IntroductionNigeria has a low uptake of early infant diagnosis (EID) of HIV despite its high pediatric HIV infection rate. Efforts to increase the EID of HIV have been limited by many factors. This research assessed EID uptake and challenges service providers experienced in providing routine care for HIV-exposed infants.MethodsThis is a mixed-method study at primary health centers (PHCs) in Lagos state, Nigeria. The quantitative component of the research was a review of the PMTCT Infant Follow-up Register at a purposive sample of 22 PHCs of Lagos State. The number of HIV-exposed infants (HEIs) returned for a dried blood sample (DBS) collection, date of collection, and the infant’s EID results for one year preceding the study were captured on Research Electronic Data Capture (RedCap). In-depth interviews were conducted with service providers purposively selected per participating PHC. Electronic transcripts were analyzed using MAXQDA 2020 (VERBI Software, 2019).ResultsTwenty-two Lagos State primary health centers participated in the research. Fifteen PHCs (68.2%) had PMTCT HIV counseling and Infant follow-up registers. Documentation of DBS sample collection was observed in 12 (54.6%) PHCs. Both DBS sample collection and EID results documentation were observed in only nine (40.9%) PHCs. In-depth interviews revealed both maternal and health systems’ challenges to EID. The denial of HIV status was the only maternal factor reported as a barrier against the use of EID services. Health systems challenges include unavailability of EID services, uncertainty regarding whether EID is performed in a facility, referral to secondary health facilities for EID services (leading to losses to follow-up), and delay in getting results of EID. Task-shifting of DBS collection by nurses was suggested as means to increase access to EID services.ConclusionsThere is a need to expand EID services and address women’s denial of HIV infection. Counseling women and linkage to available services are emphasized. Re-training of health workers on DBS collection and proper documentation of EID services were noted as key to improving the implementation of early infant diagnosis of HIV in the state.