The association of medical experts with politically left-leaning cities and states early in the COVID-19 pandemic may have exacerbated vaccine hesitancy in right-leaning states of the US. Criticism from outside experts violates rules of communication between social groups (i.e. an intergroup sensitivity effect), leading to rejection of messages promoting vaccine safety and efficacy. In two studies, we document the effects of shared geographical group membership for medical expert messages promoting vaccination. We also found evidence that satisfying conversational norms against intergroup criticism reduces message rejection. Specifically, an invitation from ingroup political elites for a doctor to speak reduced the negative effects of unshared group identity.