Oseltamivir for Post-Exposure Prophylaxis in Influenza
Yes, oseltamivir can be used for post-exposure prophylaxis in influenza and is recommended in specific high-risk situations, though it should not be used routinely outside of institutional outbreaks. 1, 2
Indications for Post-Exposure Prophylaxis
Post-exposure prophylaxis with oseltamivir should be considered for asymptomatic adults and children ≥3 months who are at very high risk of developing complications from influenza (e.g., severely immunocompromised persons) and for whom influenza vaccination is contraindicated, unavailable, or expected to have low effectiveness, after household exposure to influenza 1
Oseltamivir prophylaxis can be considered (in conjunction with influenza vaccination) for unvaccinated adults and children ≥3 months who are household contacts of a person at very high risk of complications from influenza (e.g., severely immunocompromised persons), after exposure to influenza 1
Oseltamivir is indicated for prophylaxis of influenza A and B in patients 1 year and older, according to FDA labeling 2
Timing and Duration of Prophylaxis
Post-exposure prophylaxis should be administered as soon as possible after exposure, ideally within 48 hours of exposure 1
Oseltamivir should not be administered for post-exposure prophylaxis if >48 hours has elapsed since exposure 1
The standard duration for post-exposure prophylaxis in a non-outbreak setting is 7 days after the most recent exposure to a close contact with influenza 1
For institutional outbreaks, prophylaxis may be continued for the duration of the outbreak 1
Dosing for Post-Exposure Prophylaxis
Adults and adolescents (≥13 years): 75 mg once daily for at least 10 days following close contact with an infected individual 2
Children (1-12 years): Weight-based dosing:
For children 3-11 months: 3 mg/kg once daily (though FDA labeling indicates prophylaxis is only for patients 1 year and older) 1, 2
Efficacy of Oseltamivir for Prophylaxis
Oseltamivir has demonstrated 82-89% protective efficacy in preventing laboratory-confirmed influenza illness in household contacts 3, 4
In post-exposure prophylaxis trials in household contacts, the incidence of laboratory-confirmed clinical influenza was reduced from 12% in placebo-treated subjects to 1% in oseltamivir-treated subjects 2, 5
A three-day regimen of oseltamivir has shown 93% protective efficacy in hospital ward settings when index cases were immediately isolated 5
Important Considerations and Limitations
Oseltamivir prophylaxis is not a substitute for annual influenza vaccination, which remains the primary means of influenza prevention 1, 2
Antiviral drugs should not be used for routine or widespread chemoprophylaxis outside of institutional outbreaks 1
Early empiric initiation of antiviral treatment can be considered as an alternative to post-exposure prophylaxis 1
Patients receiving prophylaxis should be informed that risk of influenza is lowered but not eliminated while taking medication, and susceptibility returns when medication is stopped 1
If a person receiving prophylaxis develops influenza-like symptoms, they should be tested for influenza and switched to treatment dosing, preferably with an antiviral drug with a different resistance profile if not contraindicated 1
Special Situations
For institutional outbreaks (e.g., nursing homes, hospitals), implement outbreak control measures including antiviral chemoprophylaxis when 2 cases of healthcare-associated laboratory-confirmed influenza are identified within 72 hours of each other in residents or patients of the same ward or unit 1
Neuraminidase inhibitors (oseltamivir or zanamivir) should be used for prophylaxis rather than adamantane antivirals due to widespread resistance to the latter 1
In immunocompromised patients, oseltamivir prophylaxis may be continued for up to 12 weeks 2
By following these evidence-based guidelines, oseltamivir can be effectively used for post-exposure prophylaxis to prevent influenza transmission in appropriate high-risk situations.