In the fight against Covid-19 though we might look forward in doom, one day we will look backward in awe. In an article last week, I discussed a promising drug combination to treat the disease. There is now new data supporting this treatment. Since then, Kansas City area physicians, including Joe Brewer, Dan Hinthorn and me, continue to treat many patients, and some have shown improvement. Major medical centers including the University of Washington and Mass General have added hydroxychloroquine to treatment options. So here’s an update, a response to some questions that have come up, and suggestions based on the latest information.

What is the treatment?

Physicians are using two drugs in combination—hydroxychloroquine and azithromycin, which I’ll abbreviate HC and AZ—to treat patients with advanced Covid-19 symptoms. We use a regimen reported in a recent open-label trial in Marseille, France, which was updated March 26, and which doctors may modify in any given case.

What is the evidence?

For HC, two bodies of evidence support its potential in treating Covid-19: in vitro (test tube) studies and initial clinical reports from the field. After the 2002-03 global outbreak of SARS, a coronavirus related to the one that causes Covid-19, an in vitro study conducted by doctors from the Centers for Disease Control and Prevention identified chloroquine (a relative of HC) as an attractive option for prevention and treatment. If added before the virus was introduced, the drug was highly effective in preventing cellular infection. Even later application markedly inhibited infection. Another contemporaneous study showed similar results. As for Covid, a Chinese study published March 9 showed HC has excellent in vitro effects. Other recent information suggests potential antiviral mechanisms of HC and chloroquine.