The best news of the past few months is that the three approved Covid-19 vaccines—the two-shot, mRNA-based ones from Pfizer and Moderna and the single-shot, adenovirus-vectored one from Johnson & Johnson—have one thing in common. They’re awesome. In trials, each prevented death and severe disease. But even though those are the endpoints that the vaccine makers tested, they aren’t the only important things to consider.
“We actually don’t know whether in real life, at the population level, that efficacy translates into vaccine effectiveness,” says Ana Bento, a disease ecologist at the Indiana University School of Public Health. “While it might protect you against disease, it might not protect you against infection. It’s too soon to actually know that.”
You can’t turn a marathon into a 100m dash in the middle of the race.➵