Smallpox vaccine advised for personnel at risk for orthopox exposure

By Will Boggs MD

NEW YORK (Reuters Health) - The current vaccinia virus smallpox vaccine should be used in laboratory and health care personnel at risk for occupational exposure to orthopoxviruses, according to the Advisory Committee on Immunization Practices (ACIP).

Aside from smallpox, members of this genus that cause infection in humans are vaccinia virus, monkeypox virus, and cowpox virus.

"These recommendations are specific for the current smallpox vaccine ACAM2000, which has replaced the previous vaccine, Dryvax, which is no longer available," Dr. Brett W. Petersen from the Centers for Disease Control and Prevention (CDC), Atlanta, told Reuters Health by email. "The majority of the recommendations remain unchanged."

"There are several updates/revisions," Dr. Petersen said. "For example, the 'highly attenuated' and 'nonhighly attenuated' terminology is replaced by 'replication-competent' and 'replication-deficient' to add clarity and specificity to the vaccination recommendations. Also, the presence of cardiac risk factors is no longer a contraindication for revaccinees."

ACIP now recommends routine vaccination with ACAM2000 for "laboratory personnel who directly handle 1) cultures or 2) animals contaminated or infected with replication-competent vaccinia virus, recombinant vaccinia viruses derived from replication-competent vaccinia strains (i.e., those that are capable of causing clinical infection and producing infectious virus in humans), or other orthopoxviruses that infect humans (e.g., monkeypox, cowpox, and variola)."

Also, the vaccine can be offered to "health care personnel (e.g., physicians and nurses) who currently treat or anticipate treating patients with vaccinia virus infections and whose contact with replication-competent vaccinia viruses is limited to contaminated materials (e.g., dressings) and persons administering ACAM2000 smallpox vaccine who adhere to appropriate infection prevention measures."

Eligible individuals should be revaccinated at least every 10 years if they work with replication-competent vaccinia viruses and recombinant viruses developed from replication-competent vaccinia viruses and every three years if they work with more virulent orthopoxviruses (e.g., variola, monkeypox).

Revaccination is not recommended for those who work with replication-deficient vaccinia viruses and recombinant viruses developed from replication-deficient vaccinia viruses, according to the March 18 Morbidity and Mortality Weekly Report.

ACAM2000 vaccination is contraindicated for individuals with atopic dermatitis or other exfoliative skin conditions, conditions associated with immunosuppression, pregnancy, breastfeeding, serious allergy to a vaccine component, known underlying heart disease, or three or more known major cardiac risk factors.

CDC is the only source of ACAM2000 for civilians.

"I would like physicians to be aware that orthopoxviruses are being increasingly used in biomedical research and that resources are available to guide vaccination and other management decisions," Dr. Petersen said. "CDC is available 24/7 for consultations regarding poxviruses and smallpox vaccine."

SOURCE: http://1.usa.gov/1RfyFln

MMWR 2016.

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