MIP-C Is a New COVID-Related Syndrome That Can Cause Severe Lung Scarring

Researchers have identified a previously overlooked syndrome related to COVID that causes severe lung scarring. The syndrome is called MIP-C, and experts want the public to be aware of its symptoms because they can arise in people who have had mild or asymptomatic cases of COVID.

An international team of researchers from the University of Leeds in the United Kingdom and the University of California San Diego School of Medicine identified the syndrome after a pandemic mystery arose in the U.K.

“This is not fearmongering. This is just something to be aware of,” Pradipta Ghosh, MD, a professor in the Departments of Medicine and Cellular and Molecular Medicine at UC San Diego School of Medicine and founder of the UC San Diego Institute for Network Medicine, told Verywell.

What Is MIP-C?

MIP-C, pronounced “mipsy,” is an acronym for MDA5-autoimmunity and interstitial pneumonitis contemporaneous with COVID. MIP-C is an inflammatory autoimmune disease with a link to COVID.

Anti-MDA5-positive dermatomyositis (MDA5⁺-DM) is a rare but serious autoimmune disease that was first described in 2005. The symptoms often include muscle pain, arthritis, rashes, and rapidly progressing interstitial lung disease (RP-ILD), which is severe lung scarring. MDA5⁺-DM can be fatal.

Researchers at the University of Leeds noticed a surge in MDA5⁺-DM cases in Yorkshire in the U.K. during the pandemic. The surge came as a surprise on its own, but also since the cases were showing up in a predominantly Caucasian population. Typically, MDA5⁺-DM presents in people of East Asian descent.

Dennis McGonagle, PhD, professor of investigative rheumatology at the University of Leeds, contacted Ghosh about the cases, because of some of her team’s previous work, and their collaboration began.

The patients were presenting to either their primary care physicians or to rheumatology clinics for joint pain, rashes, and muscle aches. “What they noted, is that some of these rapidly progressed to death because they were getting lung fibrosis,” Ghosh recalls of her initial conversation with McGonagle.

Many of the people presenting with MDA5⁺-DM didn’t know if they’d had COVID or had been exposed to it, Ghosh told Verywell. The Yorkshire population has high vaccination rates at 90%. However, the surge of infections with the Omicron and related variants at the time was so high that exposure to the virus was extremely high, “practically unavoidable,” Ghosh said.

Ultimately, McGonagle and Ghosh’s study uncovered that these cases of MDA5⁺-DM were an undiscovered COVID syndrome, which they labeled MIP-C. The acronym mirrors the labeling of MIS-C, which stands for multisystem inflammatory syndrome, a separate COVID-related condition seen in children.

Most people who contract COVID-19, especially those who are vaccinated, recover without experiencing severe complications like MIP-C or MIS-C. But the identification of these syndromes underscores the need for awareness and medical vigilance for those experiencing the unique symptoms of either one.

The researchers note in their study that similar cases have cropped up globally, so the syndrome is not limited to the U.K. Since their study was published, Ghosh said she’s received several emails from patients, or their family members, who also have been impacted by some form of lung disease and tested positive for anti-MDA5 antibodies. They were looking to see whether their symptoms or their loved one’s symptoms could be MIP-C.

“One email chronicled how delays in diagnosis and treatment were followed by the most dreaded outcome: death,” she said.

The Prevalence of MIP-C Is Still Small

The researchers conducted a retrospective observational study to review the surge in cases of MDA5⁺-DM in the Yorkshire population to figure out why it happened. Ultimately, they found 60 new cases from 2020 to 2022. Those cases translated to an increase from 0.4% in 2019 to 2.1% in 2020, 4.8% in 2021, and 1.7% in 2022.

Just eight out of the 60 cases had a history of confirmed COVID. However, the peak surge in the MDA5⁺-DM cases overlapped with Yorkshire’s COVID positivity rates in 2021, suggesting COVID was the likely culprit. The researchers noted that more than half (58%) of the 60 patients with MDA5⁺-DM had received COVID vaccinations.

With the help of computer technology, the researchers compared gene expression patterns in COVID to those of autoimmune lung disease and idiopathic pulmonary fibrosis. They found that patients who showed the highest level of MDA5⁺-DM response also had high levels of interleukin-15 (IL-15). IL-15 is a cytokine, or an immune system protein. The knowledge that IL-15 plays a role in MIP-C may help with further research and treatment development.

The researchers also found that some people have protection from MIP-C.

“If you have a specific [mutation] in the IFIH1 gene, there are lots of immune disorders that take a slightly different turn in those patients,” Ghosh says. “In the case of MIP-C, we found people with this mutation were protected from the raging immune response that we believe to be a driver or contributor for lung fibrosis.”

Why Understanding of MIP-C Is Important

Identifying COVID-related syndromes and sharing information about their common symptoms helps make people aware of what to look for.

MIP-C patients in Yorkshire tended to seek medical care at rheumatology clinics for rashes, muscle aches, joint pain, and more. But some also had trouble breathing, which is the most concerning symptom because the lung scarring can be fatal, Ghosh said.

“It is important for syndromes or patterns like MIP-C to be identified because it is crucial for medical recognition and treatment options,” Bernadette Boden-Albala, DrPH, MPH, the director of the UCI Program in Public Health and Founding Dean of the planned UCI School of Population and Public Health, tells Verywell. “Future research targeting MIP-C can better understand mechanisms involved and ultimately develop appropriate treatment and management strategies to reduce the impact of scarring on lung tissue.” Boden-Albala was not involved in the research.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.