Mpox Outbreak: Can Smallpox Vaccine Control Spread of The Deadly Virus?

Last week, the World Health Organization (WHO) declared Mpox a public health emergency of international concern (PHEIC). The classification came as a more dangerous strain of the Mpox virus, Clade 1b, was reported outside Africa, where it has already killed 517 people. As the threat from the virus exacerbates, experts are now looking at smallpox vaccine to battle the infection.

Mpox, closely linked to the smallpox virus, has genetic similarities that allow the smallpox vaccine to provide some level of cross-protection against it. Dr Rajeev Jayadevan, an infectious diseases expert and member of the Indian Medical Association (IMA), Kochi, explains, "There is no vaccine specifically created for the Mpox virus. When the global Mpox outbreak occurred in 2022, we hoped that the smallpox vaccine could offer cross-protection."

The smallpox vaccine, based on the vaccinia virus, has shown effectiveness against Mpox due to the shared genetic characteristics between the two viruses. Data from Western nations since the 2022 outbreak indicates that people who received the modern smallpox vaccine (Jynneos) saw a substantial reduction in Mpox cases.

However, immunity from older smallpox vaccinations, administered before the disease was eradicated in the 1970s, appears less reliable. Dr Jayadevan notes that individuals vaccinated decades ago may have some residual protection, but the immunity likely wanes over time. Reports of people infected with Mpox despite prior smallpox vaccination suggest that cross-protection diminishes as years pass.

It’s important to clarify that the chickenpox vaccine, which targets the varicella-zoster virus, does not offer any protection against Mpox. As Dr Giridhar Babu, an epidemiologist and global health expert, points out, “The varicella-zoster virus belongs to a completely different family of viruses (Herpesviridae) and is unrelated to orthopoxviruses like Mpox."

The declaration of Mpox as a PHEIC highlights the urgency of addressing the outbreak. Here are the symptoms you can look for if you suspect being infected with Mpox:

Mpox symptoms are similar to those of smallpox and can include fever, muscle aches, headache, and a rash that often starts on the face and spreads to other parts of the body. The rash progresses through various stages, from flat spots to raised bumps, eventually forming scabs. This symptom profile makes early detection and diagnosis crucial.

- Fever

- Headaches

- Muscle aches

- Swollen lymph nodes

- Rash starting on the face and spreading to other parts of the body

- Rash evolving from spots to pustules, which eventually scab over

Early recognition of these symptoms is crucial for timely medical intervention and isolation to prevent the spread of the disease.