Vaccination

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Vaccines

Two vaccines may be used for the prevention of monkeypox disease:

  • JYNNEOS vaccine is used for the prevention of smallpox and monkeypox disease among people determined to be at high risk for infection.
  • ACAM2000 vaccine is approved for immunization against smallpox disease for people determined to be at high risk for infection. It has been made available for use against monkeypox in the current outbreak.

JYNNEOS is a third-generation vaccine based on a live, attenuated non-replicating orthopoxvirus, Modified Vaccinia Ankara (MVA). MVA is a live virus that does not replicate efficiently in humans. JYNNEOS is known internationally as Imvamune or Imvanex, and is manufactured by Bavarian Nordic.

The U.S. Food and Drug Administration (FDA) has issued an Emergency Use Authorization (EUA) in August 2022 to allow for use of JYNNEOS vaccine:

  • By intradermal injection for prevention of monkeypox disease in individuals 18 years of age and older determined to be at high risk for monkeypox infection, and
  • By subcutaneous injection for prevention of monkeypox disease in individuals younger than 18 years of age determined to be at high risk for monkeypox infection.

ACAM2000 is a second-generation vaccine indicated for the prevention of smallpox disease. It has been made available for use against monkeypox in the current outbreak under an Expanded Access Investigational New Drug (EA-IND) protocol, which requires informed consent along with completing additional forms. ACAM2000 contains a live vaccinia virus that is replication-competent in humans. ACAM2000 is manufactured by Emergent BioSolutions.

Available evidence supporting the use of smallpox vaccine for monkeypox prevention is derived from the vaccine used during smallpox eradication, Dryvax. Dryvax was a first-generation smallpox vaccine manufactured by Wyeth laboratories that is no longer available. Routine use of this vaccine was stopped in 1972 after smallpox was eradicated from the United States. The license was withdrawn in 2008 and no supplies of this vaccine remain.

The United States has a large supply of ACAM2000, but this vaccine has more side effects and contraindications than JYNNEOS.

Because of its safety profile, JYNNEOS vaccine should be prioritized for people who are at high risk for severe disease caused by infection with the Monkeypox virus (including, but not limited to, people with human immunodeficiency virus (HIV) infection or other immunocompromising conditions, who are pregnant, or who are at increased risk for serious adverse events following ACAM2000 vaccination).

Components of the U.S. National Monkeypox Vaccination Strategy

The U.S. national monkeypox vaccine strategy was announced on June 28, 2022. Multiple federal agencies, including the Administration for Strategic Preparedness and Response (ASPR)U.S. Food and Drug Administration (FDA)National Institutes of Health (NIH), and Centers for Disease Control and Prevention (CDC) are coordinating to implement this national vaccination strategy.

People can be vaccinated after known or presumed exposure to someone with monkeypox [i.e., post-exposure prophylaxis (PEP)], ideally within four days. Additionally, people with certain risk factors and recent experiences that might make them more likely to have been recently exposed to monkeypox can be considered for vaccination [i.e., expanded post-exposure prophylaxis (PEP++)]. Jurisdictional vaccination programs should reflect national priorities to employ PEP and PEP++ approaches, and should prioritize delivering PEP first, before other vaccination approaches. When combined with other prevention measures including behavior change as described below, PEP and PEP++ might help control outbreaks by reducing transmission of Monkeypox virus, preventing disease, or reducing severity of disease.

Currently, CDC is not recommending routine immunization (or pre-exposure prophylaxis, PrEP) against monkeypox for the general public. Available data from the current outbreak indicate that specific populations are being impacted, and therefore vaccination efforts should remain focused. Guidance from the Advisory Committee on Immunization Practices that predate the current U.S. outbreak recommends PrEP for research laboratory personnel working with orthopoxviruses, clinical laboratory personnel performing diagnostic testing for orthopoxviruses, and orthopoxvirus and health care worker response teams designated by appropriate public health and antiterror authorities. During the current outbreak, in jurisdictions where PEP and PEP++ are being implemented and local supply is available, PrEP has been provided for individuals at increased risk for exposure to monkeypox.

To have the greatest impact on the current outbreak, jurisdictions implementing PrEP should decide on which populations to focus their efforts based on potential for exposure to monkeypox, local epidemiology, population needs, and feasibility based on available vaccine supply.

Monkeypox PrEP should be offered to people with the highest potential for exposure to monkeypox such as:

  • Gay, bisexual, and other men who have sex with men, transgender or nonbinary people who in the past 6 months have had
    • A new diagnosis of one or more nationally reportable sexually transmitted diseases (i.e., acute HIV, chancroid, chlamydia, gonorrhea, or syphilis)
    • More than one sex partner
  • People who have had any of the following in the past 6 months:
    • Sex at a commercial sex venue
    • Sex in association with a large public event in a geographic area where monkeypox transmission is occurring
  • Sexual partners of people with the above risks
  • People who anticipate experiencing the above risks

To be most effective, monkeypox vaccination, including monkeypox PrEP for people with the highest potential for exposure to monkeypox, should be part of broader prevention activities. Such efforts should have health equity principles as a foundation and include strategies such as allowing individuals to self-attest to being eligible to receive vaccine (e.g. providing monkeypox vaccine PrEP without requiring individuals to specify which criterion they meet), community outreach, holding vaccination events on-site in locations where groups of people disproportionately impacted by monkeypox may convene, education efforts, and communication about behavioral strategies to minimize risk. Monkeypox vaccination strategies are likely to be most effective when designed and implemented in partnership with communities and groups that are disproportionately affected. As the epidemiology of the outbreak evolves and new data become available, interim guidance on monkeypox vaccine PrEP will be updated.

Table 1. Components of the U.S. National Monkeypox Vaccination Strategy Used in the U.S. Monkeypox Outbreak

Component

Component

Component

Definition

Definition

Definition

Eligible Populations

Eligible Populations

Eligible Populations

Post-Exposure Prophylaxis (PEP)

Component

Post-Exposure Prophylaxis (PEP)

Vaccination after known exposure to monkeypox

Definition

Vaccination after known exposure to monkeypox

  • People who are known contacts to someone with monkeypox who are identified by public health authorities, for example via case investigation, contact tracing, or risk exposure assessment
Eligible Populations
  • People who are known contacts to someone with monkeypox who are identified by public health authorities, for example via case investigation, contact tracing, or risk exposure assessment

Expanded Post-Exposure Prophylaxis (PEP++)

Component

Expanded Post-Exposure Prophylaxis (PEP++)

Vaccination after known or presumed exposure to monkeypox

Definition

Vaccination after known or presumed exposure to monkeypox

  • People who are known contacts to someone with monkeypox who are identified by public health authorities, for example via case investigation, contact tracing, or risk exposure assessment
  • People who are aware that a recent sex partner within the past 14 days was diagnosed with monkeypox
  • Certain gay, bisexual, or other men who have sex with men, or transgender or nonbinary people, who have had any of the following within the past 14 days: sex with multiple partners (or group sex); sex at a commercial sex venue; or sex in association with an event, venue, or defined geographic area where monkeypox transmission is occurring
Eligible Populations
  • People who are known contacts to someone with monkeypox who are identified by public health authorities, for example via case investigation, contact tracing, or risk exposure assessment
  • People who are aware that a recent sex partner within the past 14 days was diagnosed with monkeypox
  • Certain gay, bisexual, or other men who have sex with men, or transgender or nonbinary people, who have had any of the following within the past 14 days: sex with multiple partners (or group sex); sex at a commercial sex venue; or sex in association with an event, venue, or defined geographic area where monkeypox transmission is occurring

Pre-Exposure Prophylaxis (PrEP)

Component

Pre-Exposure Prophylaxis (PrEP)

Vaccination before exposure to monkeypox

Definition

Vaccination before exposure to monkeypox

  • People in certain occupational exposure risk groups*
  • Gay, bisexual, and other men who have sex with men, transgender or nonbinary people who in the past 6 months have had
    • A new diagnosis of one or more nationally reportable sexually transmitted diseases (i.e., acute HIV, chancroid, chlamydia, gonorrhea, or syphilis)
    • More than one sex partner
  • People who have had any of the following in the past 6 months:
    • Sex at a commercial sex venue
    • Sex in association with a large public event in a geographic area where monkeypox transmission is occurring
  • Sexual partners of people with the above risks
  • People who anticipate experiencing the above risks
Eligible Populations
  • People in certain occupational exposure risk groups*
  • Gay, bisexual, and other men who have sex with men, transgender or nonbinary people who in the past 6 months have had
    • A new diagnosis of one or more nationally reportable sexually transmitted diseases (i.e., acute HIV, chancroid, chlamydia, gonorrhea, or syphilis)
    • More than one sex partner
  • People who have had any of the following in the past 6 months:
    • Sex at a commercial sex venue
    • Sex in association with a large public event in a geographic area where monkeypox transmission is occurring
  • Sexual partners of people with the above risks
  • People who anticipate experiencing the above risks

*People at risk for occupational exposure to orthopoxviruses include research laboratory personnel working with orthopoxviruses, clinical laboratory personnel performing diagnostic testing for orthopoxviruses, and orthopoxvirus and health care worker response teams designated by appropriate public health and antiterror authorities. (see ACIP recommendations).

Timing of Post-exposure Prophylaxis

CDC recommends initiating vaccination within 4 days following the date of exposure for the best chance to prevent onset of the disease.

If initiated between 4 and 14 days following the date of exposure, vaccination might be less effective. Benefits might still outweigh risks when administering vaccine more than 14 days after exposure in some clinical situations (e.g., for a severely immunosuppressed person with a recent sex partner confirmed to have monkeypox).

Vaccination given after the onset of signs or symptoms of monkeypox is not expected to provide benefit.

Planning Considerations for Health Departments and Providers

Vaccine Access Considerations

  • Both vaccines are available from the Strategic National Stockpile (SNS) by jurisdictional request
  • Potential adult or pediatric use of ACAM2000 and potential pediatric use of JYNNEOS should be considered in consultation with CDC
  • Either JYNNEOS or ACAM2000 can be used in accordance with the national vaccination strategy (e.g., for PEP, PEP++, or PrEP), following risk-benefit discussions and a review of any conditions that could increase risk for serious adverse events
  • When developing vaccine distribution plans, jurisdictions should consider the current epidemiology of the outbreak as well as health equity considerations
  • When developing vaccine distribution plans, jurisdictions should plan for and if feasible, schedule, second doses

Health Equity Considerations

  • Engage people from affected communities in planning for vaccine programs and as trusted sources of information about both monkeypox disease and vaccination
  • Use non-stigmatizing, plain language in all forms of communication (e.g., printed materials and in-person communication), in the preferred language of the individual
  • Reduce barriers to vaccination by allowing individuals to self-attest to meeting criteria to receive monkeypox PrEP (i.e., provide monkeypox PrEP without requiring individuals to specify which criterion they meet)
  • Have both subcutaneous and intradermal vaccine administration options available on site so that those unable to receive the intradermal regimen can receive the subcutaneous regimen
  • Reiterate privacy of information and how data will be used, and who will have access to data
  • Engage diverse partners already working with affected populations
  • Bring vaccines to where affected populations live and work through pop-up events and mobile outreach conveniently located in their communities and neighborhoods
  • Offer multiple appointment times and flexible walk-in opportunities, including on evenings and weekends, to improve vaccine accessibility
  • Leverage clinical venues (e.g., Federally Qualified Health Centers) that serve people who have historically had less access to primary care, including sexual health clinics, transgender health clinics, and pharmacies
  • Use multiple channels, such as, social media, websites, television/radio announcements, or flyers to advertise and book appointments
  • Implement equity interventions that prioritize populations less able to access vaccine (e.g., low income or rural communities) even if a first-come, first-served model is used