WASHINGTON (AP) — The National Institutes of Health is starting some studies to test possible treatments for long COVID. Millions of people are estimated to have the mysterious condition. The studies are small but each will tackle multiple possible therapies for things like brain fog, sleep disturbances and the theory that lingering virus may be at least partly to blame. The studies are part of the RECOVER project, which had to unravel what the most common and burdensome symptoms of long COVID are before doing studies.