Preclinical data suggest that Moderna’s mpox vaccine could be superior to other alternatives currently approved, according to new research published Wednesday.
Scientists reported in the journal Cell that non-human primates given two doses of Moderna’s mpox vaccine four weeks apart averaged 54 lesions at their peak, below the threshold for grave disease as defined by the WHO. By contrast, four out of six animals given two doses of modified vaccinia Ankara-based vaccines, the kind that Bavarian Nordic’s approved shot Jynneos is based on, had lesion counts that constituted grave disease.
No primates vaccinated with either Moderna’s candidate or the virus-based option died due to infections. Researchers concluded that the mRNA-based vaccine had “superior protection” to the virus-based vaccine “with respect to viral load, weight loss, and lesion control.”
Scientists also measured the duration of the disease, counting from lesion onset to resolution. They found that the length of the disease was shorter by more than 10 days in primates receiving Moderna’s candidate compared to the other vaccine.
The preclinical findings bode well for Moderna, which became a household name thanks to the development of its Covid-19 vaccine that rivaled Pfizer and BioNTech on the global stage. The vaccines business has become more unstable in the last year, causing Moderna to pare down its financial expectations and elevate other parts of its pipeline, namely a cancer therapy being developed in conjunction with Merck’s Keytruda.
Even before sales of its Covid vaccine began to wane, Moderna was on the fence about its mpox ambitions. In the summer of 2022, when the first global outbreak of mpox took hold, Moderna said it was testing a preclinical option. But by the beginning of 2023, CEO Stéphane Bancel said it wasn’t a top priority for the company.
Plans for human trials persisted, however, despite the global urgency dissipating. A Phase 1/2 trial of its orthopoxvirus vaccine (a family of viruses that includes mpox) ultimately launched in August 2023 and is slated to complete in June 2025. The vaccine is being tested in 351 healthy adults across the UK.
A Moderna spokesperson declined to specify when interim data could be expected, reiterating that the trial is slated to complete next year.