Who Was Left Unvaccinated for Mpox? A Shortfall Analysis, 2022–2023

The 2022 mpox outbreak brought more than 30,000 U.S. cases, falling disproportionately on gay, bisexual and other men who have sex with men (MSM), with large racial and ethnic disparities. The national strategy focused the JYNNEOS vaccine on people at higher risk, and from May 2022 to April 2023, 748,329 first doses (of two) were given.

Early on, coverage lagged among racial and ethnic minority groups; efforts to widen access then raised it. CDC asked whether that progress was equitable — using a shortfall analysis.

Measuring the gap, not the gain

The shortfall is simple: the share of eligible people who have not received a first dose (100% minus coverage). Unlike many disparity measures, it needs no comparison group — each group is measured against 100%. And because a given gain in coverage looks bigger, in relative terms, for a group that started low, the shortfall is a fairer yardstick of progress toward full vaccination.

The eligible population was estimated as MSM with HIV plus MSM with indications for HIV PrEP, increased by 25% to include others at higher risk: other MSM at increased risk, partners of MSM, close contacts of cases, and people with occupational exposure.

Two-thirds still unvaccinated

By the end of April 2023, an estimated 34.0% of the eligible population had a first dose — a shortfall of 66.0%.

Shortfalls and percent decreases in shortfall in first-dose JYNNEOS vaccination, by race and ethnicity. Image from CDC’s report.

Uneven progress

The shortfall shrank for every group, but not equally:

The big gains in August and September may reflect more vaccine supply after dose-sparing intradermal injection was recommended on August 9, 2022, plus expanded efforts focused on disparities. Later reductions were small: 1.6% from October to November, 0.8% to December, 0.5% to January and 0.2% from March to April.

For Black and American Indian or Alaska Native people, reductions were smaller than overall in every month studied, so their shortfalls stayed persistently higher.

Why the Black shortfall is so large

Black people were approximately 20% more likely than White people to be vaccinated — but also approximately 83% more likely to be in the vaccine-eligible population. An earlier report found Black men’s vaccination rate was 1.2 times White men’s, while their mpox incidence was 5.8 times higher. A slightly higher vaccination rate was nowhere near enough.

Closing the gap

The authors call for putting resources and access where shortfalls are largest, working with trusted messengers, community organizations and providers who can shape culturally and linguistically fitting messages. To lower the risk of future outbreaks, coverage must rise substantially among all eligible people — especially the groups furthest behind.

Limits: race and ethnicity were missing for 9% of vaccinated people (counting them would put the overall shortfall at 62.5%); the sizes of the eligible groups are uncertain, as the racial makeup of MSM with PrEP indications was assumed to match U.S. men overall; and the 25% allowance for other eligible people may understate need in some minority groups, so shortfalls there may be underestimated.

Sources

Based on Kota KK, Chesson H, Hong J, et al., "Progress Toward Equitable Mpox Vaccination Coverage: A Shortfall Analysis — United States, May 2022–April 2023," MMWR Vol. 72, No. 23, CDC; a work of the United States government in the public domain.