Smallpox Vaccine Candidate Found Very Effective

A Denmark based vaccine company announced the results from the pivotal Phase 3 efficacy trial of its smallpox vaccine, Jynneos™ (MVA-BN®), which has been peer-reviewed and published in The New England Journal of Medicine (NEJM).

This clinical study compared indicators of efficacy for Bavarian Nordic’s non-replicating smallpox vaccine, Jynneos (MVA-BN) to ACAM2000®, the U.S. licensed, replicating smallpox vaccine, successfully achieved both co-primary endpoints, while also demonstrating an improved safety profile versus ACAM2000. 

The study results published on November 14, 2019, demonstrated that peak neutralizing antibodies induced by Jynneos (MVA-BN) were statistically higher (almost 2-fold higher on average) than those stimulated by ACAM2000 and that primary vaccination with MVA-BN resulted in a highly attenuated take (reduction in lesion size), and in fact prevented the vaccine take in the majority of subjects re-vaccinated with ACAM2000.

Importantly, a single dose of MVA-BN induced neutralizing antibody titers comparable with ACAM2000 on Day 14, indicating the potential for use of the vaccine to protect the general population.

"Inoculation with live vaccinia virus causes a productive local infection leading to amplification of the virus, which in turn generates an immune response that clears the virus and elicits cross-protective immunity to other orthopoxviruses, including variola," explained Lindsey Baden, M.D., and Inger Damon, M.D., Ph.D, both of the Centers for Disease Control and Prevention (CDC).

This is important news since on average if a person is infected with smallpox and they are in close contact with others, the virus can spread quickly. Moreover, 3 out of every 10 people who get smallpox die.

Arguably the best biomarker in the world for vaccine efficacy is the “take.”

The take, the reaction observed after an inoculation of smallpox vaccine, is typically a small pustular lesion that occurs approximately 1 week after inoculation and often leaves a poxlike scar at the vaccination site. This reaction allows health care personnel to know that a person is immune to variola and that the immunity is long-lasting, said these researchers in a related editorial.

The most common (>10%) adverse reactions associated with Jynneos were injection site reactions (pain, redness, swelling, induration, itching) and systemic adverse reactions such as muscle pain, headache, fatigue, nausea, myalgia, and chills. 

Serious adverse reactions were reported in 0.05% of subjects who received Jynneos and included Crohn’s disease, sarcoidosis, extraocular muscle paresis, and throat tightness. 

Cardiac adverse reactions of special interest were reported in 0.08% of subjects who received Jynneos and included tachycardia, electrocardiogram T wave inversion, electrocardiogram abnormal, electrocardiogram ST-segment elevation, electrocardiogram T wave abnormal, and palpitations.

“We are very proud that our research has been acknowledged by The New England Journal of Medicine. The fact that the study results have been published by such an esteemed journal underpins the importance of the data to the medical community,” said Paul Chaplin, President, and CEO of Bavarian Nordic, in a related press release.

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Smallpox, caused by the variola virus, was a highly contagious infectious disease that caused infected individuals to develop a fever and a progressive, disfiguring skin rash. And, those who survived were usually left with scars, which were sometimes severe, says the Centers for Disease Control and Prevention.

The paper titled “Phase 3 Efficacy Trial of Modified Vaccinia Ankara as a Vaccine against Smallpox” was co-authored by Phillip R Pittman, MD, MPH, United States Army Medical Research Institute of Infectious Diseases (USAMRIID) who also led the Phase 3 trial in collaboration with the U.S. Defense Health Agency (DHA). 

The paper is available here.

The Jynneos vaccine is indicated for the prevention of smallpox and monkeypox disease in adults 18 years of age and older. and is also part of the Strategic National Stockpile, the nation’s largest supply of potentially life-saving pharmaceuticals and medical supplies for use in a public health emergency.

The Bavarian Nordic Phase 3 trial was the final clinical study to support the registration of the smallpox vaccine candidate, which was approved in September 2019 by the U.S. Food and Drug Administration.  The Phase 3 study comparing the safety and immunogenicity of MVA-BN to ACAM2000 has been partly funded with Federal funds from the Office of the Assistant Secretary for Preparedness and Response, Biomedical Advanced Research and Development Authority, under Contract No. HHSO100200700034C.

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Bavarian Nordic is a fully integrated biotechnology company focused on the development of innovative therapies against infectious diseases and cancer.

Small Pox Vaccine news published by Precision Vaccinations.