A flurry of headlines this week flooded social media, documenting a seemingly concerning case of COVID-19 in a San Diego nurse who fell ill about a week after receiving his first injection of Pfizer’s coronavirus vaccine. Experts said the sickness is nothing unexpected: The protective effects of vaccines are known to take at least a couple of weeks to kick in. Reporting that a half-vaccinated person contracted the virus is “really the equivalent of saying someone went outside in the middle of a rainstorm without an umbrella and got wet,” said Dr. Taison Bell, a UVA critical care physician.&nbs...