COVID-19 infections, hospitalizations, and deaths among black and Hispanic populations have shown how racial and ethnic disparities persist even (or mostly) in the health arena. A study published earlier this week in JAMA network open set out to quantify how vaccination rates differed by race and ethnicity in the United States.

Investigators used a decision analysis model, examining the population distribution by age, self-reported race and ethnicity, and census tract from data provided by the American Community Survey. Until March 31, 2021, they stratified people who had received at least one dose of vaccine by age, and then by self-reported race and ethnicity. Investigators reported estimates for Asian, Black, Hispanic and White populations based on the state-level minimum population threshold of 200,000 people.

Investigators combined all the data to estimate relative immunization rates by race and ethnicity for all eligible adults, defining relative immunization rates as “the observed share of immunizations for a racial or ethnic group divided by the expected share if the catch between racial and ethnic groups within each age group was proportional to the size of the population. The study controlled for the interaction of age-based eligibility criteria with race and ethnicity, attempting to isolate the effects of differing accessibility and reliance on vaccines.

The study modeled vaccine scaling for each census tract in a state under 3 different scenarios: persistent differential uptake, equalized uptake and equalized uptake, and geographic targeting. In the persistent differential uptake scenario, investigators used state-observed daily immunization rates reported to the CDC from April 1 to July 1, 2021, assuming disparities in state-specific relative uptake rates by race and ethnicity would remain consistent.

In the equalized scenario, investigators assumed equal daily vaccination rates across all racial and ethnic groups in each state, defining each day as the highest rate observed for any group with a population of at least 200,000.

In the equalized uptake and geographic targeting scenario, for six weeks after April 1, 2021, investigators modeled the impact of doubling vaccination rates for the most disadvantaged quartile of census tracts, as reported by the CDC Social Vulnerability Index. As of July 1, 2021, investigators compared the hypothetical projections in the 3 scenarios to the estimated actual immunization rate by race and ethnicity to measure progress toward immunization equity.

In most states in the United States, relative absorption rates through March 31, 2021 were significantly higher in white adults than in blacks and Hispanics. The median vaccination rate for white adults was 1.3 times that of black and Hispanic adults. Combining the effects of disproportionate participation and age-based eligibility, investigators estimated that coverage among black and Hispanic adults was one-third (29%) lower than that of white adults ( 43%).

In the persistent differential absorption scenario, Hispanic and black adults would achieve 50% coverage of 1 or more doses of vaccine 57 days and 26 days later, respectively, than white adults. In the equalized absorption scenario, these times were reduced to 17 days for Hispanic adults and 30 days for black adults.

In the matched absorption and geographic targeting scenario, delays in 50% coverage of one or more vaccine doses were hypothetically reduced to 8 days for Hispanic adults and 13 days for black adults. In this scenario, the vaccine disparity between Hispanic and white adults would have been eradicated by July 1, 2021 and reduced to 76% for black adults.

Actual estimates of immunization coverage as of July 1 were 67% for white adults, 68% for Hispanic adults, and 54% for black adults. Actual coverage of black adults reached projected levels in the equalized absorption scenario in only 10 of 30 states with sufficient data and population size, and coverage among Hispanic adults reached these benchmarks in 20 of the 30 states. 27 states analyzed.

Investigators saw these findings as underscoring “the urgent need to invest in policies and interventions to promote equity in vaccines.” Our results also demonstrate the advantages of territorial targeting of efforts to promote the use of vaccination…. “