In the quarantined Chinese city of Wuhan, health workers fighting the explosive outbreak of a new coronavirus have been improvising for weeks, trying to provide whatever care they can for Covid-19 patients whose symptoms range from a cough and fever to severe pneumonia, septic shock, and organ failure. In addition to treating these symptoms with oxygen therapy, ventilators, and antibiotics, doctors there have also resorted to experimentation. With no approved treatments for any of the illnesses caused by coronaviruses, health workers have been trying everything from steroids and antibodies to drugs normally intended for HIV and influenza. But because these treatments have been dispensed on a case-by-case basis, without any rigorous, centralized tracking of results, it’s hard to know if any of them are effective against the new disease.

Now, researchers in China are racing to launch more systematic tests of these repurposed medicines. Since January 28, scientists have registered 19 clinical trials in China, and at least a few have already begun dosing patients. With initial results expected as early as April, the swift leap into clinical research is an important one for frontline health workers desperate for hard evidence about which therapies work best. The trick will be making sure that evidence stacks up.

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“When you have a treatment, you can measure different things in a patient,” said Marie-Paule Kieny, WHO’s assistant director general of health systems and innovation, at a press conference Wednesday. “What is important if you want to compare different treatments is that everybody measures the same.” Her remarks came at the conclusion of a two-day summit convened by the WHO that brought together major funders and more than 300 scientists to define the most pressing research priorities of the current outbreak.

Chinese scientists who attended in person or virtually pushed for two urgent, short-term requests, according to Kieny, who cochaired the summit. The first is creating simpler tests for diagnosing Covid-19 that doctors could use at patients’ bedsides or even out in the field as part of community screening programs. Currently, the only tests available require time-consuming lab work, which means that biological samples have to be shipped to qualified hospitals where backlogs can quickly build up. The second is for the global medical community to produce standardized treatment plans with a strong data-collection component. In other words, they want to know what’s working for the sickest patients.

WHO’s director general, Tedros Adhanom Ghebreyesus, said Wednesday that the organization is now in the process of developing a master plan for coordinating clinical trials. The framework is intended to create consistency across studies of different treatments so the data can be compared directly as it comes in.

A randomized, controlled trial is the gold standard of clinical research. But pulling one together for Covid-19 is complicated by the realities of working in hospital systems overwhelmed by the sheer size of the outbreak. One of the biggest issues is ensuring the same standard of care in every place where the drug is being tested, says Nahid Bhadelia, medical director of the Special Pathogens Unit at Boston University’s National Emerging Infectious Disease Laboratories. “You can’t determine if a drug works unless the rest of the treatment received by patients is also the same,” says Bhadelia.

That gets much harder during a public health emergency like the one hitting Hubei province, where more than 48,000 people have fallen ill. Reports from the region show hospitals pushed to the brink—long lines, crammed wards, people being turned away—as the crush of patients has not yet been alleviated by the rushed construction of field hospitals and temporary quarantine structures.

But what researchers there do have going for them is a deep and growing expertise in clinical trials. About 20 percent of all clinical trials are now conducted in China, up from 10 percent five years ago, Thompson Reuters recently reported. That includes nearly 500 ongoing trials in the city of Wuhan, which has been hardest hit by Covid-19. The outbreak has disrupted some of these studies, as the doctors and facilities once dedicated to them have become a front line in the epidemic. But it has provided no shortage of willing patients on which to test potential Covid-19 treatments.

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Two trials, which The New York Times reported began recruiting patients last week, will test the efficacy of remdesivir, an experimental antiviral produced by American drugmaker Gilead. It works by blocking the enzyme that many viruses use to replicate inside human cells. It has not yet been approved for any use, but it does appear to be safe, according to the results of a 2018 clinical trial of Ebola patients in the Democratic Republic of the Congo. Though this will be its first test against coronaviruses in humans, scientists in China recently reported that remdesivir proved effective at preventing SARS-nCoV-2 (the virus that causes Covid-19) from infecting primate cells.