It ain't what you do, it's the way that you do it: The pitfalls of using routine data to measure early infant HIV diagnosis in HIV-exposed infants.

The four methods, applied to a range of routine data sources, resulted in estimates varying considerably, and the true coverage of EID remains unclear. Our findings highlight the importance of developing unique patient identifiers, improving training of healthcare providers using reporting systems, and ensuring the accuracy of healthcare records, to ensure the best possible health outcomes for HIV-exposed infants.