Table 1.

Characteristics of included studies

Author (publication year)	Time period	Serodsicordant couples	Person-years of follow-up	Number of transmissions	Transmission risk depends on VL/PI	Transmission rate r(x) as a function of x=log₁₀(VL)	Duration of primary infection (days)	Transmission rate ratio between primary and asymptomatic infection
European Study Group on Heterosexual Transmission of HIV
Leynaert (1998)	1987-1992	499	NA	94	PI		90	3.15
Medical Research Council Programme on AIDS in Uganda
Carpenter (1999)	1989-1999	29	85	6	PI		365	2.4
Tanzania cohort study
Hugonnet (2002)	1991-1995	61	122	9	PI		365	2.4
Partners in Prevention HSV/HIV Transmission Study Team
Baeten (2010)	2004-2008	1096	1685	64	VL	step function
Baeten (2011)	2004-2008	2521	3509	113	VL	step function, r(x) = c*b^x
Celum (2010)	2004-2007	3360	4868	132	VL	step function
Donnell (2010)	2004-2008	3381	4467	142	VL	step function
Hughes (2012)	2004-2008	3297	NA	86	VL	r(x) = c* b^x
Lingappa (2010)	2004-2008	3381	4756	108	VL	step function, r(x) = c* b^x
Rakai Project Study Group
Gray (2000)	1994-1998	411	752	89	VL	step function
Gray (2001)	1994-1998	174	328	38	VL	step function
Kiwanuka (2009)	1997-2002	268	812	92	VL/PI	r(x) = c* b^x	365	0.8
Quinn (2000)	1994-1998	415	760	90	VL	step function, r(x) = c* b^x
Wawer (2005)	1994-1999	235	558	68	VL/PI	step function	150	11.71
Zambia HIV Research Project
Fideli (2001)	1994-2000	317	NA	109	VL	step function, r(x) = c* b^x
Malhotra (2011)	1995-2006	567	NA	240	VL	r(x) = c* b^x
Merino (2011)	1995-2006	566	1697	240	VL	r(x) = c* b^x
Song (2011)	1995-2006	568	NA	240	VL	r(x) = c*b^x
Tang (2004)	1995-2002	292	NA	141	VL	step function
Tang (2008)	1995-2006	429	1336	205	VL	step function
No primary data
Attia (2009)						step function
Boily (2009)							90-150	9.17
Chakraborty (2001)						r(x) = −n * log(1-c*b^x)
Corey (2004)						step function
Fox (2011)						step function	150	4.98
Fraser (2007)						Hill function	180	NA
Gisselquist (2005)							not reported	NA
Hollingsworth (2008)							87	26.04
Jacquez (1994)							60	NA
Modjarrad (2008)						r(x) = c*b^x
Pilcher (2004)							54	NA
Pinkerton (2008)							49	43.68
Powers (2008)							90-150	6.59
Shiboski (1992)							not reported	NA
Shiboski (1998)							690 - 1530	NA
Wilson (2008)						r(x) = −n * log(1-c*b^x)

VL: viral load, PI: primary infection; Step function: $r (x) = Σ_{i = 1}^{n} a_{i} I_{{b_{i - 1} \leq x < b_{i}}}$ , Hill function: $r (z) = \frac{B_{m a x} z^{β_{k}}}{z^{β_{k}} + {(β_{50})}^{β_{k}}}$ ; z = 10^x.