How to Read a Hospitalization Number
The 2024–2025 U.S. surveillance data add the most consequential outcome to the two-dose JYNNEOS/MVA-BN question: not only whether mpox was diagnosed, but whether the illness led to hospitalization. This chapter explains what the reported counts and adjusted odds ratio show, why the comparison is relevant to vaccination, and why it is still not a personal guarantee. The central skill is to read the numerator, denominator, comparison group, adjustment, and missing data as one result.
Hospitalization sits later in the chain than infection. A person must be exposed, become infected, develop illness severe enough to seek or require care, and then be recorded as hospitalized for mpox. Vaccination can influence more than one step, but a hospitalization table usually observes only the final step among reported cases. That is why a lower hospitalization association can coexist with breakthrough infections and why the number should be interpreted as evidence about severe outcomes, not as a direct measure of whether every exposure was blocked.
The newer surveillance report describes a continuing exposure environment
The CDC report covering 2024 and 2025 counted 5,322 U.S. cases of monkeypox virus infection: 2,803 in 2024 and 2,519 in 2025. Transmission was lower than during the 2022 peak, but it did not disappear. Reported cases approximately doubled from 423 during September and October 2024 to 873 during the same months in 2025, then fell to 448 during November and December 2025. This pattern matters to the vaccine question because a completed series is being used in a setting where people can still encounter the virus.
The report also shows why current case percentages need a denominator and a missingness warning. Vaccination status was reported for 2,049 patients, or 38.5% of the 5,322 cases. Among those with known status, 294 patients—14.3%—were fully vaccinated, 196—9.6%—were partially vaccinated, and 1,559—76.1%—were unvaccinated. Vaccination status was missing for 62% of reported cases. The percentages describe the known-status subset; they cannot be read as the vaccination distribution of every person who had mpox during those two years.
The same report found that hospitalization status was available for 4,635 patients, or 87.0% of reported cases. Among those records, 440 patients, or 9.5%, were hospitalized. Among patients with known vaccination status, 2.0% of vaccinated patients were hospitalized. That figure is a useful descriptive signal, but it is not yet the adjusted comparison. It uses the records with known status, and the report’s more controlled model uses a smaller group with complete information on all variables included in the analysis.
The report describes the vaccinated-case incidence as stable and consistent with expected vaccine performance, and says coverage estimates did not suggest waning of vaccine-conferred immunity. That interpretation should be held at the level of surveillance. The missing vaccination fields, passive case detection, and absence of some immune measurements mean the data cannot show that every vaccinated person had the same protection or that immunity remained biologically constant. They show that the observed case and hospitalization pattern did not produce a clear surveillance signal of collapsing protection.
The report’s definition of full vaccination is also important here. It required two JYNNEOS doses, the second at least 14 days before illness onset, and at least 24 days between the first and second doses.