Washington Post: “In the beginning, when the coronavirus was new, the quest for a vaccine was simple. Everyone started out susceptible to the virus. Shots brought spectacular protection. But the next chapters of life with the virus — and the choice of booster shots for the fall and beyond — will be complicated by the layers of immunity that now ripple through the population, laid down by past infections and vaccinations. When it comes to viral infections, past is prologue: The version of a virus to which we’re first exposed can dictate how we respond to later variants and, maybe, how well vaccines work. It’s a phenomenon known by the forbidding name of original antigenic sin, and, in the case of the coronavirus, it prompts a constellation of questions. Are our immune systems stuck still revving up defenses against a version of the virus that has vanished? Will updated booster shots that are designed to thwart variants be much better than the original vaccine? How often will we be reinfected? Is there a better way to broaden immunity?..”