Evaluating vaccine allocation studies in LMIC settings: prioritizing COVID-19 vaccination efforts in Madagascar.
The COVID-19 pandemic created an unprecedented global health crisis. Initial mitigation strategies focused on the deployment of non-pharmaceutical interventions to slow the spread of the epidemic. By late 2020, the development of several highly effective vaccines expanded the options for control and public health. While mass COVID-19 vaccination programs are underway in high-income countries, limited availability of doses has resulted in few vaccines administered in low and middle income countries (LMICs). The COVID-19 Vaccines Global Access (COVAX) is a WHO-led initiative to promote vaccine access equity to LMICs and is providing many of the doses available in these settings. However, initial doses will be limited and countries, such as Madagascar, will need to develop prioritization schemes to maximize the benefits of vaccination with very limited supplies. There are many possible strategies for dose deployment including prioritizing health care workers, older individuals and those who are more vulnerable. However, in different settings the trade offs between these options may vary. Further, promoting vaccine access to more rural areas may pose additional logistical challenges, but include substantial proportions of the population. To address these questions, we developed a mathematical model of SARS-CoV-2 transmission dynamics and simulated various vaccination allocation strategies based on a number of possible prioritization schemes. Using deaths due to COVID-19 as the main outcome of interest, our results indicate that distributing the number of vaccine doses according to the number of elderly living in the region or according to the population size results in a greater reduction of mortality compared to distributing limited doses based on the reported number of cases and deaths. At a subnational scale, our results support the strategy adopted by the COVAX initiative at a global scale.