An international team of scientists has found distinct changes in the blood of people with long COVID, suggesting a potential strategy to diagnose and perhaps treat a mysterious condition that takes many forms. The important study, published on Thursday in the journal Science, adds to our understanding of long COVID, the lingering and often debilitating symptoms experienced by some people, by revealing shifts in proteins that the body produces in response to inflammation that may persist months after infection. It also detected blood clots and tissue injury. “We identified common patterns in l…