There is no evidence that having a drink or two can render any of the current Covid vaccines less effective. Some studies have even found that over the longer term, small or moderate amounts of alcohol might actually benefit the immune system by reducing inflammation. Heavy alcohol consumption, on the other hand, particularly over the long term, can suppress the immune system and potentially interfere with your vaccine response, experts say. Since it can take weeks after a Covid shot for the body to generate protective levels of antibodies against the novel coronavirus, anything that interferes with the immune response would be cause for concern. “If you are truly a moderate drinker, then there’s no risk of having a drink around the time of your vaccine,” said Ilhem Messaoudi, director of the Center for Virus Research at the University of California, Irvine, who has conducted research on the effects of alcohol on the immune response. “But be very cognizant of what moderate drinking really means. It’s dangerous to drink large amounts of alcohol because the effects on all biological systems, including the immune system, are pretty severe and they occur pretty quickly after you get out of that moderate zone.”