Table 1 Baseline parameter values used in mathematical model.

Parameter	Value	Source
Behavioural parameters
Preferred number of concurrent partners	1 or 2
Proportion wanting 2 partners (<35 years old)	0.05	Assumption based on Kretzschmar model12
Initial proportion of 16 year olds desiring short partnerships		Fitted to Natsal 200014,18
Men	0.6
Women	0.5
Proportion who switch from desiring short to long partnerships per year		Fitted to Natsal 200014,18
Men	0.04
Women	0.08
Mean duration of short partnerships (in days)	14	Assumption
Mean duration of long partnerships for 16 year olds (in days)	900	Fitted to Natsal 200014,18
Increase in duration (in days) per year	200	Fitted to Natsal 200014,18
Mean gap between partnerships (in days), (dispersion)*	14 (2)	Assumption
Number of sex acts per day		Assumption based on Kretzschmar model12
Short partnerships	1
Long partnerships	0.25
Infection parameters
Transmission probability per sex act	0.0375	Fitted to Natsal 200017 and Adams et al4
Duration, no treatment seeking (in days)	180	Assumption
Duration, treatment seeking (in days)	30	Assumption
Proportion seeking treatment		Fitted to Natsal 200017 and Adams et al4
Men	0.0
Women	0.045
Mean refractory period following treatment (in days), (dispersion)*	7 (10)	Assumption based on CEG guidelines21
Healthcare parameters (baseline)
Annual attendance rate at health care setting (proportion who report attending a healthcare setting in the last 12 months)	0.85	Chlamydia Recall Study20
Probability of accepting screen	0.5	Assumption based on screening studies19,22
Proportion of partners notified	0.2	Fitted to Natsal 200017 and Adams et al4
Treatment efficacy (in those partner notified or screened)	0.95	Treatment guidelines23
Mean delay (in days) before partner treatment (dispersion)*	7 (10)	Assumption based on Recall Study (unpublished)

Adapted from Turner et al.¹⁴

*Parameters drawn from a negative binomial distribution, mean, and dispersion.