Overview
Clinical Frame
An adult vaccine visit is a risk and timing decision, not simply a search for a missing injection.
An adult vaccine visit is a risk-and-timing decision, not simply a search for a missing injection. The clinician matches the person's age, previous doses, immune function, pregnancy status, medical conditions, exposures, and provincial or territorial program to the vaccine that offers benefit now. The live-versus-non-live distinction drives several safety decisions. Inactivated, subunit, recombinant, toxoid, and mRNA vaccines present antigen without replicating infection, so they may generally be used in immunocompromised adults. Live attenuated vaccines replicate and are generally avoided in pregnancy and severe immunosuppression. If two live vaccines are not given on the same day, separate them by at least 28 days; non-live vaccines can be given at the same visit, using different anatomic sites. A missing record should prompt record retrieval and catch-up planning rather than an indefinite delay. Apply the current NACI guidance and the relevant provincial or territorial schedule, because eligibility, product availability, and public funding may differ across Canada. The same caution prevents importing US age thresholds or product rules into Canadian practice.