Pfizer released new data Wednesday indicating vaccine efficacy starts to decline around five to six months after the second dose, not eight months as originally thought. It’s raising questions if the three to four week gap between doses for Pfizer and Moderna was long enough to make the second shot the most effective. “If this was a slow moving epidemic, you probably wouldn’t have seen these three week gaps,” said UCSF epidemiologist, Dr. George Rutherford. “You probably would’ve seen something longer.” “Why is that?” ABC7’s Stephanie Sierra asked. “Because it works better,” he said. “If you have a little more space in between, you get over your primary immune reaction and then you’re at the point where all your cells are primed and you can get a secondary immune reaction.” Rutherford says if we had a two month waiting period in between the first two doses of Pfizer and Moderna we may be in a little better place, but we will never know for certain. “Who knows? But we would’ve tolerated a lot more cases getting that second dose,” he said.