In fact, said Morris, in some cases, MIS-A patients “may have multiorgan dysfunction without [any] history of showing symptoms of COVID-19.”
Many patients show no ‘typical’ COVID-19 symptoms
That speaks to the bewildering nature of MIS-A, Femia said. MIS-A patients are testing positive for COVID-19 antibodies, but absent classic respiratory symptoms, many had no idea they were infected. But several weeks or even months later, they suddenly end up hospitalized with serious MIS-A symptoms. At that point, they are often no longer positive for active COVID-19.
“The timing of all of this is very difficult to establish,” Femia said. “We really don’t know how long after an infection with COVID this can happen, because antibodies can remain positive for a couple of months. I would say that, from a doctor’s perspective, our best guess is that this is likely to happen 4 to 6 weeks after infection, but it could be 3 to 4 months. We really don’t know.”
Dr. David Hirschwerk is an infectious disease specialist at Northwell Health in Manhasset, N.Y. “The timing of all of this suggests that MIS is driven not directly by the virus itself but by a post-infectious immunologic response that causes damage to the body,” he said.
“We think that it is relatively rare,” Hirschwerk added. “But we are all on the lookout for it now.”
Femia acknowledged that wasn’t always the case, given that in the early days of the pandemic “hospitals were overwhelmed, and it was a new disease, and this condition just wasn’t on the radar, which means we honestly don’t really know how many adults have gotten this.”
So, who is most at risk for MIS-A? Hirschwerk pointed to the CDC finding that “the vast majority of patients with MIS-A belonged to racial or ethnic minority groups.”
But, “like many things with COVID-19, it is all very new to us,” he added. “It requires more study, more data and more time.”
Femia agreed. But she noted that some characteristics of MIS-A are becoming both clear and worrisome. For example, “this has been seen in otherwise healthy patients, as well as among patients with underlying conditions, like obesity. So, the overall suspicion is that you probably don’t need as may co-morbidities to be at risk,” she explained.