What is the treatment for a patient presenting with both influenza (flu) and Coronavirus disease 2019 (Covid-19)?

Treatment of Co-Infection with Influenza and COVID-19

When both influenza and COVID-19 are confirmed, treat both infections concurrently with oseltamivir or baloxavir for influenza according to standard guidelines while continuing COVID-19-specific therapies without modification. 1

Diagnostic Confirmation

• Test for both pathogens using PCR of nasopharyngeal secretions when clinical suspicion exists, as coinfection rates of 0.5-2% have been documented in COVID-19 patients 1, 2
• Obtain blood and sputum cultures if bacterial superinfection is suspected, particularly in patients with multidrug-resistant pathogen risk factors 2
• Consider procalcitonin testing to guide antibiotic decisions, as low values early in illness can safely guide withholding or early stopping of antibiotics in less severe disease 2

Antiviral Treatment Strategy

For Influenza Component:

• Administer oseltamivir or baloxavir immediately upon confirmation following standard influenza treatment guidelines 2, 1
• Do not delay or withhold influenza antivirals due to concurrent COVID-19 1

For COVID-19 Component:

• For hospitalized patients requiring oxygen: Dexamethasone 6 mg daily for up to 10 days 3
• For hospitalized patients or high-risk outpatients: Consider remdesivir - 200 mg loading dose on Day 1, then 100 mg daily maintenance doses 4, 3
• Treatment duration: 5 days for non-ventilated patients, 10 days for those requiring invasive mechanical ventilation/ECMO 4
• For mild-moderate COVID-19 in high-risk outpatients: Consider nirmatrelvir/ritonavir or monoclonal antibodies if available 3

Antibiotic Considerations

• Consider empirical antibiotics if bacterial superinfection cannot be ruled out, as bacterial coinfection occurs in approximately 40% of viral respiratory infections requiring hospitalization 1
• For low-risk inpatients: β-lactam (ampicillin-sulbactam, ceftriaxone, or cefotaxime) plus macrolide (azithromycin) or doxycycline, OR respiratory fluoroquinolone monotherapy 2
• For high-risk ICU patients: β-lactam plus macrolide OR β-lactam plus fluoroquinolone 2
• De-escalate antibiotics within 48 hours if cultures are negative and patient is improving 2
• Limit antibiotic duration to 5 days for most patients with community-acquired pneumonia 2

Supportive Care Measures

• Oxygen supplementation to maintain SpO2 >90-96% 3
• Thromboprophylaxis with anticoagulation given increased pulmonary embolism risk in COVID-19 3, 2
• Careful fluid management to avoid volume overload 3
• Monitor hepatic function and prothrombin time before and during remdesivir treatment 4

Critical Care Considerations

• For severe ARDS (PaO2/FiO2 ≤100 mm Hg): Implement prone positioning early 2
• Lung-protective ventilation with tidal volumes ≤6 mL/kg predicted body weight and plateau pressure ≤30 cm H2O 2
• Consider neuromuscular blockade and ECMO for refractory hypoxemia 2
• Avoid routine corticosteroids for viral pneumonia outside of COVID-19 indications 2

Important Caveats

• Do NOT stop immunosuppressive medications during influenza prophylaxis if patient is on bispecific antibodies or other immunotherapy 1, 2
• Patients with COVID-19 have longer illness duration (median 12 days) compared to influenza (median 7-9 days), so expect prolonged recovery 5
• COVID-19 patients require longer mechanical ventilation duration and have higher mortality risk (40% vs 19%) compared to influenza in ICU settings 6
• Monitor for drug interactions, particularly with lopinavir-ritonavir, nirmatrelvir-ritonavir, and other concurrent medications 2, 1
• Establish treatment escalation plans early, as COVID-19 patients may deteriorate rapidly 2