What is Mpox Vaccine

Mpox (formerly known as monkeypox) is a zoonotic disease caused by the monkeypox virus, closely related to the variola virus responsible for smallpox. While mpox is less severe and less transmissible than smallpox, its global spread has underscored the importance of vaccination. This article provides an in-depth exploration of available mpox vaccines, their features, safety, and recommendations for use, alongside a discussion of cutting-edge research in the field. Two main vaccines are currently available for mpox prevention: JYNNEOS and ACAM2000. Each has distinct features tailored to specific populations and scenarios.

Mpox Vaccine JYNNEOS

JYNNEOS, also referred to as Imvamune or Imvanex in some regions, is a non-replicating, live-attenuated vaccine derived from the Modified Vaccinia Ankara (MVA) strain. It is designed for use against both smallpox and mpox.

• Mechanism of Action: JYNNEOS contains a modified virus incapable of replication in the human body. This ensures a strong immune response with minimal risk of adverse effects, making it a safer choice for immunocompromised individuals.
• Administration: Administered as two doses, spaced at least 28 days apart, either subcutaneously (preferred) or intradermally in certain cases.
• Target Populations: Recommended for adults aged 18 years and older, with use in younger populations considered on a case-by-case basis in high-risk scenarios.
• Regulatory Approvals: Approved by multiple regulatory bodies globally.
• Advantages: Favorable safety profile, easy administration, and suitability for diverse populations, including those with weakened immune systems.

Mpox Vaccine ACAM2000

ACAM2000 is a replication-competent vaccine derived from a live-attenuated vaccinia virus. Initially developed for smallpox, it has been extended for use against mpox under specific protocols.

• Mechanism of Action: The vaccine replicates within the host, producing a localized reaction known as a "vaccine take," which signifies immunity development.
• Administration: Given as a single dose using a bifurcated needle, which requires specialized training for proper delivery.
• Target Populations: Typically limited to healthy adults without underlying conditions such as immunodeficiency, cardiac diseases, or active eczema.
• Regulatory Approvals: Approved by multiple regulatory bodies for use in specific high-risk populations.
• Limitations: Higher risk of adverse effects, including myocarditis and progressive vaccinia in vulnerable individuals.

Both vaccines represent vital tools in the global response to mpox, with JYNNEOS generally preferred for its enhanced safety and ease of administration.

Mpox Vaccines Availability

Global availability of mpox vaccines is constrained by limited production and high demand, particularly in outbreak regions. International collaboration has been crucial in ensuring equitable access.

• Global Stockpiles: Many nations, including the United States and European countries, have stockpiled JYNNEOS and ACAM2000 to prepare for potential outbreaks.
• Prioritization: Vaccines are prioritized for high-risk groups, including healthcare workers, laboratory personnel, close contacts of infected individuals, and populations with high exposure risk, such as men who have sex with men (MSM).
• Distribution Challenges: Limited production capacity and logistical issues in distributing vaccines to low-income and remote regions remain significant challenges.

Fig 1. Development of mpox vaccines in the future¹

Timing of Mpox Vaccination

The timing of vaccination is critical to its effectiveness,

• Pre-exposure Prophylaxis (PrEP): Recommended for individuals in high-risk professions or those traveling to outbreak areas. Vaccination should occur 4–6 weeks before potential exposure to ensure optimal protection.
• Post-exposure Prophylaxis (PEP): Vaccination within 4 days of exposure provides the highest likelihood of preventing disease onset. If administered between 4 and 14 days post-exposure, it may still reduce disease severity.
• Routine Vaccination: Not currently recommended for the general population due to the low transmission risk in non-endemic regions.

Mpox Vaccine Side Effects

Both vaccines are associated with side effects, though their profiles differ significantly.

JYNNEOS

• Common Side Effects: Injection site reactions (pain, swelling, redness), mild fatigue, headache, and muscle aches.
• Rare Reactions: Adverse events are uncommon but may include localized swelling or mild allergic reactions.
• Suitability: Safe for use in immunocompromised individuals, pregnant women (with risk-benefit analysis), and those with chronic health conditions.

ACAM2000

• Common Reactions: Formation of a pustule at the vaccination site, followed by a scab and potential scarring.
• Serious Adverse Effects:
  • Myocarditis and pericarditis, particularly in individuals with pre-existing cardiac conditions.
  • Progressive vaccinia in immunocompromised individuals.
  • Rare risk of inadvertent autoinoculation to other body sites.
• Precautions: Recipients must follow strict post-vaccination care to prevent transmission of the live virus to others.

How Long does the Mpox Vaccine Last

• JYNNEOS: Provides immunity for at least 2–3 years, with booster doses under consideration to extend protection.
• ACAM2000: Offers longer-lasting immunity but requires more frequent monitoring due to its safety concerns.

Ongoing research aims to refine booster recommendations and optimize long-term immunity.

Mpox and COVID-19 Vaccines

The concurrent administration of mpox and COVID-19 vaccines raises questions about safety and timing.

• Overlap of Side Effects: Both ACAM2000 and mRNA COVID-19 vaccines carry a rare risk of myocarditis, prompting recommendations to separate their administration by a few weeks for high-risk individuals.
• No Known Interference: Current evidence suggests no significant immunological interference between JYNNEOS and COVID-19 vaccines.

Frontiers in Mpox Vaccine Research

Mpox vaccine research is rapidly evolving, with innovative approaches being explored to enhance protection and accessibility.

• Next-Generation Vaccines: Development of subunit and mRNA-based vaccines to offer improved safety and scalability.
• Broad-Spectrum Solutions: Efforts to create vaccines targeting multiple orthopoxviruses, reducing the need for separate immunizations.
• Immunological Insights: Studies on correlates of protection to better understand immune responses and optimize vaccine formulations.
• Digital Health Integration: Leveraging AI and machine learning to predict outbreaks and model vaccine efficacy in diverse populations.
• Global Collaboration: Initiatives like CEPI (Coalition for Epidemic Preparedness Innovations) focus on equitable access and accelerated vaccine development.

Creative Biolabs actively contributes to these advancements, offering advanced vaccine-based anti-monkeypox drug discovery solutions to support cutting-edge research and ensure preparedness for future challenges. For a deeper dive into our vaccine-based solutions, please visit the following links:

• mRNA Vaccine-Based Anti-monkeypox Drug Discovery Solutions
• Virus-Like Particle Vaccine-Based Anti-monkeypox Drug Discovery Solutions
• Inactivated Virus Vaccine-Based Anti-monkeypox Drug Discovery Solutions
• DNA Vaccine-Based Anti-monkeypox Drug Discovery Solutions

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