The controversy began in September, more than a year into the pandemic, when the Tennessee Board of Medical Examiners issued a warning to doctors in the state: Spreading misinformation about COVID-19 vaccines could land them in big trouble with the board, including the possible revocation of their medical licenses. Board members acted after hearing that some doctors were relaying fantastical, unsupported claims about the vaccines, including that they magnetize the body, cause infertility and inject microchips under the skin so the government can track patients’ movements. “First, do no harm,” …