Clinical Report: Vaccine Dose Prioritization in 2022 Mpox Outbreak NYC

Overview

During the 2022 mpox outbreak in New York City, prioritizing single-dose vaccination across a broader population averted more cases than prioritizing full two-dose vaccination for fewer individuals. Modeling estimated that the first-dose priority strategy prevented 66% of potential cases compared to no vaccination, outperforming strategies focusing on second-dose completion.

Background

Mpox cases surged in the US in 2022, with over 30,000 diagnoses and a peak in August. The CDC recommended a two-dose JYNNEOS vaccine series 4 weeks apart for high-risk groups, including GBMSM with multiple partners. However, limited vaccine supply led NYC to adopt a single-dose priority approach to rapidly protect more individuals. This study used a dynamic network transmission model to compare the impact of different vaccine dose prioritization strategies on mpox case reduction.

Data Highlights

Key Findings

• The first-dose priority strategy in NYC averted 66% (IQR 47%-78%) of potential mpox cases compared to no vaccination.
• This strategy averted 0.6% (IQR -11% to 9.8%) more cases than the intermediate strategy prioritizing second doses over first doses.
• It averted 17% (IQR 2.9%-38%) more cases than the second-dose priority strategy that preallocated full vaccine courses to fewer individuals.
• Prioritizing full two-dose vaccination in a smaller population would have increased the outbreak size.
• The model incorporated detailed sexual network dynamics among GBMSM in NYC to simulate transmission and vaccination effects.

Clinical Implications

In outbreak settings with limited vaccine supply, prioritizing widespread administration of a single vaccine dose can more effectively reduce mpox transmission than focusing on completing two-dose series in a smaller group. Rapid expansion of partial immunity in high-risk populations may be critical to outbreak control. These findings support flexible vaccination strategies that maximize first-dose coverage during vaccine shortages.

Conclusion

The NYC experience and modeling data indicate that during the 2022 mpox outbreak, a first-dose priority vaccination approach was more effective at averting cases than strategies emphasizing full two-dose vaccination in a limited population. This approach may inform future mpox vaccination policies under constrained vaccine availability.

References

1. CDC 2022 -- JYNNEOS Vaccine Recommendations for Mpox
2. NYC Health 2022 -- Mpox Vaccination Strategy
3. Mathematical Modeling Studies 2022 -- Vaccine Dose Prioritization Impact
4. WHO 2023 -- Clade I Monkeypox Virus Public Health Emergency