Introduction

In an insightful new study published in The BMJ, researchers have unveiled compelling evidence that a single dose of the Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN) smallpox vaccine holds moderate effectiveness in preventing mpox infection.

With the World Health Organization (WHO) declaring mpox a global public health emergency for the second time in just three years this August—a worrying trend that has alerted health officials worldwide—this discovery could be pivotal in addressing the ongoing crisis.

Current Situation in Congo

Despite the promising results, the current situation in Congo remains dire. Although two mpox vaccines, namely LC16 (produced by KM Biologics) and Jynneos (produced by Bavarian Nordic), have been granted emergency use approval, the immunization infrastructure is lacking.

Only a scant 15,000 doses of Jynneos are currently available, starkly contrasting with the estimated 10 million doses needed to effectively manage the outbreak. As of August 2022, these vaccines have not yet made their way to pharmacies, underlining the urgency for greater resource allocation and distribution strategies.

Study Details

The study involved 9,803 men aged 18 and older who had a history of being tested for syphilis or who had recently been diagnosed with other bacterial sexually transmitted infections (STIs). Participants were administered a single dose of the MVA-BN vaccine, and the significant focus was on diagnosing mpox infections confirmed by polymerase chain reaction (PCR) tests.

Findings

The findings reveal that out of the total participants, 272 received an mpox diagnosis during the study period, with 15 requiring hospitalization.

After a median follow-up of 85 days for vaccinated individuals, the results showed that 21 infections occurred among those vaccinated—equating to an infection rate of 0.09 per 1,000 person-days—compared to 50 infections in the unvaccinated group (0.20 per 1,000 person-days).

Astonishingly, the hazard ratio indicates that vaccinated individuals had nearly a 58% lower risk of contracting mpox as compared to unvaccinated individuals.

Conclusions

These results illustrate not only the moderate efficacy of a single dose of the MVA-BN vaccine in preventing mpox infections—estimated at about 58%—but they also emphasize the urgent need for further vaccine distribution to vulnerable communities.

The study highlighted that no protective effect against STIs was observed, something researchers did not anticipate.

“This evidence reinforces the notion that the MVA-BN vaccine can play a crucial role in protecting communities at risk from mpox,” the authors of the study stated.

As public health officials grapple with the implications of these findings, the spotlight now falls on making this vaccine increasingly accessible in at-risk populations around the globe.

As the world continues to confront mpox, the findings of this research offer a beacon of hope and emphasize the pressing need to ramp up vaccination efforts to curb future outbreaks.