While the researchers stress that this does not indicate a widespread hidden epidemic, they warn that such silent exposure could be bypassing Nigeria\u2019s surveillance systems.<\/p>\n
\u201cWhat we are seeing is evidence that mpox exposure doesn\u2019t always look like the textbook description,\u201d Adam Abdullahi, the study\u2019s lead author told\u00a0SciDevNet.<\/p>\n
\u201cIn some people, particularly in settings with partial population immunity, the virus may circulate quietly, leaving immune footprints that routine clinical surveillance will miss.\u201d<\/p>\n
The study comes at a critical moment for Nigeria\u2019s public health response. In 2024, the country became the first in Africa to\u00a0begin an mpox vaccine rollout<\/a>, largely guided by reported symptomatic cases.<\/p>\n But the new evidence raises questions about whether symptom-based surveillance alone is sufficient to inform vaccination strategies.<\/p>\n Mpox is a zoonotic disease caused by the\u00a0MPXV virus<\/a>, spreading through animal-to-human or close person-to-person contact. It is commonly associated with fever, swollen lymph nodes and a painful rash.<\/p>\n For decades, protection against mpox came indirectly through routine smallpox vaccination, which ended globally after smallpox was eradicated in 1980.<\/p>\n Since then, a growing proportion of the population has lacked this immunity. In Nigeria and across parts of West and Central Africa, this shift has coincided with renewed mpox transmission, including outbreaks recorded between 2022 and 2024.<\/p>\n Hidden exposure<\/p>\n To better understand how widely the virus may be circulating, the scientists analysed archived blood samples from 176 healthy Nigerian adults originally enrolled in SARS-CoV-2 vaccine studies. The samples were collected from healthcare workers in 2021 and community volunteers in 2023.<\/p>\n None of the participants had received mpox or smallpox vaccination in adulthood, and none were known to have been exposed to mpox.<\/p>\n The results showed that 14 per cent of participants had retained antibodies linked to historic smallpox vaccination, concentrated among those born before 1980\u2014the last generation to receive childhood vaccinations. This finding reflects what scientists call a generational \u201cimmunity gap\u201d.<\/p>\n However, an unexpected finding was also identified. When follow-up samples were collected from participants\u2014typically after around nine months\u2014about 3 per cent showed clear evidence of a new immune response, consistent with recent mpox exposure. These individuals had no recorded mpox diagnosis and did not report any related symptoms.<\/p>\n The researchers say this suggests mpox is spreading silently, bypassing traditional healthcare surveillance.<\/p>\n \u2018Low-level\u2019 spread<\/p>\n To contextualise these findings, the team analysed over 100 mpox genomes collected across Nigeria. The data indicates that while the virus continues to circulate, its spread is constrained by residual immunity in older populations, according to the researchers.<\/p>\n Ravindra Gupta, a senior author on the study from the Cambridge Institute of Therapeutic Immunology and Infectious Disease, said the results point to sustained low-level transmission rather than unchecked spread.<\/p>\n![\"Mpox_Factsheet](\"https:\/\/www.europesays.com\/africa\/wp-content\/uploads\/2026\/02\/1770612727_951_Mpox_AfricaCDC.jpg\")
<\/p>\n