Scientists in Britain announced a breakthrough in the battle against coronavirus last week, reporting that they had found the first drug to reduce deaths among critically ill Covid-19 patients.
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The steroid dexamethasone is cheap and easy to obtain, but experts cautioned that people with mild illness, or no illness, should not take it.
The results were released for the first time in a poorly detailed press release. Now the full study, neither peer-reviewed nor published yet, has been published online, and it’s a surprise.
The drug, a cheap and widely available steroid called dexamethasone, appears to help patients in dire straits, the data suggests. But it can also be risky for patients with milder illnesses, and the timing of treatment is critical.
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The drug “may harm some patients, and we are not entirely sure who those patients are,” said Dr. Samuel Brown, an assistant professor of pulmonary and critical care medicine at the University of Utah School of Medicine in Salt Lake. City, who was not involved in the investigation.
Following the announcement last week, officials at some U.S. hospitals said they would begin treating coronavirus patients with dexamethasone, and the World Health Organization asked to speed up production to ensure an adequate supply. UK health officials moved to limit exports of the steroid.
The drug was tested in a clinical trial that included about 6,425 patients in Britain. A third were randomly assigned to receive the medication, while the others received usual care. Patients in the first group received a very low dose of the drug, administered daily for up to 10 days.
Dexamethasone was beneficial for those who had been ill for more than a week, reducing deaths by one third among patients with mechanical ventilators and by one fifth among patients who received supplemental oxygen by other means.
However, patients who received the steroid who were not receiving respiratory support actually died at a slightly higher rate than similar patients who did not receive the drug, although the difference was not statistically significant.
According to Dr. Martin J. Landray, lead author of the study and professor of medicine and epidemiology at Oxford University, it makes sense that the drug may have disparate effects at different stages of the disease.
In more seriously ill patients, the immune system goes into a damaging overdrive mode, triggering a so-called cytokine storm that damages the body, including the lungs.
“It is almost like a two-phase disease,” Dr. Landray said in an interview. “A phase where the virus dominates, and the immunological phase, where the damage caused by the immune system is dominant.”
Doctors have been concerned about using steroids like dexamethasone to fight Covid-19, because steroids are anti-inflammatory drugs that dampen the body’s protective immune response. In mildly ill patients, that can do more harm than good, Dr. Landray said.
“In the early phase of the disease, the immune system is your friend,” said Dr. Landray. “He is fighting the virus, and cushioning it is not a good idea.”
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“In the later phase, the immune system is no longer your friend: it is responsible for the failure of the lungs, and wetting it with steroids helps the situation and improves the chances of survival.”
Other experts agreed, saying that the study showed that dexamethasone cannot be used to treat minor illnesses or as a preventive.
“It would probably be harmful to take dexamethasone as an outpatient treatment for Covid-19,” said Dr. Brown. Patients with mild infections “should not try to get people to prescribe dexamethasone just in case.”
Many scientists want to see the results of the trial repeated in another study, noting that some questions are not fully answered in the document, including information about long-term results and neurological damage.
“If a reasonable fraction of patients are recovering in a satisfactory and welcome way, what you have is a gigantic victory,” said Dr. Jeremy Faust, an emergency room physician at Brigham and Women’s Hospital in Boston.
Overall, however, patients who have spent a lot of time on ventilators “have a difficult road ahead,” he added, even if dexamethasone improves their chances of survival.
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