'Why Some Covid-19 Patients Crash, The Body's Immune System Might Be To Blame'

'Why Some Covid-19 Patients Crash, the Body's Immune System Might Be To Blame,' NPR, April 7, 2020. (~ Lengthy article on a complex topic including 'cytokine storm' which has been brought up in earlier posts).

It's a strange and tragic pattern in some cases of COVID-19: The patient struggles through the first week of illness, and perhaps even begins to feel a little better. Then suddenly they crash. "We've seen some patients rapidly worsen," says Dr. Pavan Bhatraju, an assistant professor at the University of Washington who works in the intensive care unit at Harborview Medical Center in Seattle. "They initially were just requiring a little bit of oxygen. In 24 hours they're on a ventilator." A recent study by Bhatraju and others found that the patients' lungs appeared to deteriorate quickly. The crash typically happens seven days into the disease and can occur in young, otherwise healthy victims of COVID-19.

Now doctors and researchers are increasingly convinced that, in some cases at least, the cause is the body's own immune system overreacting to the virus. The problem, known broadly as a "cytokine storm," can happen when the immune system triggers a runaway response that causes more damage to its own cells than to the invader it's trying to fight. Cytokines are a wide cast of small molecules in the body that are released by certain cells to help coordinate the battle against infection. Although there's limited data on how the release of too many of these molecules (the cytokine storm) affects COVID-19 patients, some doctors are already treating people who have the disease with powerful anti-inflammatory drugs to try and slow or stop the process. Anecdotally, they say that the approach appears to be helping.

"The impact was dramatic," says Dr. Daniel Griffin, chief of infectious disease for ProHEALTH Care Associates, a group of physicians that serves the New York City area. The first six patients he treated all appear to be improving, at least for now, he says. "Yesterday was a good day."

But other researchers caution that the untested treatments carry significant risks. Suppressing the body's immune system at the exact moment it's trying to fight off the deadly coronavirus could have all sorts of unintended consequences, warns Dr. Tobias Hohl, the chief of infectious disease at Memorial Sloan Kettering Cancer Center in New York City. "The infection could get worse," Hohl says. Nevertheless, Hohl and others believe that controlling cytokine storms will turn out to be a critical way to help at least some of the sickest COVID-19 patients. And clinical trials already underway in New York and elsewhere could soon provide data about how existing drugs should be used. "I think in a month or two we're going to be able to help patients with COVID-19, who are dying from cytokine storms, and potentially bring the mortality rate down," says Dr. Randy Cron, an immunologist at the University of Alabama at Birmingham.

- Collateral damage

The body's immune system is, at the moment, the most effective weapon people have against COVID-19. The majority of patients can cure themselves of the disease simply by resting at home — enabling a small army of their own cells to attack the infection. Those cells make it harder for the virus to replicate, and help to develop antibodies that prevent it from infecting new cells. Those antibodies also likely help provide some protection against reinfection by the COVID-19 virus further down the road. But the army of the immune system can also do collateral damage, Jessica Hamerman, an immunologist at Benaroya Research Institute in Seattle, explains. When immune cells try to fight an infection, "they make a lot of toxic molecules, and those toxic molecules can cause a lot of tissue damage." The results are familiar to many people who've had the flu: Aches, fever and inflammation are actually symptoms of the immune system's attack, not of the influenza virus itself.

Cytokine storms occur when the immune system gets stuck trying to fight a disease...

More, https://www.npr.org/sections/health-shots/2020/04/07/828091467/why-some-covid-19-patients-crash-the-bodys-immune-system-might-be-to-blame