Rare, post-COVID complication seen post-COVID vaccination

But researchers unclear on whether vaccination caused MIS in 3 adults

BOSTON — Last winter, doctors at a Kaiser Permanente Hospital in Southern California documented three adults who came down with Multisystem Inflammatory Syndrome or MIS. MIS is a rare complication of COVID-19 infections, especially in children, where it is designated MIS-C. In adults, it is known as MIS-A.

The three, ages 20, 40 and 18, had in common two things: their diagnoses were preceded by at least one shot of the Pfizer/BioNTech COVID-19 vaccination and they had lab evidence and/or a clinical history of COVID-19 infections.

“There’s actually nothing in this paper at all that suggests an association between vaccination and MIS-C or MIS-A,” said Dr. Mark Schleiss, a professor of Pediatrics at the University of Minnesota Medical School. “Because we don’t have any report in this paper of the vaccine itself producing that syndrome.”

In addition, Schleiss said it’s important to consider, in this case, what’s known as ‘the biological plausibility of an association.’

“Knowing what we know about the virology of the virus and the immune response to the virus, why would we postulate that the vaccine would unmask or produce MIS-C or MIS-A to any greater extent than the natural infection itself,” Schleiss said.

The problem, of course, is that, just as researchers are still learning about the virus, they are still learning about the vaccines, which came to market without years of ascertaining every side effect possible.

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“The vaccine obviously works in your body by creating antibodies, which help fight the virus,” said Dr. Michael Koster, division director of Pediatric Infectious Diseases at Hasbro Children’s Hospital in Providence, R.I. “And the question is whether some of these post-infectious inflammatory syndromes like MIS-C or MIS-A are actually from the antibodies themselves or they’re from direct inflammation from the virus.”

Koster said, while that question hasn’t been settled, he has seen a pathology report out of Brazil that would seem to exonerate the vaccines.

“In most of the cases of MIS-C in children who unfortunately had passed away, they found virus particles everywhere in the body,” Koster said. “So, to me, that suggests more likely that this is from a cytotoxic effect from the virus itself causing inflammation.”

Still, Koster said, it’s important researchers continue to notice clinical issues that arise around the time of vaccination, even if it turns out there is no connection.

“Remember, we’re looking for potential side effects of the vaccine and, if anything, these kinds of reports are looking for any signals that exist out there,” Koster said. “And this is a testament to the robust reporting system that we have.”

Koster points out though that these three reports came out early in the nation’s vaccination campaign and that, since then, it’s not a ‘signal’ that’s been high on the radar. Knowing COVID-19 infections can cause MIS-C or MIS-A, and knowing vaccination can prevent those infections, he sees no reason for parents to worry about immunizing their adolescents.

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