Vox – The Covid-19 vaccine requires two doses. Studies show as many as 50 percent of people could miss the second one. “When we talk about the Covid-19 vaccines, we aren’t necessarily talking about people getting one shot, then being done and good to go. Both the Pfizer and Moderna vaccines — which are the closest to approval — have two-dose regimens. You get one shot, and then a few weeks later, you’re supposed to get another one. Among all the logistical challenges in distributing and administering a Covid-19 vaccine, this looks like one of the biggest. That’s because, based on research that evaluated compliance with other multi-dose vaccines, patients are really, really bad at getting their second dose. Bad as in, as many as half of patients never do. Studies conducted in both the US and UK on the hepatitis B vaccine — which, like the Covid-19 vaccines, is supposed to have around a one-month period between the first and second doses — found that roughly 50 percent of patients failed to get their follow-up shot within a year after their first…”