COVID-19 is a new viral pandemic and there is limited information regarding effective pharmacological therapy for prophylaxis and treatment.
The antiviral medication Oseltamivir (available under different trade names: Tamiflu & Cipla oseltamivir) is proven [as per recent research outcomes] not effective against COVID-19.
A retrospective case series (Wang D, et al. JAMA 2020) has published the outcomes of the use of oseltamivir in patients hospitalised with confirmed COVID-19 in China, and the authors noted no effective outcomes of oseltamivir were observed!
Oseltamivir (and other antiviral agents) are currently still under investigation in combination with other potential therapies, and more data will be available once those trials completed.
Currently the only indication for the use of Oseltamivir in COVID-19 patients is for proven co-infection with Influenza.
To gain insight and overview of planned or ongoing studies of drugs for the treatment of COVID-19, please check the following WHO Blueprint