COVID19 vaccines as boosters or first doses: simulating scenarios to minimize infections and deaths

Public health authorities face the issue of optimal vaccine distribution during the spread of pandemics. In this paper, we study the optimal way to distribute a finite supply rate of COVID-19 doses between either the first or second doses for unvaccinated individuals and the third doses (booster shots) for fully vaccinated individuals. We introduce a novel compartmental model that accommodates the vaccinated populations. This Booster model is implemented to simulate two prototypes of populations: one with a highly infected and highly vaccinated proportion, and another with a lowly infected and lowly vaccinated percentage. We namely use sample data from Russia and Djibouti, respectively.Our findings show that around one quarter of the vaccines should be employed as booster shots and the rest as first and second doses to minimize the deaths for the first type of population. On the other hand, the second type of population can minimize their number of deaths by mainly focusing on administering the initial two doses, rather than giving any booster shots. The novel Booster model allows us to study the effect of the third dose on a community and provides a useful tool to draw public policies on the distribution of vaccines during pandemics.