The HIV ZIP study completed enrollment of 200 pregnant women (174 HIV infected and 26 HIV uninfected) and 195 of their offspring who resided in the United States, Puerto Rico, and Brazil. For study completion, the primary study tasks relate to supporting study monitoring activities through the last participant visit, data cleaning, and data analysis. The last maternal delivery visit for HIV ZIP occurred in June 2019, and the last participant (infant) visit occurred in September 2020. Data cleaning of the final datasets and database lock were completed on December 30, 2020. Delivery of the final dataset to the study statisticians occurred on January 20, 2021. HIV ZIP was a feasibility study of a prospective international cohort of pregnant women and their infants from those pregnancies. Its goals were to evaluate the feasibility of a comparative study of the incidence of Zika virus (ZIKV) infection among pregnant women with and without Human Immunodeficiency Virus (HIV) infection and to determine the risk of adverse outcomes associated with ZIKV/HIV co-infection across clinical sites in the continental United States (U.S.), Puerto Rico (P.R.), and Brazil. The study was designed to (1) determine the feasibility of satisfactorily achieving accrual targets, (2) confirm the adequacy of statistical assumptions for power and sample size considerations for a future large scale study in this patient population, and (3) provide adequate statistical power to detect clinical meaningful differences in the proportions of HIV-infected women with unsuppressed HIV viral load between HIV-infected women with Zika and HIV-infected women without Zika infection, assuming 10% of the HIV-infected women enrolled (and meeting Zika risk criteria) have ZIKV infection by delivery. The primary study analysis of producing a report that addresses each of the topics enumerated above could not be fulfilled because Phase I’s feasibility objective was not achieved (i.e., to enroll at least 10% of women who were co-infected with HIV and Zika). Nevertheless, the protocol team developed numerous research concepts that align with the other primary and secondary study objectives. These research concepts address HIV treatment and disease parameter comparisons between pregnant women living with HIV in Brazil and the U.S., general and ART-related developmental outcomes on infants, the impact of environmental exposures on birth outcomes among women living with HIV, cytomegalovirus shedding in HIV-infected women and infant development outcomes, and the immunogenicity of Tdap in HIV-infected pregnant women and passively acquired antibodies in their infants.