Successes and failures of vertical HIV transmission prevention efforts in Canada: evidence from the Canadian Perinatal HIV Surveillance Program (CPHSP)

Background: The CPHSP collects data annually on HIV infected mothers and their infants from 22 Canadian pediatric and HIV centres across the country. The objective of this report was to describe factors associated with VT in Canada since 2004, post-implementation of routine prenatal HIV testing programs in all provinces/territories.
Methods: All children born in Canada to HIV-infected mothers from 2004-2013 in the CPHSP database were reviewed. VT rates are based on data of MIP delivered in Canada and identified within 3 months after birth; infants identified beyond 3 months of birth are tracked separately.
Results: Among 1996 MIPs, 1984 (99%) were identified antenatally or within 3 months of the child''s birth. Of these, 93% were prescribed antenatal combination antiretroviral therapy (acART), 85% >4 weeks before delivery, and 8.5% ≤4 weeks before delivery. Intrapartum intravenous zidovudine was administered to 88% of mothers and ≥4 weeks of antiretroviral prophylaxis was given to 96.4% of neonates. The VT rate for this cohort was 1.7% (33 infants); the rate was 14.6% with no acART, 6.6% with ≤4 weeks of acART before delivery and 0.12% with >4 weeks of acART before delivery. Of two VT cases that occurred despite >4 weeks of acART, one was associated with poor maternal adherence, the other with incomplete virologic suppression despite good adherence. An additional 12 infected infants were identified after 3 months of age. Eight of these 12 mothers were Canadian born (4 white, 4 Aboriginal) and 11/12 delivered in provinces with opt-out antenatal screening programs. On multivariate analysis of all 1996 MIP, receipt of no/≤4 weeks versus >4 weeks of acART was significantly associated with earlier year of birth, province/territory of birth and maternal risk acquisition category (28.4% IDU; 11.6% sex; 12.3% other) (all p< 0.01).
Conclusions: VT continues to occur in Canada despite a free universal access healthcare system. The observations that 12/45 infected infants were identified after 3 months of age and that 11/12 of those were in provinces with opt-out prenatal screening programs suggest that lack of access to routine prenatal care is a major issue contributing to ongoing VT in Canada.

A. Bitnun1, T. Lee2, L. Samson3, J. Brophy3, J. Singer2, D. Money4, A. Alimenti4, W. Vaudry5, F. Kakkar6, N. Lapointe6, L. Sauve7, for the Canadian Pediatric & Perinatal AIDS Research Group (CPARG)
1Hospital for Sick Children, Department of Paediatrics, University of Toronto, Toronto, Canada, 2CIHR Canadian HIV Clinical Trials Network, Vancouver, Canada, 3Children's Hospital of Eastern Ontario, University of Ottawa, Ottawa, Canada, 4Women's Hospital and Health Centre, University of British Columbia, Vancouver, Canada, 5Stollery Children's Hospital, University of Alberta, Edmonton, Canada, 6Hopital Ste-Justine, University of Montreal, Montreal, Canada, 7BC Women's Hospital and Health Centre & BC Children's Hospital, University of British Columbia, Vancouver, Canada