Note: Because of the potential seriousness of this disease, the Centers for Disease Control and Prevention (CDC) has developed interim guidance to balance the risks of smallpox vaccination against the risks posed by exposure to monkeypox infection. This interim guidance will be re-evaluated as more information becomes available.
Smallpox vaccine for controlling outbreaks of monkeypox would be available under an investigational new drug (IND) protocol sponsored by CDC.
General Recommendations
It is important that vaccinators, as currently occurs in the pre-event smallpox vaccination program, screen potential vaccinees for precautions and contraindications to smallpox vaccination and evaluate vaccination sites for a successful vaccination (i.e., a major reaction
at the site 6-8 days after vaccination). Persons without a successful vaccine take should be revaccinated within 2 weeks of the most recent exposure to monkeypox. State and local health departments should provide information on how vaccinees should seek consultation on evaluation of vaccination sites for major reactions or for potential complications of vaccination.
Rash illnesses suspected to be monkeypox should be confirmed by laboratory evaluation, which, in addition to determining the presence of monkeypox, should have the capability to detect varicella, vaccinia
and other relevant viruses. Laboratory confirmation of monkeypox cases is particularly important before recommending vaccination to persons with close or intimate contact with a monkeypox case and considered to have contraindications to smallpox vaccination in the pre-event smallpox vaccination (e.g., pregnant women, persons with eczema, and children aged <1 year). Intimate contact refers to contact resulting in exposure to body fluids or lesions of ill persons or ill animals. The period of communicability (i.e., exposure period for contacts) for humans may be from 1 day before onset of rash up to 21 days after
rash or illness onset or when all rash lesions have scabbed over. The period of communicability (i.e., exposure period for contacts) for animals may be from 1 day before onset of illness up to 21 days after rash or illness onset or when the ill animal is removed from possible exposure with the contact, or when the animal’s clinical illness ends and all rash lesions have scabbed over. As general guidance, for purposes of smallpox exposure (for human-to-human transmission), close contact has been defined as >3 hours of direct (face-to-face) exposure within 6 feet; this is reasonable guidance for exposure to monkeypox from humans as well. In animal care settings, close contact has been defined as direct exposure within 6 feet of an animal suspected to have monkeypox with respiratory symptoms such as nasal discharge, cough, or conjunctivitis in a setting where the animal has been manipulated (e.g., an exam room). However, judgment must be applied to determine the significance of contact in individual exposure situations.
Who Should be Vaccinated?
- Investigators of suspected human or animal monkeypox
Ideally investigators of suspected monkeypox cases should have
received smallpox vaccination within the past 1-3 years. When possible, priority should be given to using investigators, veterinarians, and animal control personnel who previously were vaccinated and who had a confirmed take. Ideally the vaccination site should have crusted over before deployment. However, if this is not feasible these individuals may be vaccinated immediately before deploying for the field investigation. Unvaccinated investigators currently involved in field investigations or who have been recently involved in such work should be vaccinated as soon as possible, preferably within 4 days from initial direct exposure. Any investigator with an active vaccination site that is not healed should follow the precautions advised for health care workers (HCWs) with regard to the vaccination site care to avoid potential contamination of field samples or of transmission of vaccinia to others.
Field investigators of suspected cases of monkeypox should observe recommended standard, contact, and air-borne infection control precautions even if vaccinated. These include the use of recommended personal protection equipment (currently N95 or comparable respirator) when appropriate. Interim guidance for infection control and exposure management in the health-care and community setting for patients with possible monkeypox virus infection.
- Health Care Workers (HCWs)
- Previously or currently exposed HCWs: HCWs currently caring for confirmed monkeypox cases or who have been recently involved in such
care should be vaccinated. Vaccination should occur as soon as possible after confirmed exposure. Vaccination is recommended for persons who are within 4 days of initial direct (intimate or close) exposure and should be considered only for persons who are within 2 weeks of most recent exposure. Vaccination sites should be managed as recommended for HCWs in the pre-event smallpox vaccination program. Persons without a vaccine take by day 7 should only be revaccinated if within 2 weeks of most recent exposure.
- HCWs who may be asked to care for monkeypox patients in the future: Ideally, HCWs selected to care for suspected monkeypox cases should not have any of the contraindications to smallpox vaccination in the pre-event smallpox vaccination setting. When possible, priority should be given to having HCWs who were previously vaccinated, with confirmed takes, care for patients with suspected monkeypox. When such workers are unavailable, HCWs may be vaccinated immediately prior to beginning their clinical care duties. Vaccination sites should be managed as recommended for HCWs in the pre-event vaccination program.
HCWs who care for suspected cases of monkeypox should continue to observe recommended standard, contact, and air-borne infection control precautions including use of personal protective equipment (currently N95 or comparable respirator) when appropriate, even if vaccinated.
- Contacts
Close contacts, defined as household contacts as well as others who have had close or intimate contact with confirmed human cases, and who are within 4 days of initial direct exposure to a monkeypox case should be vaccinated. Vaccination should be considered for persons who are within 2 weeks of most recent exposure. As general guidance, for purposes of smallpox exposure, close contact has been defined as > 3 hours of direct exposure within 6 feet and this is reasonable guidance for monkeypox exposure as well. Intimate contact refers to contact resulting in exposure to body fluids or lesions of affected persons. However, judgment must be applied to determine the significance of contact in individual exposure situations. State and local health departments should be consulted regarding decisions about vaccination of contacts, and in particular be consulted for contacts who may not meet the strict definitions of close or intimate contact above, especially in child care, school, or health care settings.
Vaccination sites should be managed as recommended for HCWs in the pre-event smallpox vaccination program. Persons who care for recently vaccinated children should be particularly vigilant to observe recommended standard and contact infection control precautions with the vaccination site. Persons without a vaccine take by day 7 should only be revaccinated if within 2 weeks of most recent exposure.
- Persons who have been exposed to a recently acquired prairie dog or other small mammals from implicated distributors
Smallpox vaccination should be recommended for persons who have, within the past 4 days, had direct physical (intimate) contact with ill prairie dogs or other ill small mammals meeting the probable or confirmed case definitions for monkeypox from implicated distributors acquired since April 15 within the affected areas. The interim case definition for animal cases of monkeypox. Vaccination should be considered for persons who are within 2 weeks of most recent exposure. In addition, vaccination can be considered for persons who have close contact with an ill animal that meets the probable or confirmed animal case definition. Close contact is defined as
direct exposure within 6 feet of a probable or confirmed monkeypox case
in an animal with respiratory symptoms such as nasal discharge, cough, or conjunctivitis in a setting where the animal has been manipulated (e.g., an exam room). Smallpox vaccination is not recommended for persons exposed to a healthy animal.
These recommendations may change should evidence show that other symptomatically ill small mammals pose significant risk for human monkeypox.
Vaccination sites should be managed as recommended for HCWs in the
pre-event smallpox vaccination program. Persons who care for recently vaccinated children should be particularly vigilant to observe recommended standard and contact infection control precautions with the vaccination site. Persons without a vaccine take by day 7 should only be revaccinated if within 2 weeks of most recent exposure.
Veterinary health care workers should observe recommended infection control practices including use of personal protective equipment when appropriate, even if vaccinated. It is anticipated that fit-tested N95 respirators will not be available in most veterinary facilities; when currently N95 or comparable respirators are unavailable, surgical masks should be worn to protect against transmission through contact or large droplets. Exposed veterinarians and staff without N95 (or comparable) respirator protection who have direct or close contact to animals with monkeypox should be vaccinated according to the guidelines. Interim guidance for infection control and exposure management in the health-care and community setting for patients with possible monkeypox virus infection.
Interim guidance on appropriate handling of routine clinical laboratory specimens from animals suspected or confirmed to be infected with monkeypox.
Contraindications to Smallpox Vaccination (Refer to the "Contraindications" field)
Vaccinia Immune Globulin (VIG)
No data are available on the effectiveness of VIG in treatment of monkeypox complications. VIG has no proven benefit in the treatment of smallpox complications. It is unknown whether a person with severe monkeypox infection will benefit from treatment with VIG, however, its use may be considered in such instances. VIG can be considered for prophylactic use in an exposed person with severe immunodeficiency in T-cell function for whom smallpox vaccination following exposure to monkeypox is contraindicated.
Cidofovir
No data are available on the effectiveness of cidofovir in treatment of human monkeypox cases. However, cidofovir has proven anti-monkeypox viral activity in in vitro and in animal studies. It is unknown whether a person with severe monkeypox infection will benefit from treatment with cidofovir, however, its use may be considered in such instances. Cidofovir has significant toxicity and should only be considered for treatment of severe monkeypox infections, not for prophylactic use.
Clinical consultation on the use of VIG and cidofovir is available from staff at each state health department in the affected states. In addition, clinical consultation is available from staff at the CDC.
Vaccination of Veterinarians, Veterinary and Animal Control Staff
Similar to health care workers, at this time pre-exposure smallpox vaccination is not recommended for unexposed veterinarians, veterinary staff, and animal control officers in the affected areas, but routine use of appropriate standard, contact and air-borne infection control
measures should be stressed.
Persons who may be involved in field investigations involving potentially infected animals should be vaccinated in advance. This recommendation will be re-evaluated as more information becomes available.
Laboratory workers (e.g., veterinary pathologists) at designated reference laboratories who handle specimens from ill prairie dogs or other ill small mammals meeting the probable or confirmed case definitions for monkeypox from implicated distributors acquired since April 15 within the affected states should be vaccinated as recommended for field investigators or health care workers anticipated to have future contact with suspected monkeypox cases.
Reporting of Adverse Events Associated with Smallpox
Vaccination
Serious adverse events after smallpox vaccination should be reported to the Vaccine Adverse Event Reporting System (VAERS). Refer to the original guideline document for details.
