Vaccine Info

JYNNEOS (MVA-BN) Smallpox Mpox Vaccine

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Last reviewed
December 8, 2023

JYNNEOS® (MVA-BN®) Smallpox Mpox Vaccine

Bavarian Nordic JYNNEOS® (MVA-BN®, IMVAMUNE®) vaccine is based on a live, attenuated vaccinia virus, Modified Vaccinia Ankara (MVA), incapable of replicating in the human body yet able to elicit a potent immune response. The MVA is cultured in Chicken Embryo Fibroblast cells and a serum-free medium. It is purified and filtered from the cells using various methods, including benzonase digestion. JYNNEOS was codeveloped with the U.S. Government  (BARDA, BioShield) to ensure adult populations can be protected from smallpox, including people with weakened immune systems or at high risk of adverse reactions to traditional smallpox vaccines based on replicating vaccinia virus strains.

The U.S. Food and Drug Administration (FDA) granted Bavarian Nordic a Priority Review Voucher under the Material Threat Medical Countermeasure PRV program, accelerating the FDA's drug application review. The FDA approved the two-dose JYNNEOS on September 24, 2019, and it is now indicated for preventing smallpox and mpox diseases. In November 2021, the U.S. Centers for Disease Control and Prevention (CDC) vaccine committee unanimously voted for JYNNEOS as an alternative to the ACAM2000 vaccine for primary and booster doses.

On August 9, 2022, the FDA announced it issued an emergency use authorization (EUA) STN: 125678 for JYNNEOS, enabling healthcare providers to administer it by intradermal injection for individuals at high risk for human monkeypox virus (hMPXV). The CDC announced on February 22, 2023, the Interim Clinical Considerations (ICC): Mpox vaccination should continue to be offered to people with the highest potential for exposure to mpox. On March 15, 2023, the U.S. FDA updated JYNNEOS - STN: BL 125678/20. ATC code: J07BX, and the Approval Letter STN: BL 125678/36. An updated U.S. National Mpox Vaccination Strategy was published on February 6, 2023. As of 2023, JYNNEOS is the only FDA-approved non-replicating smallpox and mpox vaccine for military and non-military use.

On June 23, 2023, Agam Rao, MD CAPT, U.S. Public Health Service, presented: Considerations for long-term protection against mpox - prefers no CDC recommendation for third JYNNEOS dose, including persons with advanced HIV or other severe immunocompromised immune systems. On August 18, 2023, the CDC's Morbidity and Mortality Weekly Report stated that all adults at risk for mpox should receive the JYNNEOS vaccine, regardless of childhood smallpox vaccination status. A case-series (67) study published by The Lancet Infectious Diseases on September 4, 2023, confirmed natural immunity and vaccine-induced immunity are not fully protective against mpox infection.

Surveillance data reported by the CDC on September 8, 2023, and collected by the California Department of Public Health, calculated the odds of hospitalization among persons with mpox who had received 1 or 2 JYNNEOS doses were 0.27 (95% CI = 0.08–0.65) and 0.20 (95% CI = 0.01–0.90), respectively, compared with unvaccinated mpox patients. In mpox patients with HIV infection, the odds of hospitalization among those who had received 1 JYNNEOS vaccine dose was 0.28 (95% CI = 0.05–0.91) times that of those who were unvaccinated. No mpox-associated hospitalizations were identified among persons infected with HIV who had received 2 JYNNEOS vaccine doses. Because the JYNNEOS vaccine is not 100% effective, as more persons are vaccinated, the number of infections occurring in vaccinated persons will likely increase, says the CDC.

A study published by The Lancet Infectious Disease on October 11, 2023, attempted to answer questions regarding the durability and strength of protection following infection and JYNNEOS vaccination. This analysis reported that people vaccinated with MVA-BN were found to develop frequently low or medium mpox neutralizing antibodies compared to infected individuals, as reported in 2023. Ten percent of vaccinated individuals showed no detectable neutralizing antibodies at six months, whereas every person with mpox infection developed antibodies. People living with HIV, when compared with people without HIV, developed more frequently low or medium-neutralizing antibody responses, which might be related to premature cellular senescence.

The CDC's Advisory Committee on Immunization Practices voted on October 25, 2023, to recommend the routine use of JYNNEOS®, the Company's FDA-approved smallpox vaccine, in adults at risk of smallpox or mpox infection. The Standing Committee for Vaccination in Germany endorsed a similar recommendation in 2022. The European AIDS Clinical Society also recommends the vaccine for adults infected with HIV or on preexposure prophylaxis treatment, and it may support additional national recommendations for the vaccine in the future.

On December 7, 2023, the CDC published a Health Alert Network Health Advisory stating Vaccines (JYNNEOS) are expected to be effective for both Clade I and Clade II MPXV infections. The JYNNEOS smallpox vaccine is expected to have similar vaccine effectiveness against MPXV clade I, as seen with clade II. However, real-world data is lacking, reported the ECDC in December 2023. 

Demographic subgroup information is available in Section 1.1 of the Clinical Review Memo for information about participation in the clinical trials and any notable analysis of demographic subgroup outcomes. And Section 6.2 (Postmarketing Experience) to the Package Insert.

Bavarian Nordic A/S is headquartered in Kvistgaard, Denmark (OTCMKTS: BVNRY) (OMX: BAVA), which focuses on developing, manufacturing, and commercializing life-saving vaccines.

JYNNEOS Availability 2023

Pending approval, Bavarian Nordic is targeting a commercial launch of JYNNEOS in the U.S. in the first half of 2024. On August 3, 2023, Bavarian Nordic announced it would manufacture and supply additional liquid-frozen doses of JYNNEOS to the U.S. government in 2023, valued at USD 3 million. Additionally, on August 3, 2023, Bavarian Nordic A/S announced BARDA placed a new order valued at USD 120 million, primarily covering the manufacturing of new bulk product for the JYNNEOS smallpox/mpox vaccine.  

As of 2023, about 1,257,943 doses had been administered in 57 U.S. Jurisdictions. As November 2023, JYNNEOS vaccinations been administered in cities such as American Samoa,   AnchorageAtlantaAustin, Baltimore, BirminghamBosieBoston, CaliforniaChicago, Connecticut,   Dallas,   Denver, GuamHouston, LaramieLittle RockLos AngelesMiami, New OrleansNew York City, OrlandoPheonixPhiladelphia, Pittsburg, PortlandSan AntonioSan Francisco, Washington DC, and Wilmington Del. In New York, NYCDOHMH receives the Jynneos vaccine directly from the federal government, distributing it within their jurisdiction. For more information on New York City, please visit this linkNew York City announced on September 13, 2022, that it would offer Jynneos vaccine second doses to people (3,402) who received their first dose on or before July 23, 2022. On October 3, 2022, the U.S. HHS published a Public Readiness and Emergency Preparedness Act declaration in the Federal Registry that grants pharmacists certain authorities to administer mpox vaccines. Since 2003, Bavarian Nordic has worked with the U.S. government on developing, manufacturing, and supplying a non-replicating smallpox vaccine. On August 29, 2022, HHS announced it would provide approximately $11 million to support the manufacturing of Jynneos in Grand Rapids, Michigan.

MVA-BN® Global Availability

Bavarian Nordic A/S was awarded a contract on September 13, 2023, to supply its MVA-BN smallpox vaccine to rescEU, a strategic reserve within the European Union (EU). This new order follows an initial contract awarded in June 2023 and is also for delivery in 2024. rescEU was established as a reserve of European capacities, including medical items. As of 2023, the MVA-BN (Jynneos, IMVANEX, MVAMUNE) vaccine was available in Australia,   BrazilCanada, the CaribbeanCyprus, the Democratic Republic of CongoDenmarkEuropeFrance, Germany, Iceland, IndonesiaIsreal, ItalyMexicoNigeria, Norway, PortugalScotlandSpain, Taiwan, and the U.K. The U.K. NHS mpox outbreak vaccination program is now only available in London. The U.K. Health Security Agency is making second doses available. Mpox vaccination appointments are available using this NHS vaccine finder. As of August 7, 2023, a total of 77,809 mpox vaccination services have been completed in Taiwan, including 447 post-exposure prophylaxis vaccinations and 77,362 preexposure prophylaxis vaccinations. MVA-BN (IMVANEX®) was authorized by the European Medicines Agency (EMEA/H/C/002596) in 2013.

IMVAMUNE® Availability

Since May 2022, the Canadian government has deployed over 145,000 vaccine doses of IMVAMUNE®. Health Canada has approved the vaccine for use against mpox and smallpox.

JYNNEOS Vaccine Efficacy 2023

Post-exposure prophylaxis (PEP) and pre-exposure prophylaxis (PrEP) by vaccination were offered during the mpox outbreak in May 2022. On September 8, 2023, the U.S. CDC confirmed the JYNNEOS vaccine is not 100% effective. The CDC's ACIP reported in October 2023 JYNNEOS Vaccine Effectiveness (VE) against mpox ranges from 36%–75% for 1-dose vaccination and 66%–89% for 2-dose vaccination. VE trended higher for immunocompetent participants compared to self-reported immunocompromised participants. The Lancet Infectious Disease reported that the JYNNEOS (MVA-BN) vaccine showed an effectiveness of 66–78%, and second episodes of mpox and cases of breakthrough infections among fully vaccinated individuals have been reported. On September 4, 2023, The Lancet Infectious Disease published a Commentary that confirmed both vaccine breakthrough infections and reinfections of MSM were reported in 2022. Aniruddha Hazra and colleagues presented a global case series of eight hMPXV reinfections and 30 vaccine breakthrough infections, constituting the most extensive description of such cases to date. Their findings confirm that neither natural immunity from a previous infection nor immunity conferred by vaccination offers complete protection against hMPXV reinfection or infection. 

On July 17, 2023, The Lancet published results from a study that concluded although real-world data estimate vaccine effectiveness to be around 85%,  immunological correlates of protection are still unknown. However, JYNNEOS vaccine recipients presented robust orthopoxviral CD4+ and CD8+ T-cell responses. The journal Eurosurveillance published research on June 15, 2023, which reported of the 230 vaccinated, eight had a breakthrough infection (3.5%), while 49 of the 254 unvaccinated contacts developed an infection (19.3%) during the early stages of the current mpox outbreak (May 17 to August 15, 2022). The effectiveness of PEP, controlling for type of close contact, sex, age, HIV infection, and HIV-PrEP use, is 88.8% (95% CI: 76.0–94.7) in preventing the development of mpox in close contact with mpox cases, or equivalently, unvaccinated close contacts of mpox cases post-exposure have an 8.9 times higher risk of developing the disease than vaccinated close contacts (95% CI: 4.2–19.1). These researchers stated vaccination against the mpox virus seems to be an effective measure for up to 7 weeks after vaccination, and vaccinated contacts had a lower risk of developing the disease than unvaccinated contacts. Additionally, if they got the disease, they had fewer symptoms.

On May 18, 2023, the NEJM published a case–control study based on data from Cosmos, a nationwide Epic EHR database, to assess the effectiveness of JYNNEOS vaccination in preventing medically attended mpox disease among adults; those who received two doses among whom the estimated adjusted vaccine effectiveness was 66% (95% confidence interval [CI], 47.4 to 78.1), and those who received one dose, among whom the estimated adjusted VE was 35.8% (95% CI, 22.1 to 47.1).

The U.K. Health Security Agency (UKHSA) announced on November 22, 2022, its estimate of Mpox vaccine effectiveness for a dose of 78% 14 or more days after vaccination. The journal Nature Medicine reported on January 31, 2023, that the real-world effectiveness of a single dose of JYNNEOS in males adjusted VE was estimated at 86% (95% confidence interval, 59–95%). 

The U.S. CDC published results from a Multijurisdictional Case-Control Study — United States, August 19, 2022–March 31, 2023; the adjusted VE was 75% for one dose and 86% for two doses of JYNNEOS vaccine, indicating substantial protection against mpox, irrespective of the route of administration or immunocompromise status. Data posted by the CDC on December 8, 2022, indicated the effectiveness of one Jynneos vaccine dose was 37%, and two doses were 69%, the duration of immunity is unknown. However, no immune correlate of protection (i.e., the minimum threshold level of antibodies needed to prevent symptoms) has been established.

Mpox Breakthrough Infections 2023

The U.S. CDC issued an MMWR on June 23, 2023, and the Clinician Outreach and Communication Activity (COCA) call on May 18, 2023, confirmed that a cluster of mpox cases was reported in Chicago, Illinois. During March 18–June 12, 2023, 40 laboratory-confirmed mpox cases were identified in Chicago, including 22 (55%), five (13%), and 13 (33%), respectively, among patients who had received two doses of JYNNEOS or one dose of ACAM2000 vaccine, those who had received one vaccine dose of JYNNEOS vaccine, and those who had not received any vaccines for mpox. The Colorado Department of Public Health and Environment reported on June 12, 2023, that three mpox cases were confirmed in Denver, and 2 cases involved people who were fully vaccinated with two doses of the Jynneos vaccine.

Public Health France published an update on March 23, 2023, confirming multiple cases of Mpox in previously vaccinated men in the Centre-Val de Loire region. The Lancet published on March 24, 2023, a clinical episode of a second virus infection in a vaccinated man. In a small study based in Chicago, IL, published by The JAMA Network on September 30, 2022, most post-vaccination Mpox infections occurred at least two breakthrough infections were observed in individuals at least three weeks after a second dose. On December 1, 2022, Eurosurveillance published a Rapid Communication detailing five post-vaccine mpox breakthrough cases on January 3, 2023. BMJ Journal published results from a study that found (0.15%) of vaccinated people developed Mpox subsequently. A non-peer-reviewed study based in France reported on August 4, 2022, that among the 276 vaccinated individuals, 12 (4%) had a confirmed Mpox breakthrough infection with no severe infection. Ten out of 12 patients developed a Mpox infection in the five days following vaccination, and two had a breakthrough infection at 22 and 25 days.


Scientists at the National Institute of Allergy and Infectious Diseases (NIAID), part of the National Institutes of Health (NIH), recently described the clinical and immunological features of a woman living with HIV who acquired mpox while participating in a long-term NIAID study at the NIH Clinical Center. In the reported case, the study participant presented with lesions consistent with mpox in August 2022, and laboratory results confirmed mpox infection. Her HIV viral load was suppressed on antiretroviral therapy, and she experienced a mild mpox case with lesions on her face, wrist, and forearm. She did not receive any mpox treatment due to her mild case. Despite these minor symptoms, laboratory results showed the study participant experienced dramatic changes in several types of immune cells, suggesting her body mounted a robust immune response to mpox infection: data showed increased levels of B cells (associated with antibody production) and changes in some types of T cells (which trigger other immune functions and destroy viruses). Of interest, laboratory findings showed no significant difference in the size of the participant's HIV reservoirs, which suggests that mpox infection did not affect the clinical HIV status of this participant. The study authors indicate more research is needed to understand the impact of mpox on people living with HIV.

On August 5, 2022, the early release of the Morbidity and Mortality Weekly Report - Interim Guidance for Prevention and Treatment of mpox in people with HIV Infection — United States, August 2022. Prompt diagnosis, treatment, and enhanced prevention efforts might reduce the risk of severe outcomes. The JYNNEOS vaccine can be safely given to people who are living with HIV infection and those who are taking preexposure prophylaxis (PrEP), says the UK NHS.

JYNNEOS Myocarditis Risk

According to the U.S. CDC, myocarditis and pericarditis have occurred following either primary vaccination or revaccination with live vaccinia virus smallpox vaccines and is a known health risk for military forces (2003). The CDC reported on October 25, 2023, that VAERS and VSD data do not suggest an increased risk for myocarditis or pericarditis following JYNNEOS. Still, the possibility of a small risk, similar to smallpox vaccines, cannot be excluded.

Since 2002, approximately 2 million U.S. armed service members have been vaccinated against smallpox. The incidence of confirmed myocarditis secondary to smallpox vaccination is estimated to be 16.1 per 100,000 service members. A recent Department of Defense study (2009) estimates 12 per 100,000 in a review of 730,000 service members. In addition, vaccine-associated myocarditis should be on the differential for patients who exhibit cardiopulmonary symptoms after recent vaccinations (2018). The FDA disclosed up to 2.1% of recipients had a cardiac event of particular interest, compared to 0.2% of placebo subjects.

JYNNEOS COVID-19 Vaccination

As of 2023, the CDC says there is limited clinical trial data on administering the Jynneos vaccine simultaneously with other vaccines. However, there are additional considerations if administering a COVID-19 vaccine. (Interim Clinical Considerations for the Use of COVID-19 Vaccines). People, particularly young adult males, might consider waiting four weeks after JYNNEOS or ACAM2000 vaccination before receiving a specific COVID-19 vaccine because of the observed risk for myocarditis and/or pericarditis after receipt of ACAM2000 and mRNA (i.e., Moderna and Pfizer-BioNTech) vaccines and the unknown risk for myocarditis and/or pericarditis after Jynneos vaccination.


The MVA-BN® vaccine is marketed under the brand names IMVANEX in the European Union and IMVAMUNE in Canada. On July 25, 2022, the European Commission (E.C.) extended Imvanex's marketing authorization to include mpox. Canada extended its contracts with Bavarian Nordic on September 20, 2022, securing IMVAMUNE® deliveries in 2023 with the option to procure additional doses annually until 2032. 


The approval of JYNNEOS for smallpox by the U.S. FDA in 2019 was based on a comprehensive development program comprising a total of 7,871 individuals aged 18 through 80 years who received at least one dose (7,109 smallpox vaccine-naïve and 762 smallpox vaccine-experienced individuals) in 22 clinical trials, including two Phase 3 studies, the latter of which showed non-inferiority in terms of immunogenicity measured by plaque reduction neutralization test of JYNNEOS compared to ACAM2000. In addition, the approval for mpox use is based on survival data obtained in lethal monkeypox virus challenge studies (FDA's Animal Rule) in non-human primates. Overall survival in various models ranged from 80% to 100% of JYNNEOS-vaccinated animals compared to 0-40% in control animals.

The U.S. FDA's emergency use authorization (EUA) for Jynneos for monkeypox was issued by Peter Marks, MD, Ph.D., in EUA Application Number 28801 on August 9, 2022. The U.S. government believes up to five Jynneos doses could be available for intradermal vaccination per vial. However, on September 28, 2022, the CDC reported most Jynneos vaccinations had been administered as post-exposure prophylaxis, and unvaccinated people had 14 times the risk of monkey.


In the U.S., the standard U.S. FDA regimen for Jynneos involves a subcutaneous (subcutaneous) route of administration with an injection volume of 0.5mL. Since August 9, 2022, the standard regimen has been authorized for people aged <18 years under an FDA-issued EUA. In the national Public Health Emergency context, the FDA authorized an alternative regimen that may be used for adults aged ≥18 under an EUA beginning August 9, 2022. The U.S. FDA confirmed on August 9, 2022, that the second vaccine dose of Jynneos should be given 28 days after the first dose. New York City began offering people second doses of Jynneos in September 2022. Oregon Health Authority figures show that, as of Oct. 17, 4,332  people had completed the two-dose series. The U.K. Health Security Agency announced on September 23, 2022, that second doses of the Jynneos vaccine would be offered to people at the highest risk from monkeypox.

JYNNEOS Post-Exposure Vaccination

The WHO's SAGE confirmed on October 10, 2022, that post-exposure vaccination (PEPV) is recommended for close contact with MPX cases, ideally within four days of first exposure and up to 14 days without symptoms. The Lancet Infectious Disease published a study on November 7, 2022, that showed the immunological signature of monkeypox virus infection, characterized by an early expansion of activated effector CD4+ and CD8+ T cells that persisted over time. In addition, almost all patients, regardless of HIV infection, developed a poxvirus-specific Th1 cell response. These results might have implications on the expected immunogenicity of monkeypox vaccination, suggesting that it might not be necessary to vaccinate people who have already been infected. Reports from the 2003 monkeypox outbreak in the midwestern USA indicate that T-cell responses last at least one year following infection. 

JYNNEOS (MVA) Fractional Formulation Study

The U.S. CDC reported on July 28, 2023, that California residents who received their first dose of mpox vaccine by intradermal or subcutaneous administration had comparable 2-dose series completion rates (60.2% and 58.8%, respectively). Similar series completion rates by route of administration were observed across all race and ethnicity groups. The NEJM published a Correspondence regarding a reanalysis of these trial results using the contemporaneous FDA Toxicity Grading Scale on April 14, 2023, that showed that the intradermal route was safe and did not lead to unacceptable local reactions. Although there was a higher incidence of moderate or severe erythema after the second vaccine dose than after the first dose, the median duration of erythema was shorter by one day in the intradermal-administration group than in the subcutaneous-administration group.

An alternative vaccination dosage study was published on September 22, 2015, in the journal Vaccine / Science Direct (Frey SE et al., Vaccine, 2015; 33(39):5225-5234) - Comparison of lyophilized versus liquid MVA (Jynneos) formulations and subcutaneous versus intradermal routes of administration in 524 healthy vaccinia-naïve subjects who were randomized to receive either a full dose of Lyophilized-SC, a full dose of Liquid-SC or 20% (2 × 107 TCID50 in 0.1 mL) of a full dose Liquid-ID MVA on Days 0 and 28. At 180 days after the second vaccination, geometric mean neutralization titers declined to 11.7, 10.2, and 10.4, with only 54.3%, 39.2%, and 35.2% of subjects remaining seropositive for the Lyophilized-SC, Liquid-SC, and Liquid-ID groups, respectively. Both the Lyophilized-SC and Liquid-ID groups were considered non-inferior (primary objective) to the Liquid-SC group.


The U.S. CDC vaccine committee stated, 'Regarding booster doses, a systematic review identified one randomized controlled trial and 17 observational studies that included 6,417 subjects. After considering geometric mean titer and seroconversion rate together, the Vaccine Work Group estimated with very low (level 4) certainty that a slight increase in disease prevention occurs after the JYNNEOS booster versus the JYNNEOS 2-dose primary series only. Therefore, the ACIP unanimously recommended JYNNEOS boosters as an alternative to ACAM2000 boosters in persons who received ACAM2000 as the primary vaccine.


JYNNEOS (MVA-BN) Vaccine (IMVANEX, IMVAMUNE) utilizes Chicken Embryo Fibroblast cells to produce the vaccine. Replication-competent poxvirus strains can cause clinical infection in humans and have an infectious virus that can be transmitted to others. However, replication-deficient poxvirus strains, including modified vaccinia Ankara (MVA), do not produce contagious viruses in humans and therefore do not cause clinical infection. As such, replication-deficient poxvirus strains pose a substantially lower risk of adverse events than replication-competent strains. 

JYNNEOS For Children

A peer-reviewed study funded by the U.K. Health Security Agency, published on June 15, 2023, concluded a single dose of MVA–B.N. for post-exposure prophylaxis was well-tolerated in children and induced robust antibody and cellular immune responses up to 15 weeks after vaccination. More extensive studies are needed to fully assess the safety, immunogenicity, and effectiveness of the MVA–B.N. vaccine in children. On September 15, 2022, the U.S. CDC confirmed that children and adolescents exposed to people with suspected or confirmed mpox infections might be eligible for post-exposure prophylaxis with vaccination. In addition, the CDC published interim Clinical guidance for Healthcare Providers in September 2022.


As of October 27, 2022, the CDC confirmed no clinical efficacy data regarding pregnant or breastfeeding women. However, the CDC stated on September 1, 2022, that pre- or post-exposure prophylaxis could be offered to pregnant or breastfeeding women. When pre- or post-exposure prevention by vaccination is chosen, JYNNEOS, a live, non-replicating viral vaccine, can be used. The virus in the vaccine does not grow and multiply in the human body, so it should not spread to an unborn child, says the UK NHS. However, if a pregnant woman contracts monkeypox, she may pass the virus to the baby.

JYNNEOS U.S. CDC Presentations

Pablo Sanchez, MD, led the U.S. CDC's ACIP Monkeypox Vaccine presentation on October 20, 2022, and February 22, 2023.

JYNNEOS Side Effects

A Research Letter on May 5, 2023, reviewed a phase 4 clinical study of adverse events following Jynneos vaccination and found that local adverse event rates were highest following intradermal administration. The adverse event rate was highest following dose 1 of intradermal vaccination (53%) and lowest following dose 2 of subcutaneous vaccination (31%). The most common adverse events were local redness, itching, and swelling following intradermal vaccination and local pain, swelling, and redness following subcutaneous vaccination.

Jonathan Duffy, MD, MPH, Immunization Safety Office, CDC Advisory Committee on Immunization Practices, presented JYNNEOS Vaccine Safety Monitoring During the 2022 Mpox Outbreak on February 22, 2023. According to VAERS, the number of serious adverse events reported after JYNNEOS was 26. The CDC reported on December 8, 2022, that the vaccine safety profile was consistent with prelicensure studies. The most common adverse health events reported were nonserious, including injection site reactions. Serious adverse events were rare among adults.

Severe adverse reactions known for replicating vaccinia virus strains, such as myocarditis, encephalitis, generalized vaccinia, or eczema vaccinatum, were not observed during Jynneos's clinical development program. The U.S. FDA reports in smallpox vaccine-naïve healthy adults, the most common (> 10%) solicited injection site reactions were pain (84.9%), redness (60.8%), swelling (51.6%), induration (45.4%), and itching (43.1%); the most common solicited systemic adverse reactions were muscle pain (42.8%), headache (34.8%), fatigue (30.4%), nausea (17.3%) and chills (10.4%).

JYNNEOS Contraindication

According to the CDC, JYNNEOS is contraindicated in persons with serious allergies to any vaccine component.


Bavarian Nordic A/S received approvals from the U.S. and E.U. regulatory authorities on July 27, 2022, to manufacture JYNNEOS®/IMVANEX® smallpox and mpox vaccine at the Company's fill and finish facility in Denmark. In addition, on August 18, 2022, Bavarian Nordic announced that the Company had agreed with Grand River Aseptic Manufacturing to fill and finish 2.5 million JYNNEOS vaccines/vials.


The AMA-issued CPT code (90611) describes the FDA-approved JYNNEOS vaccine manufactured by Bavarian Nordic to prevent smallpox and monkeypox disease in adults 18 years of age and older at high risk for smallpox or monkeypox infection.

JYNNEOS Vaccine Price

The Jynneos vaccine has not been sold commercially in the U.S. as of 2023.

JYNNEOS MVA-BN® Vaccine News 2023

September 13, 2023 - Bavarian Nordic A/S announced that it had been awarded another contract valued at more than EUR 11 million to supply its MVA-BN® smallpox vaccine to rescEU, a strategic reserve within the E.U.

July 28, 2023 - Demographic Disparities in Mpox Vaccination Series Completion, by Route of Vaccine Administration — California.

April 25, 2023 - CNBC reported Bavarian Nordic CEO Paul Chaplin confirmed, "We're looking at ways we can dramatically change the way we manufacture to increase our scale."

March 31, 2023: The U.S. CDC reported that during the current multinational outbreak, U.S. 1- and 2-dose vaccination coverage among at-risk persons reached an estimated 37% and 23%, respectively.

February 22, 2023 - The U.S. CDC presented: Epidemiology of Mpox during the Current Outbreak.

JYNNEOS Smallpox Vaccine Clinical Trial

A phase 2 study results posted as a preprint on September 9, 2022, concluded priming with either 1 or 2 doses of MVA-BN induced a durable immune memory, similar to that of older generation replicating smallpox vaccines. When the MVA-BN vaccine was administered as a booster to individuals either primed two years earlier with MVA-BN or an older generation replicating smallpox vaccine in the distant past, it elicited a similarly rapid and durable immune response that was generally safe and well-tolerated. One-dose priming with MVA induced a long-term B-cell memory that resulted in robust anamnestic responses following an MVA booster two years later, suggesting that a single dose may offer protection against future exposure.

The National Institute of Allergy and Infectious Diseases (NIAID) Tweeted on August 22, 2022, that it was launching a clinical trial for Jynneos in September 2022. 

The FDA approval of JYNNEOS for smallpox comes from a development program comprising 22 clinical trials, including two phase III trials. The program enrolled 7,871 individuals aged between 18 and 80 years who received at least one dose of the vaccine. Approval for monkeypox indication comes from survival data from studies conducted in non-human primates. The survival rate ranged from 80%-100% in animals vaccinated with JYNNEOS compared to 0%-40% in the control group.

Upon successful completion of the current study, expected in 2021, the Company plans to submit a supplement to the BLA to extend the approval for both formulations of MVA-BN, anticipated in 2022.

Clinical Trials

No clinical trials found