TORONTO -- While some COVID-19 patients experience mild symptoms and recover on their own at home, others appear to be healthy one minute and in hospital fighting for their lives the next.
This rapid deterioration, along with other clinical signs, have led some researchers to believe that certain patients鈥 immune systems are betraying them by overreacting to the virus.
The phenomenon is broadly known as a 鈥渃ytokine storm鈥 and it has been well-documented since long before the world became aware of the new coronavirus. In fact, who believe cytokine storms may explain why otherwise healthy young people died from the Spanish flu in 1918.
According to Dr. Douglas Fraser, a lead researcher and pediatric critical care physician at London Health Sciences Centre in Ontario, a cytokine storm can occur when the immune system initiates an 鈥渆xaggerated鈥 response to an infection.
During an immune response, the body produces cytokines, which are molecules that are released by certain cells into the bloodstream to help co-ordinate an attack against the infection. Ordinarily, the body fights produces enough cytokines to fight off the virus or bacterium and then stops once the invader has been defeated.
In a cytokine storm, the immune system goes into overdrive and continues to release the molecules, which then end up attacking the very organs they were intended to protect.
鈥淭he idea would be that cytokines are produced and released at much, much higher amounts that cause harm to the body,鈥 Fraser, to COVID-19, explained during a telephone interview with CTVNews.ca on Tuesday.
If left untreated, the effects of this overreaction by the immune system can lead to fatal outcomes from complications such as multi-organ failure, lung inflammation, bacterial pneumonia, and respiratory distress.
In the current pandemic, Fraser said the research on how cytokine storms may affect COVID-19 patients is still very much in its infancy. However, recent and appear to provide evidence of elevated levels of cytokines and other immune molecules characteristic of a cytokine storm in COVID-19 patients.
Fraser said physicians have observed in their patients high fevers, elevated levels of the protein ferritin, which occurs during inflammation, and multiple cell lines with low levels of hemoglobin, white blood cells and/or platelets.
鈥淎ll of these things can occur from elevated cytokines,鈥 he explained. 鈥淪o there's no evidence, no convincing evidence yet to show that a cytokine storm is occurring; however, it鈥檚 been suggested, based on these clinical symptoms.鈥
TREATMENT FOR THE STORM
While there is some speculation that cytokine storms may explain why younger, otherwise healthy, individuals have died from COVID-19, Fraser said it鈥檚 still too early to know if that鈥檚 the case.
鈥淚t could be from a whole variety of factors, everything from genetics to pre-existing conditions, maybe people just don't know about yet, or, or haven't been discovered yet,鈥 he said. 鈥淲e just don鈥檛 know why certain people are getting sick and why certain people are not.鈥
Fraser said there could be a number of reasons why some individuals become deathly ill from the disease and others don鈥檛. In order to understand these different outcomes, he said researchers have to investigate the cytokines and other molecules present in COVID-19 patients.
鈥淭he goal is to determine what exactly is happening with the immune system and the inflammation it鈥檚 causing,鈥 he said.
To achieve this, Fraser and a team of researchers from Lawson Health Research Institute and Western University have been collecting daily blood samples from presumed COVID-19 patients over the past two weeks to test for inflammatory biomarkers and monitor how they change over time.
The information is then compared to that of other patients with infections unrelated to COVID-19.
鈥淲e鈥檙e comparing those samples to see what molecules have changed,鈥 he said. 鈥淭he important aspect there is that we identify which cytokines and molecules are different, then we can start to develop therapies that are specific against them.鈥
There are already some treatments that have been used to help reduce cytokine storms in the past, but it鈥檚 still not clear how effective they would be in COVID-19 patients.
the use of steroids, intravenous immunoglobulin or donated blood containing healthy antibodies, and drugs used to suppress cytokines, such as tocilizumab and anakinra.
The problem with these treatments, according to Fraser, is they鈥檙e not necessarily patient-specific, which is important when dealing with the individual complexities of immune responses.
鈥淚t all depends on what cytokines are released, because there鈥檚 a whole family of them, and it also depends on where they're released and from what cell,鈥 he explained.
That鈥檚 why Fraser said he鈥檚 hopeful the results of his study will provide some insight into how the immune system reacts to COVID-19 and which specific therapies should be used to treat certain patients.
