Abstract
Objective: Co-vaccination, or receiving multiple vaccines at once, may improve vaccination uptake and reduce missed opportunities to vaccinate. Although generally considered safe and effective, co-vaccination is not well accepted outside of travel and childhood immunization. Myriad psychological, physical and social influences affect vaccination decisions, but limited work has explored modifiable factors associated with co-vaccination comfort. Identifying such factors may better inform interventions targeting co-vaccination. Methods: This cross-sectional study examined how capability, opportunity, and motivation (COM-B model) relate to co-vaccination comfort among United States (U.S.; N = 604) and Canadian (N = 586) adults in January 2024. Index variables representing capability, opportunity, and motivation were constructed from survey items. Linear regression models were used to assess independent associations of capability, opportunity, and motivation with co-vaccination comfort. Results: All factors were positively associated with co-vaccination comfort in both samples. Capability was the strongest predictor (U.S.: β = 4.82, 95 % CI [4.24, 5.4]; Canada: β = 4.28, 95 % CI [3.7, 4.88]), followed by opportunity (U.S.: β = 4.1, 95 % CI [3.6, 4.6]; Canada: β = 4.1, 95 % CI [3.61, 4.59]), and motivation (U.S.: β = 2.94, 95 % CI [2.61, 3.27]; Canada: β = 2.57, [2.24, 2.9]). Conclusions: This study leveraged the COM-B model to identify behavioral factors associated with co-vaccination comfort. Future experiments should examine whether manipulating these factors impacts co-vaccination decisions.