High dose of Favipiravir helps prevent SARS-CoV-2 infection in hamsters whereas Hydroxychloroquine fails

Soumya Sarathi Ganguly, Indian Institute of Technology, Kharagpur

Virologists were working on two areas of SARS-CoV-2 research at KU Leuven Rega Institute. In one line developing a vaccine that can prevent infection, and in another line of research, they are thriving in search of existing drugs by which the amount of virus can be reduced in infected people, also called Drug repurposing. Hamsters were used by the researchers to test the efficacy of the antiviral drugs because the virus undergoes replication strongly after infection and develop similar lung pathology as that of mild COVID-19 in human, which is not the case with mice.

In this study, the team of researchers consisting of Suzanne Kaptein, Joana Rocha Pereira, Leen Delang, and Johan Neyts, gave either Hydroxychloroquine or Favipiravir to the hamsters in varying doses for 4-5 days. It is a broad-spectrum antiviral drug used against Influenza in Japan. SARS-CoV-2 infected the hamsters in two ways, one with direct infection by a high dose of virus in the nose, which is provided with the drug 1 hour before the infection. Furthermore, the other group of hamsters was injected with the drug one day before exposure by placing them in the same cage with an infected hamster. After four days of infection or exposure, the amounts of virus in the hamsters were observed. The results show a decreased viral amount in the hamsters treated with Favipiravir, before intranasal infection. The hamsters exposed to infected hamsters by sharing the same cage after Favipiravir treatment do not develop any infection. The hamsters which were not treated with Favipiravir developed an infection. On the other hand, Hydroxychloroquine does not have any impact on viral levels.

The high dose of Favipiravir makes the difference in decreasing the viral amount, but the low dosage does not impact the decrease in the viral amount in the infected hamsters. As the drugs were administered shortly before the virus’s exposure, it may also be used as a prophylactic to prevent the infection, as stated by Suzanne Kaptein. 

Delang states that humans can tolerate high doses of Favipiravir, as the drug’s high dosage does not show any side effects in a hamster or Ebola patients prescribed with a high dosage. As this drug is not developed against Coronaviruses, the drug’s potency is considered to be moderate.

The hamster model’s result suggests that a high dosage of Favipiravir has an antiviral effect, so clinical trials to test the drugs on humans were organized. So the researcher team concludes that the drugs against malaria, i.e., Hydroxychloroquine, do not have any efficacy against COVID-19 infection. However, the high doses of Favipiravir have an antiviral effect against SARS-CoV-2 in preventing infection and a decrease in the viral amount in infected individuals.

Also read: REVERBα (liver) gene – What about your midnight snack?

Reference:

1. Kaptein S, Jacobs S, Langendries L, Seldeslachts L, ter Horst S, Liesenborghs L et al. Favipiravir at high doses has potent antiviral activity in SARS-CoV-2−infected hamsters, whereas hydroxychloroquine lacks activity. Proceedings of the National Academy of Sciences. 2020;:202014441 doi: https://doi.org/10.1073/pnas.2014441117

2. https://www.sciencecodex.com/hydroxychloroquine-does-not-counter-sars-cov-2-hamsters-high-dose-favipiravir-does-658413 

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