The World Health Organization has declared the recent mpox (monkeypox) outbreak a public
health emergency of international concern, as the virus has spread beyond Africa. Although
smallpox and mpox share genetic similarities, the smallpox vaccine offers only partial
protection against mpox, not complete immunity.
The recent mpox strain, known as Clade 1b, emerged in 2022 and differs from the previous
strain. Smallpox was eradicated in the US in 1972 and in India in 1979, but since then, mpox
has become more common in unvaccinated populations.
Dr. Rajeev Jayadevan, an infectious disease expert, explained that while no vaccine
specifically targets mpox, the smallpox vaccine, which is based on the vaccinia virus,
provides some cross-protection. However, immunity from childhood smallpox vaccinations,
which ceased over 45 years ago, may have diminished over time. Despite this, data from
countries affected by the 2022 outbreak indicates that the modern smallpox vaccine (Jynneos)
significantly reduced mpox cases.
Dr. Giridhar Babu, an epidemiologist, noted that while the smallpox vaccine offers some
protection due to the close relationship between the viruses, the chickenpox vaccine does not
provide any cross-protection against mpox, as chickenpox is caused by a different virus
family. He emphasized the importance of vigilance and preparedness, especially as new
variants spread and communities return to normal activities.
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