“If you go much lower than 50% then the lower bounds of things start to get to a place where vaccines may have very little efficacy,” Marks added. “On the other hand, if we held that number at 70% to 80% … we may not have a vaccine until there’s herd immunity that’s occurred naturally.”
However, Marks said that eradicating the virus will likely require a more effective vaccine. “We’re going to need a vaccine that’s probably in the order of 70% effective and 70%, at least, of the population is going to need to take it,” he said.