Objectives: The Oxford-AstraZeneca COVID-19 vaccine (ChAdOx1 nCoV-19 or Vaxzevira) builds on nearly two decades of research and development (R&D) into Chimpanzee adenovirus-vectored vaccine (ChAdOx) technology at the University of Oxford. This study aims to approximate the funding for the R&D of the ChAdOx technology and the Oxford-AstraZeneca vaccine, and assess the transparency of funding reporting mechanisms. Design: We conducted a scoping review and publication history analysis of the principal investigators to reconstruct the funding for the R&D of the ChAdOx technology. We matched award numbers with publicly-accessible grant databases. We filed Freedom Of Information (FOI) requests to the University of Oxford for the disclosure of all grants for ChAdOx R&D. Results: We identified 100 peer-reviewed articles relevant to ChAdOx technology published between 01/2002 and 10/2020, extracting 577 mentions of funding bodies from funding acknowledgement statements. Government funders from overseas were mentioned 158 (27.4%), the U.K. government 147 (25.5%) and charitable funders 138 (23.9%) times. Grant award numbers were identified for 215 (37.3%) mentions, amounts were available in the public realm for 121 (21.0%) mentions. Based on the FOIs, until 01/2020, the European Commision (34.0%), Wellcome Trust (20.4%) and CEPI (17.5%) were the biggest funders of ChAdOx R&D. From 01/2020, the U.K. Department of Health and Social Care was the single largest funder (89.3%). The identified R&D funding was GBP104,226,076 reported in the FOIs, and GBP228,466,771 reconstructed from the literature search. Conclusions: Our study identified that public funding accounted for 97.1-99.0% of the funding towards the R&D of ChAdOx and the Oxford-AstraZeneca vaccine. We furthermore encountered a severe lack of transparency in research funding reporting mechanisms.