Decision Analytic Model Evaluates COVID-19 Vaccine Distribution

Using a decision analytic model, a new study finds that risk-based vaccine prioritization strategies could be the most effective method to reduce the spread of COVID-19 and ensure vaccine distribution equity.

The United States has seen more than 22 million cases of COVID-19 and 400,000 deaths due to the disease. Additionally, COVID-19 has highlighted health inequality in the country as populations facing social disparities have been disproportionately impacted. While the COVID-19 vaccine is the key to controlling the virus, the United States struggled with vaccine supply in early 2021.

It was recommended by the Advisory Committee on Immunization Practices (ACIP) that the United States pursue a COVID-19 vaccine allocation rollout method.

“While the ACIP allocation hierarchy sought to balance exposure risk factors, morbidity, and mortality along with social and equity priorities, implementing this strategy proved challenging, with many states pivoting to alternate approaches like age-based stratification. A key limitation has been the availability of data needed to implement the ACIP guidelines,” the study authors wrote.

Kaiser Permanente researchers worked to determine the association of different vaccine allocation methods with COVID-19 related morbidity and mortality and the distribution by racial and ethnic groups over time.

To accomplish this, the team simulated risk-based, age-based, and Centers for Disease Control and Prevention-phased vaccine allocation strategies using electronic health record data from Kaiser Permanente Northern California’s integrated health care delivery system.

The purpose of the study was to determine the most efficient COVID-19 vaccine allocation strategy to reduce hospitalizations, prevent deaths, and create equitable vaccine distribution, eliminating health disparities.

The study included 3,202,679 adult patients who tested positive for COVID-19 between February 1, 2020, and December 3, 2020. While the researchers studied transmission and death rates of COVID-19, they also examined the vaccination rate among four broad racial and ethnic groups; White, Black, Hispanic, and Asian.

The study created six simulated vaccine strategies with a targeted goal of vaccinating 75 percent of KPNC members in eight months.

Compared to the other two methods, the risk-based strategies showed the largest estimated reductions in nonelective hospitalizations, deaths, and household transmission. By creating COVID-19 risk scores, the researchers determined higher-risk patients and simulated their early vaccination.

“In this simulated modeling study of adults from a large integrated health care delivery system, risk-based strategies were associated with the largest estimated reductions in COVID-19 hospitalizations, deaths, and household transmissions compared with the CDC proxy and age-based strategies, with similar proportions of Hispanic and Black patients being vaccinated early in the process compared with the CDC strategy,” the authors concluded.