Monkeypox in Patient Immunized with ACAM2000 Smallpox Vaccine During 2022 Outbreak

Area of Science:

• Virology
• Epidemiology
• Vaccinology

Background:

• Smallpox vaccination, primarily with ACAM2000, has been a strategy to confer immunity against related orthopoxviruses.
• Monkeypox is a zoonotic viral disease that has emerged globally, posing a public health concern.

Observation:

• A case of monkeypox occurred in the United States in an individual previously vaccinated with ACAM2000 smallpox vaccine eight years prior.
• The patient presented with prodromal symptoms followed by the development of painless, coalescing penile lesions.

Findings:

• The occurrence of monkeypox in a vaccinated individual suggests that prior smallpox vaccination may not provide complete or lifelong protection against infection.
• The clinical presentation included characteristic lesions, indicating active viral replication and disease progression despite vaccination.

Implications:

• This case underscores the importance of continued surveillance for monkeypox, even in vaccinated populations.
• Further research is warranted to understand the duration and efficacy of ACAM2000 immunity against contemporary monkeypox strains.
• Public health strategies may need to adapt to account for potential vaccine breakthrough infections.