BTN News: In recent years, the global health community has shifted its focus to a previously lesser-known disease: mpox, formerly known as monkeypox. Historically confined to sporadic outbreaks in certain African regions, mpox captured worldwide attention when it began spreading rapidly to over 70 countries by May 2022, where it had never been documented before. This sudden surge in cases triggered a global effort to curb its spread, with vaccines emerging as a crucial line of defense. Two primary vaccines have been identified as effective tools in the battle against mpox: JYNNEOS and ACAM2000. Although these vaccines were originally developed to combat smallpox, they have proven instrumental in preventing mpox due to the close relation between the two viruses. Below, we explore the specifics of these vaccines, their administration, efficacy, and the role they play in mitigating this public health concern.
JYNNEOS Vaccine: The Preferred Option
JYNNEOS, also known as MVA-BN, is a modified vaccinia virus vaccine that has been attenuated, meaning the virus has been weakened to the point where it cannot replicate in the human body. Approved by the U.S. Food and Drug Administration (FDA) for the prevention of both smallpox and mpox, JYNNEOS has become the vaccine of choice in many countries, particularly the United States, during the 2022 mpox outbreak. This vaccine is administered in a series of two injections, given either intradermally or subcutaneously with a four-week interval between doses.
JYNNEOS is particularly recommended for individuals at high risk of exposure, including those who have had close contact with confirmed or suspected cases of mpox. The ease of administration and the safety profile of JYNNEOS have made it the go-to option, especially in populations where minimizing side effects is crucial. Unlike other vaccines, JYNNEOS does not require the development of a post-vaccination blister to indicate success, simplifying the vaccination process for both healthcare providers and recipients.
ACAM2000 Vaccine: A More Complex Approach
ACAM2000, another vaccinia virus vaccine, also offers protection against mpox through cross-immunity. However, this vaccine uses a live virus that is capable of replicating within the human body, which makes its administration more complex and riskier for certain individuals. Administered through a unique technique involving a series of rapid punctures with a bifurcated needle, ACAM2000 requires the development of a small blister at the injection site as a marker of successful immunization.
The use of ACAM2000 is generally limited to specific cases due to the associated risks, particularly for individuals with compromised immune systems, skin disorders, cardiovascular conditions, pregnant or breastfeeding women, and infants under one year of age. The replication of the virus in these populations could lead to serious side effects, hence the vaccine is reserved for those who have no contraindications and are at high risk of mpox exposure.
Efficacy of the Vaccines: How Well Do They Work?
The efficacy of these vaccines has been a subject of ongoing research, with the most reliable data coming from observational studies conducted in Africa, where mpox has been endemic, and from the global outbreak response in 2022.
JYNNEOS Efficacy: Historical data from Africa suggest that smallpox vaccines, including JYNNEOS, are about 85% effective in preventing mpox. However, it is important to note that prior vaccination against smallpox does not guarantee lifelong immunity. Those who have been vaccinated may still contract mpox, though the symptoms are likely to be milder. Data from the 2022 outbreak further supported the effectiveness of JYNNEOS, showing that men who had received at least one dose of the vaccine were 14 times less likely to contract mpox compared to those who were unvaccinated. Nonetheless, completing the full vaccination course with two doses remains essential for robust protection.
ACAM2000 Efficacy: Like JYNNEOS, ACAM2000 has shown significant effectiveness in preventing mpox, owing to the shared characteristics of the vaccinia and mpox viruses. However, the stronger immune response elicited by ACAM2000 also comes with higher risks, limiting its use to individuals who are at elevated risk and who do not have contraindications to the vaccine. Given its more intense response and the potential for serious side effects, ACAM2000 is used selectively, often in situations where no other vaccination option is feasible.
Conclusion: Vaccines as a Critical Tool in the Fight Against Mpox
As the world continues to grapple with the spread of mpox, the role of vaccines like JYNNEOS and ACAM2000 cannot be overstated. While JYNNEOS remains the preferred choice due to its safer profile and ease of administration, ACAM2000 serves as a critical option for those who need it and can safely receive it. The global health community’s experience during the 2022 outbreak has underscored the importance of vaccination, with data showing significant reductions in mpox incidence among those who were vaccinated. As research continues and more data becomes available, these vaccines will remain at the forefront of efforts to control and eventually eliminate mpox as a global health threat.
