Ten drugs have been cleared or recommended in the U.S. for use. Two of those later had their authorizations rescinded after they failed to work. The government recently paused shipments of a third because it wasn’t effective against new variants. The best medicines for early treatment are cumbersome to administer, and drugs for those in the hospital can only do so much for patients who are already severely ill.

“We’re really limited, to be honest,” says Daniel Griffin, chief of infectious disease at healthcare provider network ProHealth New York. “We do not have any dramatic treatments.”

A long list of factors played into the checkered development of drugs to treat Covid-19 cases—exposing flaws in the infrastructure of medical research and healthcare, particularly in fighting a fast-moving pandemic…

A few potential Covid-19 therapies in development have shown promise. Merck & Co. and Pfizer Inc. are each testing antiviral pills that could be taken at home soon after someone is infected. Merck’s widely anticipated pill, which it is developing with partner Ridgeback Biotherapeutics, hit a setback in April when it failed to help hospitalized patients. Researchers are still studying its effectiveness among the newly infected.