Dynamic Vaccine Allocation for Control of Human-Transmissible Disease

Abstract

During pandemics, such as COVID-19, supplies of vaccines can be insufficient for meeting all needs, particularly when vaccines first become available. Our study develops a dynamic methodology for vaccine allocation, segmented by region, age, and timeframe, using a time-sensitive, age-structured compartmental model. Based on the objective of minimizing a weighted sum of deaths and cases, we used the Sequential Least Squares Quadratic Programming method to search for a locally optimal COVID-19 vaccine allocation for the United States, for the period from 16 December 2020 to 30 June 2021, where regions corresponded to the 50 states in the United States (U.S.). We also compared our solution to actual allocations of vaccines. From our model, we estimate that approximately 1.8 million cases and 9 thousand deaths could have been averted in the U.S. with an improved allocation. When case reduction is prioritized over death reduction, we found that young people (17 and younger) should receive priority over old people due to their potential to expose others. However, if death reduction is prioritized over case reduction, we found that more vaccines should be allocated to older people, due to their propensity for severe disease. While we have applied our methodology to COVID-19, our approach generalizes to other human-transmissible diseases, with potential application to future epidemics.

Keywords: COVID-19; transmission modeling; vaccine allocation.

Figure 1

A schematic of the SLSQP algorithm.

Figure 2

RRMSE across age groups for COVID-19 cases in all 50 states.

Figure 3

RRMSE across age groups for COVID-19 deaths in all 50 states.

Figure 4

Fitting results of case/death numbers across three age groups for California and New York.

Figure 5

Vaccine allocation comparison for case-prioritized vaccine optimization with original vaccine availability.

Figure 6

Vaccine allocation comparison for death-prioritized vaccine optimization with original vaccine availability.

Figure 7

Redistribution of the original amount of vaccine among 50 states for a case-prioritized scenario (change in the vaccine distribution divided by the original amount of vaccine).

Figure 8

Redistribution of the original amount of vaccine among 50 states for a death-prioritized scenario (change in the vaccine distribution divided by the original amount of vaccine).

Figure 9

Vaccine allocation comparison for case-prioritized vaccine optimization with 10 times the vaccine availability.

Figure 10

Vaccine allocation comparison for death-prioritized vaccine optimization with 10 times the vaccine availability.