Racial and Ethnic Gaps in Mpox Cases and Vaccination Among U.S. Men, 2022

This page summarizes a CDC analysis of the 2022 mpox outbreak. The figures describe that outbreak and are not current.

By December 31, 2022, the United States had recorded 29,939 cases of monkeypox (mpox), 93.3% of them in adult males. From May 10 to December 31, 2022, 723,112 people received the first dose of the two-dose JYNNEOS mpox vaccine, and 89.7% of those doses went to males. The outbreak fell hardest on gay, bisexual and other men who have sex with men (MSM) and on racial and ethnic minority groups.

A team from CDC's Mpox Emergency Response Team asked whether vaccination had kept pace with that uneven burden. Their answer: Black and Hispanic men were vaccinated at higher rates than White men, but nowhere near enough to offset how much more often they were getting sick.

How the analysis worked

The team used case reports that health departments send to CDC and vaccine administration data reported by U.S. jurisdictions, through a system adapted from the one built for COVID-19 vaccines. It looked only at males aged 18 and older, who accounted for the great majority of both cases and doses.

Because the outbreak was concentrated among MSM, rates were calculated per 100,000 MSM. Each group's MSM population was estimated as 3.9% of its adult males, the estimated share of U.S. men who reported having sex with a man in the previous 5 years.

The report focused on Black, Hispanic and White men, who together accounted for more than 88% of cases in males and 83% of doses given to males. It compared the three groups in two ways:

• Rate ratios. Case rates and vaccination rates for Black and for Hispanic men were divided by the rate for White men.
• Vaccination-to-case ratio. A new measure: the number of men in a group who got a first dose in a period, divided by the number of cases in that group in the same period. It shows whether higher vaccination in a group was in proportion to its higher incidence.

Measures were calculated for the whole period and for May–June, July, August, September and October–December (the first and last were combined because counts were low).

What the team found

Cases. From May 10 to December 31, 27,946 cases were reported in adult males: 30.7% in Black men, 29.5% in Hispanic men and 27.9% in White men. Of 648,336 first doses given to adult males, 11.6% went to Black men, 20.6% to Hispanic men and 51.1% to White men.

Incidence was higher among men of every racial and ethnic minority group than among White men, except Asian men, whose rate was similar. Incidence and vaccination both peaked in August for every group, except incidence among White men, which peaked in July; both declined through December. The gap in incidence was widest in August, when the rate among Black men was 6.9 times and among Hispanic men 4.1 times the White rate. It narrowed slightly afterward, but large disparities remained from October to December.

Vaccination. Over the whole period, vaccination rates were generally higher among minority men than among White men, except American Indian or Alaska Native men. Early on it was the other way round: in May–June, Black and Hispanic men were vaccinated at 0.4 and 0.7 times the White rate. By August their rates had passed White men's, at 1.3 and 1.4 times.

The unmet need. Across all groups, 23.8 men were vaccinated for every case over the full period. The ratio was highest among Asian (59.2) and White (42.5) men and lowest among Hispanic (16.2) and Black (8.8) men. All groups' ratios rose from the start of the outbreak to its peak as vaccine became easier to get, but in every period Black and Hispanic men had the lowest ratios.

Top: incidence and first-dose vaccination rate ratios, Black and Hispanic men compared with White men, annotated with milestones in the response. Bottom: vaccination-to-case ratios by group. CDC, MMWR.

Put simply, over the whole period Black and Hispanic men were vaccinated at 1.2 and 1.4 times the White rate, while their incidence was 5.8 and 3.6 times higher. Their higher vaccination did not match their higher risk, leaving a larger unmet need for vaccine.

Why the gaps exist, and what helped

The report points to social determinants of health. Black and Hispanic men may face obstacles to prevention, including gaps in how information reached them, language barriers, racism, homophobia, xenophobia, stigma, discrimination, unemployment and poverty. The tendency to choose sexual partners from within one's own group, linked to wider disparities in sexually transmitted infections such as HIV, may also play a part.

Targeted efforts may explain why vaccination among minority men rose. In September 2022 CDC began an mpox vaccine equity pilot program to reach the communities hit hardest. And the switch to intradermal injection of the vaccine, begun on August 9, 2022, stretched the available supply three- to fivefold, widening access.

Limitations

• Only adult males were studied, so the results may not apply to other groups.
• Race and ethnicity were missing for 6% of patients and 3% of vaccine recipients.
• There was no way to confirm that every man counted as a case or a vaccine recipient was in the MSM population used as the denominator.
• Using a narrower denominator, MSM at higher risk of mpox, could have raised the estimated rates substantially; using all adult males would have lowered them. The authors note that in either case the rate ratios and vaccination-to-case ratios would have been similar.

Conclusion

Disparities in incidence fell slightly toward the end of 2022, possibly thanks to focused public health work, but they had not gone away. The authors called for continued equity-based strategies, such as messages tailored to particular communities and expanded vaccination services for minority groups, and pointed to modeling showing that, at the vaccination coverage of the time, many U.S. jurisdictions were vulnerable to a resurgence of mpox.

Sources

• Kota KK, Hong J, Zelaya C, et al. "Racial and Ethnic Disparities in Mpox Cases and Vaccination Among Adult Males — United States, May–December 2022." MMWR 2023;72(15). https://www.cdc.gov/mmwr/volumes/72/wr/mm7215a4.htm
• The report's summary says 17 Hispanic men were vaccinated per case and its discussion says 16; this page gives the ratio from its results, 16.2. Its results say incidence disparities peaked in August, its discussion in August and September.
• The report acknowledges the work of Dr. Dawn Smith, who died before it was completed.