For the past week, Dr. Gregory Yu, an emergency physician in San Antonio, has received the same daily requests from his patients … They ask him for ivermectin, a drug typically used to treat parasitic worms that has repeatedly failed in clinical trials to help people infected with the coronavirus. … Prescriptions for ivermectin have seen a sharp rise in recent weeks, jumping to more than 88,000 per week in mid-August from a prepandemic baseline average of 3,600 per week, according to researchers from the CDC.