evidence: The problem with only two shots of the vaccine is that most of the antibodies your body generates don't have the potency to neutralize omicron when it first attacks your upper respiratory tract. That means you could easily get a breakthrough infection. (The good news is that for most people, the immune system does kick in to fight off severe disease once memory cells activate.) Laboratory studies have shown that antibodies, after only two shots, are 40 to 50 times less potent against omicron than against previous variants. [...] You see, right after your first two shots of the vaccine, your immune system rushes and makes a burst of antibodies. But these antibodies aren't so great. They especially aren't good at fighting off new coronavirus variants, says immunologist Ali Ellebedy at the Washington University School of Medicine. "That initial group isn't very well trained."