The Coronavirus Patients Betrayed by Their Own Immune Systems

A patient battling a cytokine storm may have an abnormally fast heart rate, fever and a drop in blood pressure. Apart from a surge in interleukin-6, the body may also show high swirling levels of molecules called interleukin-1, interferon-gamma, C-reactive protein and tumor necrosis factor-alpha.

This storm, if it develops, becomes obvious a few days into the infection. But the sooner doctors catch on to it and treat it, the more likely the patient is to survive. Too late, and the storm may be beyond control, or may already have caused too much damage.

There is a relatively simple, rapid and easily available test that can detect whether a patient’s body has been taken over by a cytokine storm. It looks for high levels of a protein called ferritin.

But if the test does suggest a cytokine storm is underway, what then?

The seemingly obvious solution is to quell the storm, Dr. Cron said: “If it’s the body’s response to the infection that’s killing you, you need to treat that.”

The reality is trickier, especially given the lack of reliable data for Covid-19. But noting that drugs like tocilizumab are taken regularly by people with arthritis, Dr. Cron said the benefit would probably outweigh potential harm if someone is facing death.

“We need evidence-based data, but in a pandemic, where we’re flying by the seat of our pants, we always have to treat the patient in front of us,” he said.

Other drugs might also be useful against cytokine storms. For example, a drug called anakinra mutes interleukin-1, another of the wayward proteins. Clinical trials of anakinra for Covid-19 are also underway. A report published this week suggested that hydroxychloroquine, a much-spotlighted malaria drug that also calms an overactive immune response, might also be effective as a treatment for those who are mildly ill from coronavirus.