Using Paxlovid and Tamiflu Together in COVID-19 and Influenza Co-infection
When a patient has confirmed or suspected co-infection with both COVID-19 and influenza, administer oseltamivir (Tamiflu) and nirmatrelvir/ritonavir (Paxlovid) concurrently according to standard treatment guidelines for each infection, without modification of either therapy. 1
When to Suspect and Test for Co-infection
Test for influenza co-infection using PCR or rapid testing of nasopharyngeal secretions when influenza is clinically suspected in any COVID-19 positive patient, as documented co-infection rates range from 0.5-2% in most studies, though some report up to 4.5% in certain populations. 1, 2
The most common symptoms in co-infected patients include fever (85.71%), cough (82.14%), and dyspnea (60.71%), which are indistinguishable from COVID-19 alone. 3
Co-infected patients may experience more severe clinical conditions compared to those with COVID-19 alone, making early identification and treatment critical. 3
Treatment Approach
Concurrent Antiviral Therapy
For confirmed influenza co-infection, start oseltamivir or baloxavir according to standard influenza treatment guidelines while continuing COVID-19 specific therapies concurrently without dose modification. 1
Paxlovid has demonstrated a 39% reduction in hospitalization risk (95% CI 36-41%) and 61% reduction in death risk (95% CI 55-67%) in COVID-19 patients, with particular benefit in those aged 65+ years. 4
The combination does not require special dosing adjustments, as oseltamivir does not have clinically significant interactions with nirmatrelvir/ritonavir. 5
Drug Interaction Management
Before initiating Paxlovid, review all concurrent medications for potential CYP3A interactions with ritonavir, as this is the most critical safety consideration. 5
Out of 190 commonly prescribed drugs, 57 require no special measures with brief, low-dose ritonavir treatment, while 15 require dose modification, 8 can be temporarily discontinued, and 9 contraindicate ritonavir use. 5
Empirical antiviral therapy should be rapidly de-escalated based on microbiology test results and clinical response to avoid unnecessary drug exposure. 6
Additional Management Considerations
Consider empirical antibiotics if bacterial superinfection cannot be ruled out, as bacterial co-infection occurs in approximately 40% of viral respiratory infections requiring hospitalization. 1
Maintain any bispecific antibody or immunosuppressive dosing during influenza treatment if the patient is already on such therapies. 1
Follow standard isolation protocols for both infections until clinical resolution. 1
Prevention Strategy
Influenza vaccination is strongly recommended for all COVID-19 patients and their close contacts to reduce the risk of co-infection and simplify clinical management. 1
This preventive approach is particularly important given that co-infection can lead to more severe disease without necessarily prolonging hospital stay. 3