Rollout Strategy for the Pfizer-BioNTech COVID-19 Vaccine in Ontario

Administering Pfizer-BioNTech’s COVID-19 vaccine during the early stage of the vaccine rollout (January/February 2021) to as many individuals as possible would prevent more COVID-19 cases in Ontario as compared to reserving half of the initial allotments as second booster doses (Figure 1). On-label use of the vaccine with the administration of two doses is important, as the second dose significantly boosts the immune response and results in a substantial increase in neutralizing antibodies. However, using 100% of the initial allotments immediately to vaccinate as many individuals as possible does not preclude on-label use with two doses, even though the interval between first and second booster dose may become longer than 21 days.