Bavarian Nordic has reported data from the Phase III efficacy study of MVA-BN (Jynneos) vaccine, which is designed to prevent smallpox and monkeypox disease in adults aged above 18 years.

The results have been published in the New England Journal of Medicine (NEJM).

Jynneos is a suspension of live, non-replicating attenuated modified vaccinia ankara (MVA) virus designed to trigger an immune response in the body.

The Phase III trial compared the safety and immunogenicity of MVA-BN to US-licensed smallpox vaccine ACAM2000.

Bavarian Nordic said that the trial met its co-primary endpoints, with the company’s vaccine producing statistically higher peak neutralising antibodies versus ACAM2000.

Primary vaccination with MVA-BN was also associated with a highly attenuated take or decrease in lesion size. Data showed that the vaccine take was prevented in most patients re-administered with ACAM2000.

The company noted that a single dose of its vaccine triggered neutralising antibody titers comparable to that of ACAM2000 at day 14.

This data supported the registration of Jynneos, which secured US regulatory approval in September this year. The vaccine has been assessed in a comprehensive development programme of 22 clinical trials, including two Phase III trials.

Approval of Jynneos for smallpox is based on results from the development programme, while its authorisation for monkeypox is based on survival data from challenge studies in non-human primates.

The vaccine’s safety was studied in healthy adults who previously received the smallpox vaccine, as well as vaccine-naïve healthy subjects, patients with HIV infection, and adults with atopic dermatitis.

Earlier this week, the company completed the enrolment of smallpox patients in a Phase III lot-consistency trial, which is intended to support US licensure of a long-lasting, freeze-dried formulation of the vaccine.