I'm pleased to report that some 60 hours ago I received the second dose of the Moderna coronavirus vaccine, and I experienced no adverse consequences of any kind. My wife, who is in otherwise very good health, had a strong case of the chills, a low fever, and generalized weakness starting some 12 hours after receiving her 2nd dose, and for about 24 hours after that. These are relatively common side effects, see https://www.cdc.gov/coronavirus/2019-ncov/vaccines/different-vaccines/Moderna.html
As per my physician's recommendation, and to reduce the risk of a rare, immediate allergic reaction, I took a small dose of an antihistamine (a 25mg pill of Benadryl, or diphenhydramine), a half hour before my vaccination appointment.
I hope that you all manage to stay healthy until you get vaccinated. The newer strains of Covid-19 are far more contagious than the original, so I urge everyone to avoid drinking or eating with others indoors, and not to take off your masks when meeting with anyone else indoors or outdoors. In fact, here in the USA, the experts at the Centers for Disease Control (CDC) are now recommending that we also start using two (different) masks on top of each other, see https://www.cbsnews.com/news/double-face-mask-covid-19-cdc/