SARS-CoV-2 Can Cause A Mysterious Hyperinflammatory Syndrome In Adults Too

Adults infected with SARS-CoV-2 can develop a potentially fatal but little-understood "multisystem inflammatory syndrome," not dissimilar from the mysterious condition that's been seen in some children infected with the coronavirus. It's a small study, but researchers say it's something that doctors should keep their eye on during this uncertain time.

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This is according to a new paper in the Morbidity and Mortality Weekly Report published by the US Centers for Disease Control and Prevention (CDC) on Friday. Drawing on a number of previous case studies, researchers led by the CDC Covid-19 Response Team detail 27 patients who experienced severe symptoms relating to their heart, gastrointestinal system, skin, and brain — often without any sign of severe respiratory illness — and tested positive for a SARS-CoV-2 infection.

For example, many of the patients reported feeling ill with a fever, chest pain, heart palpitations, or stomach complaints. While many did not have a cough or any clear respiratory symptoms, they tested positive for a current or previous SARS-CoV-2 infection (either through nucleic acid, antigen, or antibody tests). Three of these 27 patients even died as a result of the disease.

"Although hyper inflammation and extrapulmonary organ dysfunction have been described in hospitalized adults with severe Covid-19, these conditions are generally accompanied by respiratory failure," the report reads.

"In contrast, the patients described here had minimal respiratory symptoms."

The syndrome appears to be incredibly rare – after all, this study included just 27 people. However, the researchers suggest that doctors and medical professionals be aware of the syndrome.

The report calls this condition multisystem inflammatory syndrome in adults (MIS-A). Perhaps most worryingly, it’s not necessarily clear if this condition is associated with a Covid-19 infection, as half of the patients did not appear to show any serious respiratory symptoms before the onset of the disease.

As the researchers note, this condition is remarkably similar to the multisystem inflammatory syndrome in children (MIS-C), a condition that was reported in the earlier stages of the pandemic. While children are widely accepted to have milder symptoms of Covid-19, these reports noted that a small handful of children were developing a “multi-system hyperinflammatory state, overlapping features of toxic shock syndrome and atypical Kawasaki disease.” Fortunately, this syndrome appears to be exceptionally rare, with just a few hundred documented cases in children worldwide.

The underlying causes of both MIS-A and MIS-C are not clear and much uncertainty currently surrounds the conditions. However, it’s noteworthy that all but one of the patients with MIS-A described in the report belonged to racial or ethnic minority groups; a similar trend to previous observations that people of Asian or Black ethnic origin appear to be at a higher risk of a severe Covid-19 infection.

"Long-standing health and social inequities have resulted in increased risk for infection and severe outcomes from Covid-19 in communities of color," the study notes.

The report also notes that just under one-third of the adult patients in the new report tested negative for SARS-CoV-2, although they tested positive for antibodies against the virus. According to the researchers, this suggests MIS-A and MIS-C “might represent postinfectious processes.” However, for now, there's is still much to learn about this unusual and apparently rare complication of SARS-CoV-2.

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