• Vaccines

Jynneos Generic Name & Formulations

General Description

Smallpox and Monkeypox vaccine, live, non-replicating; contains 0.5–3.95×108 infectious units of MVA-BN live virus; per 0.5mL dose; susp for SC inj; preservative-free.

How Supplied

Single-dose vials—10, 20


  • Keep frozen at -25°C to -15°C (-13°F to +5°F). Store in the original package to protect from light. Do not refreeze a vial once it has been thawed. Once thawed, the vaccine may be kept at +2°C to +8°C (+36°F to +46°F) for 4 weeks. Do not use the vaccine after the expiration date shown on the vial label.


Generic Availability


Mechanism of Action

Jynneos is an attenuated, live, non-replicating smallpox and monkeypox vaccine that elicits humoral and cellular immune responses to orthopoxviruses. Vaccinia neutralizing antibody responses in humans were evaluated to establish the effectiveness of Jynneos for prevention of smallpox and monkeypox.

Jynneos Indications


Prevention of smallpox and monkeypox disease in adults determined to be at high risk for smallpox or monkeypox infection.

Jynneos Dosage and Administration


Give by SC inj (preferably into deltoid). ≥18yrs: 2 doses (0.5mL each) given 4 weeks apart.


<18yrs: not established.

Jynneos Contraindications

Not Applicable

Jynneos Boxed Warnings

Not Applicable

Jynneos Warnings/Precautions


Have appropriate medical treatment available to manage possible anaphylactic reactions. Immunocompromised. Vaccination may not protect all recipients. Pregnancy. Nursing mothers.

Pregnancy Considerations

Risk Summary 

  • Available human data on Jynneos administered to pregnant women are insufficient to inform vaccine-associated risks in pregnancy.

Nursing Mother Considerations

Risk Summary 

  • It is not known whether Jynneos is excreted in human milk.

  • Consider the development and health benefits of breastfeeding along with the mother’s clinical need for Jynneos and any potential adverse effects on the breastfed child from Jynneos or from the underlying maternal condition. 

Pediatric Considerations

  • Safety and effectiveness have not been established in individuals less than 18 years of age.


Geriatric Considerations

  • Clinical studies did not include sufficient numbers of subjects aged 65 and over to determine whether they respond differently from younger subjects.

Jynneos Pharmacokinetics

See Literature

Jynneos Interactions

Not Applicable

Jynneos Adverse Reactions

Adverse Reactions

Inj site reactions (eg, pain, swelling, redness, induration, itching), muscle pain, headache, fatigue, nausea, chills; severe allergic reactions.

Jynneos Clinical Trials

Clinical Trials

Vaccine Effectiveness

  • Vaccine effectiveness against smallpox was inferred by comparing the immunogenicity of Jynneos to a licensed smallpox vaccine (ACAM2000) based on a Plaque Reduction Neutralization Test (PRNT) using the Western Reserve strain of vaccinia virus and was supported by efficacy data from animal challenge studies. 

  • Vaccine effectiveness against monkeypox was inferred from the immunogenicity of Jynneos in a clinical study and from efficacy data from animal challenge studies. 

Immunogenicity – (Study 7)

  • The randomized, open-label study was conducted at US military facilities in South Korea. The study compared the immunogenicity of Jynneos to ACAM2000 in healthy smallpox vaccine-naïve 433 adults 18 through 42 years of age. Patients were randomly assigned 1:1 to receive 2 doses of Jynneos (28 days apart) or 1 dose of ACAM2000.

  • The primary immunogenicity endpoint was geometric mean titer (GMT) of vaccinia neutralizing antibodies assessed by PRNT at “peak visits” defined as two weeks after the second dose of JYNNEOS and four weeks after the single dose of ACAM2000.

  • The GMT of vaccinia neutralizing antibodies assessed post-vaccination at “peak visits” for Jynneos was 152.8 vs 84.4 for ACAM2000.

  • The PRNT GMTs at two and four weeks after the first dose of Jynneos (prior to the second dose), were 23.4 (95% CI: 20.5, 26.7) and 23.5 (95% CI: 20.6, 26.9), respectively. The PRNT GMT at two weeks after the single dose of ACAM2000 was 23.7 (95% CI: 20.9, 26.8).

Jynneos Note

Not Applicable

Jynneos Patient Counseling

Patient Counseling

  • Inform vaccine recipient of the potential benefits and risks of vaccination with Jynneos. 

  • Inform vaccine recipient of the importance of completing the two dose vaccination series. 

  • Advise vaccine recipient to report any adverse events to their healthcare provider or to the Vaccine Adverse Event Reporting System at 1-800-822-7967 and www.vaers.hhs.gov.