Data from the Recovery clinical trial testing dexamethasone as a treatment for people with COVID-19 showed that the steroid helped many of those who were sickest with the disease. The results showed that treatment with dexamethasone -- a cheap steroid that's been around for 60 years -- reduced the risk of death by about a third in patients on ventilators and by about a fifth in less-sick patients who only required oxygen.

But dexamethasone did not change the course of the disease for patients with milder symptoms who didn't require respiratory support, which makes sense considering why the steroid is helpful in the first place. The sometimes-fatal symptoms COVID-19 causes in extreme cases are apparently caused by an overreaction of the immune system to the coronavirus rather than the coronavirus itself. The steroid is thought to be acting to dampen the immune system, reducing that overreaction. In milder cases, there's no such immune system overreaction for it to ease.

Doctors in personal protective equipment

Image source: Getty Images.

Patients in another arm of the study had been being treated with hydroxycholoroquine, but that part of the study was halted earlier this month because, as other clinical trials have shown, there was no sign that the antimalarial drug was helping COVID-19 patients. The Food and Drug Administration revoked its emergency use authorization for hydroxycholoroquine and the related drug chloroquine this week based on evidence showing that the drugs are not effective against the novel coronavirus and can have dangerous side effects.

Dexamethasone, which has generally been prescribed to patients with certain inflammatory disorders and some types of cancer, is available as a generic from multiple drugmakers, so it'll be hard for any of the companies that make it (or their shareholders) to benefit significantly from the results.

On the other hand, the availability of a cheap treatment could hurt drugmakers, such as Gilead Sciences (Nasdaq: GILD), Eli Lilly (NYSE: LLY), Regeneron Pharmaceuticals (Nasdaq: REGN) and others, looking to develop effective treatments for COVID-19.

Of course, as those drugs may have different mechanisms of action than dexamethasone, some of them could eventually be authorized for use in combination with it, but studies to demonstrate whether such multi-drug treatment regimens are effective will take some time to set up and complete.

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