Pursuing equitable access to vaccines for the next epidemic

To end the pandemic caused by the coronavirus disease 2019 (COVID-19), many countries have implemented large scale vaccinations for their nationals since late 2020. Most of the vaccines have been allocated to wealthy countries while few have been sent to countries with lower average income. Unequal distribution of vaccines not only deepens the gap between the rich and poor but also elongates the pandemic, as evidenced by emergent pathogenic variants of the virus. We study the relationship between the pandemic ending time and vaccine allocation time between two countries with mutual migration of peoples. Using two coupled Susceptible-Infected-Recovered-Deceased (SIRD) model with vaccinations, we show that sharing vaccines in time is beneficial to both countries with and without the threat of virus variants. This shows that in the matter of vaccine distribution the self-interest and altruism are not mutually exclusive.Comment: 12 pages, 6 sets of figure