A small study offers a hint that an extra dose of COVID-19 vaccines just might give some organ transplant recipients a needed boost in protection. The vaccines offer strong protection to most people. But it’s not clear how well they work in transplant recipients and other people with weak immune systems. Researchers tested 30 transplant patients who, on their own, sought a third dose. It didn’t help everybody. But a third of those who appeared to have no protection after two shots developed virus-fighting antibodies with the extra dose. The research was published Monday in Annals of Internal Medicine.