  To mitigate the pandemic stemming from COVID-19, numerous nations have
initiated extensive vaccination campaigns for their citizens since late 2020.
While affluent countries have predominantly received vaccine allocations, fewer
doses have been dispatched to nations with lower average incomes. This unequal
distribution not only widens the disparity between wealthy and impoverished
regions but also prolongs the pandemic, evident in the emergence of new viral
variants. Our research delves into the correlation between the duration of the
pandemic and the timing of vaccine distribution between two countries with
migratory ties. By using a pair of coupled Susceptible-
Infected-Recovered-Deceased (SIRD) models incorporating vaccination data, we
demonstrate that timely sharing of vaccines benefits both nations, regardless
of the presence of viral variants. This underscores that in the realm of
vaccine distribution, self-interest and altruism are not mutually exclusive.
