Single Dose of MVA-BN Vaccine Provides Moderate Protection Against Mpox Infection in Ontario, Canada

Centrala begrepp

A single dose of the MVA-BN vaccine is moderately effective in preventing mpox infection, according to a real-world study in Ontario, Canada.

Sammanfattning

The study aimed to estimate the real-world effectiveness of the MVA-BN vaccine against mpox infection. Researchers analyzed data from several linked databases in Ontario, Canada, including laboratory, vaccination, reportable diseases, and health administrative data.
The study population consisted of 9,803 men aged 18 years or older who had a history of being tested for syphilis, a laboratory-confirmed bacterial sexually transmitted infection (STI) in the previous year, or had filled a prescription for HIV pre-exposure prophylaxis in the previous year. The study period was from June to November 2022, during which time 691 people in Ontario were diagnosed with mpox.
Vaccinated men who had received the first dose of MVA-BN at least 15 days earlier were matched 1:1 with unvaccinated men based on age, geographical region, past HIV diagnosis, number of bacterial STI diagnoses, and receipt of any non-MVA-BN vaccine in the previous year. During a median follow-up of 85 days for vaccinated individuals and 86 days for unvaccinated individuals, there were 21 mpox infections in the vaccinated group and 50 in the unvaccinated group.
The study found that a single dose of MVA-BN was 58% effective in preventing mpox infection. The authors noted that this moderate effectiveness, combined with other preventive measures, can have a significant impact on reducing mpox transmission. They emphasized the importance of making the vaccine widely available and accessible, especially in regions experiencing large mpox outbreaks.

Statistik

There were 691 people diagnosed with mpox in Ontario during the study period from June to November 2022.
The study population consisted of 9,803 men aged 18 years or older.
During the follow-up period, there were 21 mpox infections in the vaccinated group and 50 in the unvaccinated group.
The hazard ratio for infection in the vaccinated group compared to the unvaccinated group was 0.42, indicating a 58% vaccine effectiveness for a single dose of MVA-BN.

Citat

"Data on this vaccine's effectiveness with just a single dose are useful for mobilizing vaccine efforts and in designing and implementing a multipronged prevention strategy to prevent outbreaks or reduce the size of outbreaks when they occur."
"When the mpox outbreak expanded into Canada, vaccines were made available and rapidly rolled out. The rollout of the first dose happened quickly to try and prevent as many infections as possible. There were no randomized clinical trials at the time to measure how well the vaccine worked, hence our study."
"In combination with other measures to help prevent infection, such as awareness of developing symptoms and reducing your contact when you have an infection, [MVA-BN] can have a really large impact."

Viktiga insikter från

One Dose of MVA-BN Moderately Effective Against Mpox

by Fran Lowry på www.medscape.com 09-18-2024

https://www.medscape.com/viewarticle/one-dose-mva-bn-moderately-effective-against-mpox-2024a1000gx3

Djupare frågor

What factors influenced the decision of the at-risk population to not take the vaccine, and how could this have biased the study outcomes?

Several factors may have influenced the decision of the at-risk population to not take the MVA-BN vaccine. These factors could include:

Perceived Risk: Individuals may have underestimated their risk of contracting mpox, leading to a lack of urgency in seeking vaccination.
Access and Availability: Barriers such as transportation, availability of vaccination sites, and scheduling conflicts could have deterred individuals from getting vaccinated.
Misinformation and Stigma: Misinformation about the vaccine's safety and efficacy, as well as stigma associated with mpox, particularly among certain demographics, may have contributed to vaccine hesitancy.
Previous Vaccination History: Individuals with prior vaccinations (e.g., smallpox) might have felt less inclined to receive the new vaccine, believing they had sufficient immunity.
Cultural and Social Factors: Cultural beliefs and social norms can significantly impact health behaviors, including vaccination uptake.

These factors could introduce bias in the study outcomes by skewing the population of vaccinated individuals towards those who are more health-conscious or have better access to healthcare resources. If the unvaccinated group included individuals who were less likely to engage with healthcare systems or who had different health-seeking behaviors, the comparison between vaccinated and unvaccinated groups may not accurately reflect the true effectiveness of the vaccine. This limitation highlights the importance of understanding the social determinants of health when interpreting the results of observational studies.

How do the findings of this study compare to the effectiveness of the MVA-BN vaccine in other real-world settings or clinical trials?

The findings of this study, which reported an estimated vaccine effectiveness of approximately 58% for a single dose of MVA-BN against mpox, align with some previous studies but also highlight variability in effectiveness across different contexts.
In other real-world settings, such as the United States and Europe, studies have shown varying effectiveness rates for the MVA-BN vaccine, often influenced by factors such as population demographics, the timing of vaccination relative to outbreak peaks, and the presence of other public health measures. For instance, some studies have reported effectiveness rates ranging from 50% to 85% depending on the population and the timing of vaccination.
Clinical trials, while more controlled, may not fully capture the complexities of real-world effectiveness due to differences in population characteristics, healthcare access, and behavioral factors. The current study's use of an emulated target trial design helps mitigate some biases common in observational studies, but it still reflects the challenges of translating clinical trial results to broader public health scenarios.
Overall, while the 58% effectiveness observed in this study is promising, it underscores the need for ongoing research to better understand the vaccine's performance in diverse populations and settings, particularly as new variants of mpox may emerge.

What other public health interventions, in addition to vaccination, could be implemented to further reduce the spread of mpox in the Canadian context?

To further reduce the spread of mpox in Canada, several public health interventions can be implemented alongside vaccination efforts:

Public Awareness Campaigns: Educating the public about mpox symptoms, transmission routes, and the importance of vaccination can help increase awareness and encourage preventive behaviors.

Targeted Outreach Programs: Engaging with high-risk communities, such as gay, bisexual, and other men who have sex with men, through tailored outreach programs can improve vaccine uptake and promote safe practices.

Enhanced Testing and Surveillance: Increasing access to testing for mpox and improving surveillance systems can help identify outbreaks early and implement timely interventions.

Contact Tracing: Implementing robust contact tracing protocols can help identify and notify individuals who may have been exposed to mpox, allowing for prompt vaccination and preventive measures.

Access to Healthcare Services: Ensuring that at-risk populations have easy access to healthcare services, including vaccination and treatment for sexually transmitted infections, can help mitigate the spread of mpox.

Behavioral Interventions: Promoting safe sex practices and reducing risky behaviors through community programs can help lower transmission rates.

Collaboration with Community Organizations: Partnering with local organizations that serve at-risk populations can enhance outreach and support for vaccination efforts.

By combining vaccination with these comprehensive public health strategies, Canada can better manage and reduce the incidence of mpox, ultimately protecting vulnerable populations and the broader community.