A preliminary study of the Covid vaccine from Pfizer suggests that it may be effective against a mutation found in the new variants of the virus. These variants, which appeared first in Britain and South Africa, appear to be even more contagious than the original. Though the study focused on only one of the vaccines available in the West, the versions produced by Moderna and AstraZeneca are in the process of similar testing. All three provide immunity by stimulating the production of antibodies against multiple spots on the spike protein coating the virus. Dr. Frederic Bushman of the University of Pennsylvania tracks how the coronavirus mutates. “A mutation will change one little place," he explains, "but it’s not going to disrupt binding to all of them.” Multiple agencies continue to monitor the virus for mutations. The U.S. Food and Drug Administration reports that this one does not affect the accuracy of most tests that look for the genetic code of the virus. Studies of rapid tests, which look for antigens, are still ongoing.