The relationship between age and sex partner counts during the mpox outbreak in the UK, 2022

• Published in: PloS one Vol. 18; no. 9; p. e0291001
• Main Authors: Brainard, Julii, Smith, Louise E, Potts, Henry W W, Rubin, G James
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 08-09-2023; Public Library of Science (PLoS)
• Subjects: Adult; Age; Algorithms; Analysis; Biology and Life Sciences; Communicable diseases; Computer and Information Sciences; Data collection; Demographic aspects; Demographics; Demography; Development and progression; Disease Outbreaks; Disease transmission; Distribution; Empirical analysis; Epidemics; Female; Females; Gays & lesbians; Gender identity; Heterosexuality; Homosexuality, Male; Human monkeypox; Humans; Infectious diseases; Influence; Male; Males; Medicine and Health Sciences; Men; Mens health; Middle Aged; Monkeypox; Mpox (monkeypox); Outbreaks; Partnerships; People and Places; Physical Sciences; Polls & surveys; Research and Analysis Methods; Sex; Sexual and Gender Minorities; Sexual orientation; Sexual Partners; Sexually transmitted diseases; Skewed distributions; Social networks; Social Sciences; STD; Subgroups; United Kingdom; United Kingdom - epidemiology; Women; Womens health; United Kingdom; United Kingdom > UK
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0291001

Understanding the dynamics of an infectious disease outbreak linked to sexual activity requires valid expectations of likely counts of unique sex partners during the infectious period. Typically, age is the key demographic trait linked to expected partner count, with many transmission models removing adults from the sexually active pool abruptly at a pre-specified age threshold. Modelling the rate of decline in partner counts with age would benefit from a better description of empirical evidence.
During the 2022 mpox epidemic in the UK, we asked individuals about their partner counts in the preceding three weeks, which is about the same as usual infectious period for persons with active mpox. We used negative binomial regression (all responses) and Weibull regression (non-zero responses) to analyse the relationship between age and partner counts, adjusted for other demographic data (such as education level and occupation), sub-dividing by three types of respondent: men who have sex with men (MSM), men who have sex with women, and women who have sex with men.
Most respondents had zero or one recent partner, all distributions were skewed. There was a relatively linear declining relationship between age and partner counts for heterosexual partnership groups, but a peak in partner counts and concurrency for MSMs in middle age years (age 35-54), especially for MSM who seemed to be in a highly sexually active subgroup.
Useful data were collected that can be used to describe sex partner counts during the British mpox epidemic and that show distinctive partner count relationships with age, dependent on partnership type.