When the Covid vaccines first came out, I thought everyone should get at least one shot. My belief was based on evidence that the vaccines significantly lowered the risk of bad outcomes (hospitalization/death), and on what was thought at the time to be the vaccines’ ability to prevent infection and transmission. For those in high-risk groups, like older people with underlying conditions, I thought the vaccine was important because it lowered their relatively high risk of dying from the virus. For young, healthier people I thought it was important to lower the risk of infection and transmission in order to protect more vulnerable populations. That was in late 2020 and early 2021. We now know a lot more about the vaccines and about acquired immunity. Most importantly, we know that while vaccines give good but waning protection from bad outcomes, they do not prevent a person from getting a Covid …