A groundbreaking international study, led by Queen Mary University of London, has shed light on the efficacy of the Mpox vaccine (formerly known as monkeypox). This research underscores the vital role and effectiveness of vaccination in mitigating the severity of infections.
Published in The Lancet Infectious Diseases and conducted by the SHARE-net collaborative, the study focused on 38 Mpox infections among 37 gay and bisexual men. Out of these cases, eight were reinfections, while 30 occurred after a complete vaccination regimen. Among those who had received the vaccine, the findings indicated a reduction in the number of lesions, decreased mucosal disease, and a diminished need for pain relief or hospitalization.
Severity of symptoms was evaluated using the Mpox-SSS score, developed during the 2022 multi-country outbreak. This numerical scoring system takes into account various factors, such as the lesion count, level of care required, pain medication necessity, extent of mucosal involvement, and the presence of additional bacterial infections.
The scoring system allowed for the quantification of severity. In reinfection cases, the disease exhibited milder symptoms with reduced pain medication requirements compared to the initial episode. Moreover, fewer body areas were affected, and recovery was notably faster. The first infection lasted a median of 21 days, while the second infection had a median duration of 15 days.
This study stands as the largest case series to investigate both reinfections and infections post-complete vaccination with Modified Vaccinia Ankara-Bavarian Nordic (MVA-BN).
Since May 2022, over 87,000 cases of human Mpox have been reported in 112 countries, predominantly affecting sexually active gay and bisexual men through skin-to-skin and bodily fluid contact. As indicated by previous SHARE-net global case series published in The NEJM and The Lancet, symptoms often include rashes, fevers, and blisters, with potential complications like brain inflammation and seizures. In individuals with advanced HIV disease, the mortality rate in the most immunosuppressed group can reach up to 27%.
It’s important to note that neither natural immunity from a previous Mpox infection nor post-vaccination immunity can prevent infection. However, the study reveals that both forms of immunity significantly reduce the severity of the disease.
Chloe Orkin, the lead author of the research and Professor of HIV Medicine at Queen Mary University of London, as well as the Director of the SHARE collaborative, commented, “This is encouraging news, demonstrating that post-vaccination infections are less severe, and the need for hospitalization is reduced.
“This provides clear evidence of the importance of vaccination in minimizing morbidity and controlling further outbreaks. Global access to vaccinations and treatments is crucial to containing this worldwide outbreak, particularly in regions of Africa that have historically been the hardest hit and still lack access to Mpox vaccines or treatments.”
Source: Queen Mary University of London