  The Covid-19 pandemic revealed the difficulties of vaccinating a population
under the circumstances marked by urgency and limited availability of doses
while balancing benefits associated with distinct guidelines satisfying
specific ethical criteria (J.W. Wu, S.D. John, E.Y. Adashi, Allocating Vaccines
in the Pandemic: The Ethical Dimension, The Am. J. of Medicine V.33(11): 1241 -
1242 (2020)). We offer a vaccination strategy that may be useful in this
regard. It relies on the mathematical concept of envy-freeness. We consider
finding balance by allocating the resource among individuals that seem to be
heterogeneous concerning the direct and indirect benefits of vaccination,
depending on age. The proposed strategy adapts a constructive approach in the
literature based on Sperner`s Lemma to point out an approximate division of
doses guaranteeing that both benefits are optimized each time a batch becomes
available. Applications using data about population age distributions from
diverse countries suggest that, among other features, this strategy maintains
the desired balance throughout the entire vaccination period.
