Is There a Vaccine for Monkeypox?

The resurgence of monkeypox in various regions has sparked global concern, leading to increased awareness and inquiries about prevention strategies, particularly vaccination. Monkeypox, a viral zoonotic disease, is similar to smallpox but generally less severe. As the disease reemerges in new territories, the question on many minds is: Is there a vaccine for monkeypox? This article delves into the current state of monkeypox vaccination, exploring available vaccines, their effectiveness, and the broader implications for public health.

Understanding Monkeypox

Monkeypox is caused by the monkeypox virus, a member of the Orthopoxvirus genus in the Poxviridae family. The disease was first identified in 1958 when outbreaks occurred in monkeys kept for research, hence the name « monkeypox. » The first human case was recorded in 1970 in the Democratic Republic of Congo. Since then, monkeypox has primarily been reported in Central and West African countries, particularly in rural regions with close proximity to tropical rainforests.

Monkeypox symptoms resemble those of smallpox, although they are typically milder. The disease starts with fever, headache, muscle aches, and exhaustion. Within a few days, a rash develops, progressing from macules to pustules before eventually scabbing over. The illness usually lasts between two to four weeks, and while most individuals recover, severe cases can occur, particularly in children and those with weakened immune systems.

The History of Monkeypox Vaccines

The quest for a monkeypox vaccine is closely tied to the history of smallpox vaccination. The smallpox vaccine, developed using the vaccinia virus (a virus similar to monkeypox), was instrumental in eradicating smallpox globally by 1980. This vaccine also provided cross-protection against other orthopoxviruses, including monkeypox.

After the eradication of smallpox, routine smallpox vaccination was discontinued, leading to a gradual decrease in immunity to orthopoxviruses in the general population. This decline in immunity is believed to be a contributing factor to the resurgence of monkeypox cases, as individuals under the age of 40–50 are unlikely to have been vaccinated against smallpox and are thus more susceptible to monkeypox infection.

Current Vaccines Available for Monkeypox

There are two main vaccines currently available that offer protection against monkeypox:

1. ACAM2000: This vaccine is a second-generation smallpox vaccine approved for use in the United States. ACAM2000 is a live, replication-competent vaccine, meaning it contains a live virus that can replicate in the body. While it is effective against monkeypox, it is associated with a higher risk of side effects, particularly in immunocompromised individuals, pregnant women, and those with certain skin conditions.
2. Jynneos (Imvamune/Imvanex): Jynneos is a newer, third-generation smallpox vaccine that was specifically developed to have a better safety profile than older vaccines. It is a non-replicating vaccine, meaning it uses a modified form of the vaccinia virus that cannot replicate in the body, making it safer for a broader range of individuals, including those with weakened immune systems. In 2019, Jynneos was approved by the U.S. Food and Drug Administration (FDA) for the prevention of both smallpox and monkeypox.

Vaccine Effectiveness

The effectiveness of these vaccines against monkeypox is supported by historical data and recent studies. The smallpox vaccine, which shares similarities with ACAM2000 and Jynneos, has been shown to be about 85% effective in preventing monkeypox. This high level of protection is attributed to the close genetic relationship between the smallpox and monkeypox viruses.

Jynneos, in particular, has undergone clinical trials demonstrating its safety and efficacy. These studies have shown that Jynneos induces a robust immune response, with antibody levels that are believed to provide significant protection against monkeypox. Given its improved safety profile, Jynneos is now the preferred vaccine for monkeypox, especially in populations at higher risk of adverse effects from older vaccines like ACAM2000.

Who Should Get the Monkeypox Vaccine?

The Centers for Disease Control and Prevention (CDC) and the World Health Organization (WHO) have outlined recommendations for who should receive the monkeypox vaccine. The following groups are considered at higher risk and are therefore prioritized for vaccination:

• Healthcare workers: Particularly those who may come into contact with monkeypox patients or samples.
• Laboratory personnel: Individuals working with orthopoxviruses in a laboratory setting.
• People who have been in close contact with someone infected with monkeypox: This includes household contacts, sexual partners, and anyone else who has had significant exposure to the virus.
• Individuals living in or traveling to areas with high monkeypox transmission: Especially in regions where monkeypox is endemic or during an outbreak.

For the general population, widespread vaccination against monkeypox is not currently recommended, as the risk of infection remains low for most people. However, in the event of an outbreak, vaccination strategies may be adapted to control the spread of the virus.

The Role of Vaccination in Outbreak Control

Vaccination plays a critical role in controlling monkeypox outbreaks. In the context of an outbreak, ring vaccination is often employed. This strategy involves vaccinating individuals who are most likely to be infected, including those in close contact with confirmed cases and healthcare workers. By creating a « ring » of immunity around an outbreak, the spread of the virus can be contained.

In addition to ring vaccination, pre-exposure vaccination may be considered for high-risk populations, particularly in regions where monkeypox is endemic. This proactive approach can help reduce the likelihood of outbreaks and protect vulnerable communities.

Challenges and Considerations

While vaccination is a powerful tool in the fight against monkeypox, there are challenges and considerations that must be addressed. One of the primary challenges is vaccine accessibility, particularly in low-resource settings where monkeypox is more likely to occur. Ensuring that vaccines are available and affordable in these regions is crucial for effective outbreak control.

Another consideration is public awareness and education. Misinformation and vaccine hesitancy can hinder vaccination efforts, making it essential to provide clear and accurate information about the benefits and risks of the monkeypox vaccine. Public health campaigns that emphasize the safety and effectiveness of vaccines like Jynneos can help increase uptake, particularly in at-risk populations.

Conclusion

In conclusion, there is indeed a vaccine for monkeypox, and it plays a vital role in preventing the spread of this reemerging disease. The available vaccines, ACAM2000 and Jynneos, offer effective protection against monkeypox, with Jynneos being the preferred option due to its improved safety profile. While vaccination is primarily recommended for high-risk groups, it remains a key strategy in outbreak control and prevention.

As the global landscape of infectious diseases continues to evolve, the importance of vaccines in safeguarding public health cannot be overstated. Continued research, investment in vaccine distribution, and public education will be essential in the ongoing efforts to combat monkeypox and other emerging infectious diseases. By staying informed and taking proactive measures, we can help protect ourselves and our communities from the threat of monkeypox.