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Scientists comment on additional cases of Clade Ib Mpox being detected by the UK Health Security Agency (UKHSA).
Prof Thomas House, Professor of Mathematical Statistics, University of Manchester, said:
“During the 2022 Mpox outbreak, work showed that secondary attack rates in UK households were small, typically around 5%. While it would be mistaken (because infections are typically not independent events) to square this number to obtain the probability of seeing two household cases under the assumption that the current outbreak is equally infectious to the 2022 outbreak, a cluster involving two household infections should increase the credibility of the hypothesis that the current outbreak is more infectious in households than 2022.”
Dr Jonas Albarnaz, Institute Fellow, The Pirbright Institute, said:
“This report is relevant because these two additional cases might indicate household transmission of clade 1b mpox outside Africa for the first time. However, more details about these 3 cases are necessary to determine if transmission indeed happened in the UK.
“Since the emergence of clade 1b mpox in East DRC, countries implemented surveillance and contact-tracing strategies to detect possible importations early on, following WHO recommendations. These measures enabled the detection of imported clade 1b cases in Sweden, Thailand, India, and Germany in individuals with recent travel history. However, further transmission to close contacts has not been reported in any of these countries.
“Nonetheless, the detection of the additional cases in household contacts of the first clade 1b in the UK shows the heightened surveillance and contact-tracing measures are working.”
Prof Paul Hunter, Professor in Medicine, UEA, said:
“Not surprising that secondary household contacts have become infected. Mpox is generally not very infectious except during close and intimate contact. Spread within households between sexual partners or between parents and children has been reported. During the 2022 epidemic of clade 2b, about 1 in 20 (4%) of household contacts of a case got infected. The risk was greater (12%) in sexual household contacts but only 1.3% in non-sexual household contacts1.
“So, we can expect to see some risk of infection in household contacts and this new report is not surprising. Whether the new clade 1b is any more infectious in European settings than the previous clade 2b is uncertain.
“Nevertheless, outside of household and sexual contact the risk is still extremely low.”
https://www.gov.uk/government/news/ukhsa-detects-first-case-of-clade-ib-mpox
Declared interests
Prof Thomas House: “None”
Dr Jonas Albarnaz: “No conflict of interests to declare.”
Prof Paul Hunter: “Nothing to declare.”