Gupta and his team took antibodies from people vaccinated with the Pfizer shot and then looked to see how much the two mutations, when combined together, decreased the ability of these antibodies to kill the virus. What they saw was hopeful. The double mutant behaved a lot like the single mutant. It wasn't double trouble. "There didn't seem to be the addition of one mutant on top of the other," Gupta said. "And that was really quite important because that assumption has caused panic." The team published its findings online Sunday. At the same time, researchers at Emory University performed similar studies with antibodies taken from 15 people who have been vaccinated with either the Pfizer or Moderna shots. In these studies, the antibodies could still neutralize the B.1.617 variant, but the potency of the antibodies dropped by about sevenfold on average, the authors reported. "Despite this reduction, all vaccine blood samples ... still maintained the ability to block the B.1.617 variant," said immunologist Mehul Suthar at Emory, who led the study.