Tamiflu-like Drugs Face Long Odds Against Covid ‘Runaway Tra
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The flu fighter Tamiflu is one of the most recognizable antiviral medications in the world -- but its weaknesses suggest that devising a similarly simple treatment for Covid-19 will be challenging.

“Putting that as your first line of defense is a dangerous choice to make," said Stephanie DeWitte-Orr, who studies antivirals and immunity at Wilfrid Laurier University in Waterloo, Ontario. While antivirals are an important backup in the fight against Covid, she said, in most cases, that’s all they should be –– a backup plan.

~ ‘Runaway train’

Tamiflu, otherwise known as oseltamivir, was developed by Roche Holding AG, approved in the US in 1999, and has been available as a generic since 2016. More than 100 regulators, approved the drug based on a rigorous review of its trials. Public health authorities including the World Health Organization and the Centers for Disease Control and Prevention, along with doctors’ groups, recommend it in their guidelines for flu treatment and prevention, Roche said.

Like most antivirals, Tamiflu blocks or slows replication of virus that’s already in the body. If taken quickly, Tamiflu can reduce the duration of infection by one to two days, studies show. “The benefits are, in an average healthy person, perhaps not that meaningful," said William Schaffner, a Vanderbilt University infectious disease expert who advises the US Centers for Disease Control and Prevention.

But, like Covid, flu infections mount relatively quickly. Most people don’t start taking Tamiflu within the recommended 48 hours from the start of infection, Schaffner said. The longer the virus stays on offense, the less effective the drug becomes. “It’s like trying to get in front of a runaway train," Laurier’s DeWitte-Orr said.

Another issue that can quickly arise with antivirals, especially when they’re overused, is resistance. The US spent more a billion dollars to stockpile Tamiflu before the 2009 pandemic caused by swine flu only for the virus to develop resistance, rendering the drug ineffective for millions.

~ Combating Covid

Numerous drugs have laid siege to Covid and failed, starting with the antimalarial drug hydroxychloroquine that was touted by former President Donald Trump. Other medications have met with some success. Like Tamiflu, Gilead Sciences Inc.’s remdesivir, the only Covid antiviral cleared for use in the U.S., aims to slow virus replication. But because it’s administered intravenously in the hospital over days, it’s inaccessible to people in the early stages of disease.

Monoclonal antibodies from Eli Lilly & Co. and Regeneron Pharmaceuticals Inc. target proteins on the viral surface, and appear effective at reducing related hospitalizations among high-risk patients. While these are used to treat patients before they become acutely ill, they must also be given by IV, and are costly.

A cheaper, oral alternative would be particularly attractive. “If we can get to something fairly cheap, like Tamiflu, that will be a major breakthrough," Woods said.