As a third type of vaccine started shipping this week, and in light of ongoing strain across states trying to allocate vaccine doses, the CDC has updated its guidance for how to prioritize delivery of the vaccine.  Based on prior research about COVID among different populations, the CDC this week suggested that many underlying medical conditions (including dementia, heart conditions, cancer, and other common issues) may be used to set state standards about vaccine administration priorities.  The CDC has not departed from the existing guidance about vaccinating essential workers, over-65s, or other populations; but suggests that states consider the listed conditions among other factors when evaluating how to distribute vaccines.