Table 2.

Mother-to-child transmission assumptions

Parameter	Value (mean)	Standard deviation*	Source
% of pregnant HIV+ women with
CD4 >500	36.6%	-	Meta-analysis of
CD4 350-500	24.5%	-	published studies42
CD4 200-349	24.9%	-
CD4 <200	14.0%	-
Transmission rate at/before birth, from chronically-  infected women with no ARV prophylaxis, with
CD4 >500	13.4%	-	Meta-analysis of
CD4 350-500	15.2%	-	published studies42
CD4 200-349	25.8%	-
CD4 <200	35.0%	-
Transmission rate at/before birth, from acutely-  infected women with no ARV prophylaxis	35.0%	8.0%	Table 1, Rollins et al20, 21
% of HIV-diagnosed women who receive  single-dose nevirapine, if not starting ART	75.0%	10.0%	Stringer et al,43 Sherman et al,44  Nkonki et al45
% reduction in perinatal MTCT if mother  receives single-dose nevirapine	40.0%	-	Leroy et al46
% reduction in perinatal MTCT if mother  receives short-course zidovudine	65.0%	-	Sperling et al1
% reduction in perinatal MTCT if mother receives  single-dose nevirapine + short-course zidovudine	80.0%	-	Dabis et al,47 Lallemant et al48
Transmission rate at/before birth, from chronically-  infected women starting long-term ART	2.0%	-	Tonwe-Gold et al,49 Peltier et al,50  Palombi et al,51 Hoffman et al52
Probability of MTCT from chronically-  infected mothers, per year of mixed feeding	14.0%	2.5%	Meta-analysis,53 adjusted to reflect effect of excluding EBF
Probability of MTCT from acutely-  infected mothers, per month of mixed feeding	16.0%	3.0%	Derived from Table 1 using  equation 1
Ratio of postnatal transmission risk per month  of EBF to postnatal transmission risk per month  of mixed feeding	50.0%	15.0%	Coovadia et al,54 Becquet et al55
% reduction in monthly postnatal MTCT risk  if child receives extended nevirapine prophylaxis	60.0%	-	Kumwenda et al,56 Chasela et al,57  SWEN Study Team58
% reduction in monthly postnatal MTCT risk  if mother receives long-term ART	80.0%	-	Taha et al59

^*Standard deviations are shown only for those parameters that are included in the uncertainty analysis.