** The CDC’s vaccine prioritization strategy has worked well compared to other approaches, but with some room for improvement.**

The four-tier vaccine prioritization strategy implemented by the U.S. Centers for Disease Control and Prevention (CDC), calculated against all possible COVID-19[female[feminine vaccine deployment approaches, well executed by many measures, but could be improved. The findings are published this week in a new study in the open-access journal PLOS ONE by Md Rafiul Islam and Claus Kadelka of Iowa State University, USA, and their colleagues.

Anticipating an initial vaccine shortage for COVID-19, the U.S. Centers for Disease Control (CDC) developed priority vaccine allocations for specific demographic groups of the population. This prioritization strategy, and its impact on subsequent disease, has been studied in several ways, but generally only compared to a small number of other vaccine deployment strategies at a time.

In the new study, Kadelka and colleagues developed a disease model that divided the U.S. population into 17 subpopulations based on characteristics included in the CDC vaccine recommendation: age, comorbid state, type of employment, and status. of life. There are approximately 17.2 billion ways in total to divide vaccines among these 17 subpopulations into up to four phases. Researchers have found that only 17.5 million can be optimal. They compared these 17.5 million allocation strategies and analyzed the resulting effect on COVID-19 cases, mortality and years of life lost (YLL), using well-established assumptions about incubation and the spread of COVID-19, vaccine reluctance and vaccine efficacy rates.

According to the analysis, the CDC allocation strategy worked well across all immunization goals, but was never ranked the highest of all possible strategies. Compared to the respective optimal methods, the CDC approach resulted in approximately 0.19% more deaths, 4.0% more cases, 4.07% more infections, and 0.97% more YLL raised. Note that there are tradeoffs between vaccination goals so that no single strategy works better in goals: a low number of deaths comes, for example, at the expense of a higher number of cases. The CDC’s decision not to prioritize immunizing people under the age of 16 was optimal, as was the prioritization of healthcare workers and other essential workers. However, it was felt that theoretical strategies that placed greater priority on vaccination of individuals with co-morbidities in all age groups would improve outcomes. The authors believe that this optimization approach can be used to inform the design of future vaccine allocation strategies around the world.

The authors add, “We have developed a model that allows for an accurate assessment of the prioritization of the COVID-19 vaccine in the United States. The model further shows how the choice of the optimal vaccine strategy depends on parameters such as reluctance or the performance of a specific vaccine.

For more on this study, read Did CDC’s COVID-19 Vaccine Strategy Work? Comparison of 17.5 million options.

Reference: “Evaluation of the United States COVID-19 vaccine allocation strategy” by Md Rafiul Islam, Tamer Oraby, Audrey McCombs, Mohammad Mihrab Chowdhury, Mohammad Al-Mamun, Michael G. Tyshenko and Claus Kadelka, November 17, 2021, *PLoS A*.

DOI: 10.1371 / journal.pone.0259700