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What is Smallpox and Monkeypox (Mpox) vaccine?

Updated November 03, 2023

There are two smallpox vaccines approved by the U.S. Food and Drug Administration (FDA): ACAM 2000, a live smallpox (vaccinia) vaccine, developed and manufactured by Emergent Product Development Gaithersburg, Inc., and JYNNEOS, a live, non-replicating, smallpox and monkeypox (mpox) vaccine, developed and manufactured by Bavarian Nordic.

A third vaccine, Aventis Pasteur Smallpox Vaccine (APSV), is an unapproved vaccine that has been added to the Strategic National Stockpile (SNS). This investigational vaccine is only available in the event that all stores of ACAM 2000 vaccine have been used, or on a case-by-case bases when ACAM 2000 is contraindicated. 

Smallpox (Vaccinia) Vaccine, Live (ACAM 2000)

ACAM 2000 is a live smallpox (vaccinia) vaccine approved for use in persons considered at a high-risk of smallpox infection. The vaccine is made from plaque purification cloning of the Dryvax® vaccine – a vaccine manufactured by Wyeth Laboratories, (Marietta, PA) and a calf lymph vaccine (New York City Board of Health Strain) and grown in African Green Monkey kidney (Vero) cells.

Ingredients found in ACAM 2000 include HEPES, 2 percent human serum albumin, 0.5 - 0.7 percent sodium chloride USP, 5 percent Mannitol USP, neomycin, polymyxin B, 0.25 percent phenol USP and 50 percent Glycerin USP. 

ACAM 2000 is administered by the percutaneous route (scarification) using 15 jabs of a bifurcated needle and must be given by someone trained on the safe administration of the vaccine. 

The CDC’s Advisory Committee on Immunization Practice (ACIP) recommends ACAM 2000 vaccination for laboratory personnel who directly handle cultures or animals infected or contaminated with vaccinia viruses or other orthopoxviruses that are capable of infecting humans. Health care personnel who treat or who anticipate treating individuals with vaccinia virus infections or who may have contact with the virus due to handling of contaminated materials as well as persons who administer ACAM 2000 may also be offered the vaccine. 

Smallpox and Monkeypox (Mpox) Vaccine, Live, Non-Replicating (JYNNEOS)

JYNNEOS is a live, non-replicating smallpox and monkeypox (mpox) vaccine that received FDA approval for use in adults 18 years of age and older considered at high-risk of smallpox or mpox infection. 

JYNNEOS is a live vaccine made from the Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) strain, an attenuated, non-replicating orthopoxvirus. MVA-BN is grown in Chicken Embryo Fibroblast (CEF) cells in a serum-free medium that does not contain any direct animal material. Additional ingredients include benzonase, tromethamine, sodium chloride, gentamicin, and residual host-cell DNA.

JYNNEOS is recommended to be given subcutaneously as a 2-dose series, 4 weeks apart.  The CDC has authorized use of the vaccine in persons who are at risk of occupational exposure to orthopoxviruses. This includes laboratory personnel working with orthopoxviruses, healthcare providers administering ACAM2000 or those treating individuals with orthopoxvirus infection. Booster doses of the vaccine have also been approved for persons at continued risk of exposure to orthopoxviruses, and this vaccine may be given as a booster dose for persons who received a primary series of ACAM2000. 

On August 9, 2022, the FDA authorized the JYNNEOS vaccine under Emergency Use Authorization (EUA) to be administered intradermally to individuals 18 years and older. Per the FDA, one-fifth of the standard dose can be given intradermally as a two-dose series, 28 days apart. Additionally, the FDA authorized use of the vaccine subcutaneously in persons under the age of 18 who are considered at high-risk for mpox illness. 

In October 2023, the CDC’s Advisory Committee on Immunization Practices (ACIP) voted in favor of an interim recommendation for the use of Jynneous mpox vaccine in all adults 18 years and older who are considered at risk for mpox. Persons considered at risk for mpox include gay, bisexual or other men who have sex with other men, transgender and nonbinary individuals who, in the previous six months, have had at least one of the following: 

  • Sex with more than one person
  • A new diagnosis of one or more sexually transmitted infections
  • Sex in affiliation with a large public event in a region where mpox transmission is occurring
  • Sex at a commercial sex site

This recommendation also includes individuals with sexual partners who meet the above criteria and people who anticipate experiences that place them at risk of mpox. 

IMPORTANT NOTE: NVIC encourages you to become fully informed about smallpox/monkeypox (Mpox) and the smallpox/monkeypox (Mpox) vaccine by reading all sections in the Table of Contents, which contain many links and resources such as the manufacturer product information inserts, and to speak with one or more trusted health care professionals before making a vaccination decision for yourself. This information is for educational purposes only and is not intended as medical advice.

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