The MOSAIC study is an ongoing clinical trial run by the Canadian Center for Vaccinology, Canadian Immunization Research Network, COVID-19 Immunity Task Force, Vaccine Surveillance Reference Group (VSRG), and Dalhousie University studying the safety and efficacy of mixing and matching the Pfizer-BioNTech, Moderna and AstraZeneca COVID-19 vaccine products.^{1) 2)}