Studies find virus can cause body to fight itself

The coronavirus can warp the body’s defenses in many ways — disarming early warning systems, for example, or causing immune cells to misfire. But a spate of new studies suggests another insidious consequence: The infection can trigger the production of antibodies that mistakenly attack the patient’s own tissues instead of the virus.

The latest report, published online this week, suggests that autoantibodies can persist months after the infection has resolved, perhaps causing irreparable harm. If other studies confirm the finding, it may explain some of the lingering symptoms in people who have recovered from COVID-19. The syndrome, sometimes referred to as long COVID, can include dementia, “brain fog” and joint pain.

Autoantibodies are the misguided soldiers of the immune system, tied to debilitating diseases such as lupus and rheumatoid arthritis, which arise when the body attacks its own tissues.

The newest study is small, with just nine patients, five of whom had autoantibodies for at least seven months. It has not yet undergone peer review for publication, and the authors urged caution in interpreting the results.

“It’s a signal; it is not definitive,” said Dr. Nahid Bhadelia, medical director of the special viruses unit at Boston Medical Center, who led the study.

The question of autoimmunity following coronavirus infection is urgent and important, Bhadelia added. As many as 1 in 3 survivors of COVID-19 say they still experience symptoms.

“This is a real phenomenon,” she said. “We’re looking at a second pandemic of people with ongoing potential disability who may not be able to return to work, and that’s a huge impact on the health systems.”

A growing body of evidence suggests that autoimmunity contributes to the severity of COVID-19 in some people. A study published online in October found that among 52 patients with severe COVID-19, more than 70 percent carried antibodies against their own DNA and against proteins that help with blood clotting.

In another study, in the journal Science Translational Medicine in November found that half of patients hospitalized for COVID-19 had at least transient autoantibodies that cause clots and blockages in blood vessels.

“Once these autoantibodies are induced, there is no going back,” said Akiko Iwasaki, an immunologist at Yale University. “They will be a permanent part of the person’s immune system.”