The drama in Jonathan Spector’s Eureka Day, a play set at an ultra progressive elementary school in Berkeley, California, is ignited by a viral outbreak. First staged in 2018, the virus in question is mumps. But just as with the coronavirus epidemic, the illness tests liberal parents and their purported commitment to inclusivity. When the topic of mandatory vaccination follows the surge, the show turns into a comedy of manners. A new staging features Helen Hunt in a starring role. —Jensen Davis