Prevention of Mother-to-Child Transmission of HIV-1 among Breastfeeding Mothers Using HAART: The Kisumu Breastfeeding Study, Kisumu, Kenya, 2003–2007
Timothy Thomas*1, R Masaba2, R Ndivo2, C Zeh1, C Borkowf3, M Thigpen3, K De Cock4, P Amornkul4, A Greenberg3, M Fowler3, and Kisumu Breastfeeding Study Team
1CDC Kenya, Kisumu; 2Kenya Med Res Inst, Kisumu; 3CDC, Atlanta, GA, US; and 4CDC Kenya, Kisumu
Background: Several trials are underway to assess
use of extended maternal or infant antiretrovirals (ARV) to reduce
mother-to-child transmission (MTCT) among HIV-exposed breastfed infants where
infection rates of 25 to 48% have been observed. We assessed transmission rates
in the Kisumu Breastfeeding Study (KiBS), a phase IIb single-arm prevention of
(PMTCT) trial using zidovudine/lamivudine and nevirapine (NVP) (later modified
to nelfinavir [NLF] for those women with CD4 >250 cells/µL) from 34 weeks’
gestation to 6 months’ postpartum. Infants received single-dose NVP at birth.
Women were advised to exclusively breastfeed and wean rapidly at 6 months.
Methods: We tested infant dried blood spots
collected at delivery, 2, 6, and 14 weeks and 6, 9, and 12 months using
polymerase chain reaction (PCR). Kaplan-Meier methods were used to estimate
rates of HIV infection overall, by maternal enrolment CD4 count (≤ or
>250 cells/µL) and by initial regimen (NVP or NLF) for those with maternal
CD4 >250 cells/µl.
Results: HIV infection data were available for 497
infants born alive: 27 (11 males, 16 females) became infected, 3 after 6
months. Cumulative infant HIV infection rates per 100 infants (95%CI) and by
maternal CD4 count and regimen are shown in the table. The log-rank test showed
no difference in infection rates by maternal CD4 (p = 0.89) or by
regimen (p = 0.83). The overall rate at 12 months for females was 7.4
(95%CI 4.6 to 11.9), males 4.5 (95%CI 2.5 to 8.1) (p = 0.15).
Conclusions: Low 12-month infant HIV transmission
rates were achieved using maternal HAART from late pregnancy through 6 months
of breastfeeding. There was no difference in transmission based on maternal CD4
or regimen. Further assessment—adherence to aniretrovirals, the optimal timing
for breastfeeding cessation, HIV-free survival, and drug resistance in maternal
and infant HIV isolates—is necessary to determine whether HAART is a feasible,
acceptable, safe, and efficacious strategy for PMTCT among breastfeeding women,
particularly those not meeting WHO treatment criteria.