standard 5-day course and renal dose adjustments.

Intravenous peramivir is dosed at 300 mg (600 mg for severe cases) infused over ≥30 minutes, repeatable daily for up to 5 days in adults, while pediatric dosing follows 10 mg/kg daily (maximum 600 mg) with renal function considerations. Inhaled zanamivir, contraindicated in asthma or chronic respiratory diseases, is prescribed as 10 mg every 12 hours for 5 days in patients ≥7 years. RNA polymerase inhibitors include baloxavir marboxil, given as a single weight-based oral dose (80 mg for ≥80 kg, 40 mg for 20–80 kg, and 2 mg/kg for <20 kg) for individuals ≥5 years, and favipiravir, which is restricted to adults with refractory influenza at 1600 mg twice daily on Day 1 followed by 600 mg twice daily on Days 2–5, strictly contraindicated in pregnancy. The hemagglutinin inhibitor arbidol is prescribed at 200 mg three times daily for 5 days.

These regimens emphasize precision in dosing, contraindication adherence, and patient-specific adjustments to optimize outcomes.

(D) Supportive Care for Severe/Critical Cases

Management focuses on addressing complications, treating underlying conditions, preventing or treating secondary infections, and providing organ-specific supportive care.

Conventional oxygen therapy is indicated for patients with a PaO2/FiO2 ratio ≤300. For those with a PaO2/FiO2 ratio ≤200, high-flow nasal cannula (HFNC) or non-invasive ventilation (NIV) should be initiated, accompanied by prone positioning when feasible. Mechanical ventilation is required for patients with a PaO2/FiO2 ratio ≤150 or significant inspiratory effort, particularly in children, and must adhere to lung-protective strategies. Refractory respiratory failure may necessitate extracorporeal membrane oxygenation (ECMO). Airway clearance techniques, such as vibration, chest oscillation, postural drainage, or bronchoscopy, are recommended to maintain pulmonary hygiene. Continuous monitoring of oxygenation and ventilation parameters is critical.

Patients with sepsis or shock require hemodynamic stabilization through fluid resuscitation and vasopressor therapy. Close monitoring of blood pressure, heart rate, urine output, and arterial lactate levels is essential. Cardiac biomarkers and electrocardiograms (ECG) should be assessed regularly to detect myocardial injury, which may arise from direct viral effects or exacerbation of pre-existing cardiovascular disease.

AKI management involves correcting hypoperfusion and discontinuing nephrotoxic agents. Continuous renal replacement therapy (CRRT) is indicated for hyperkalemia, severe metabolic acidosis, or fluid overload unresponsive to diuretics.

For encephalitis or encephalopathy, interventions target cerebral edema reduction and seizure control. Acute necrotizing encephalopathy (ANE) should be managed according to the 2023 pediatric ANE guidelines. Acute disseminated encephalomyelitis (ADEM) and transverse myelitis warrant corticosteroids and/or intravenous immunoglobulin (IVIG), while Guillain-Barré syndrome is treated with IVIG or plasma exchange.

Systemic corticosteroids are not routinely recommended but may be considered for refractory septic shock after risk-benefit analysis. Nutritional support and early rehabilitation are integral to recovery, tailored to the patient’s metabolic needs and functional status.

 

XI. Hospital Infection Control

  1. 1. Triage System: Implement pre-examination triage, enforce mask use for symptomatic patients/visitors, and promote hand/respiratory hygiene.
  2. 2. Isolation: Separate suspected/confirmed cases. Restrict visits and ensure mask use during transfers.
  3. 3. Ventilation and Disinfection: Maintain airflow and clean high-touch surfaces (wards, clinics, offices).
  4. 4. Waste Management: Dispose of medical waste properly; perform terminal disinfection post-discharge.
  5. 5. Staff Protection: Follow standard precautions (surgical masks, hand hygiene). Screen symptomatic staff and exclude infected personnel from work.

 

XII. Prevention

(A) Vaccination

  • ✅Most effective measure to reduce infection and complications. Recommended for all ≥6 months without contraindications.
  • ✅Priority Groups: Healthcare workers, elderly ≥60 years, chronic disease patients, pregnant women, children 6–59 months, caregivers of infants <6 months, and congregate settings (schools, prisons).

(B) Chemoprophylaxis

  • ✅Post-Exposure Prophylaxis: For high-risk close contacts (unvaccinated or unimmunized) within 48 hours of exposure.

(C) General Measures

  • ✅Hygiene Practices: Frequent handwashing, ventilation, avoiding crowded areas, and masking in public if symptomatic.
  • ✅Respiratory Etiquette: Cover coughs/sneezes with elbow/tissue; avoid touching face.
  • ✅Self-Isolation: Rest and isolate if symptomatic; wear masks during medical visits.

 

About Us: For efficient virus isolation, high-quality oropharyngeal swabs are essential. Mantacc produces medical-grade, sterile, and DNase/RNase-free flocked swabs compatible with viral transport media and molecular diagnostics, certified to ISO, CE, and FDA standards. Learn more at Mantacc 93050L Oral Sampling Swabs.

 

Related Post  

Influenza Diagnosis and Treatment Guidelines (2025 Edition) Part 1

Influenza Diagnosis and Treatment Guidelines (2025 Edition) Part 2

Oral Sampling Swabs: A Promising Alternative for Infectious Disease Diagnosis