Women are underrepresented in Science, Technology, Engineering and Mathematics (STEM). There are many initiatives which have been implemented in efforts to change this imbalance, including in primary, secondary and third-level institutions. Some are supported by governments, for example, by Science Foundation Ireland in Ireland, by professional bodies, such as IEEE, and by companies. Initiatives are targeted at STEM in general, and at subsets of the discipline. In fact, there are many STEM intervention programmes worldwide from which we in software engineering can learn. The logistics around planning and implementing a STEM intervention programme are many. This is compounded when a programme must quickly pivot and change how it is provided due to external factors. While this paper presents our experience on one STEM intervention, the University of Limerick-Lero/Johnson & Johnson WiSTEM2D (Women in STEM, Manufacturing and Design) programme, it also discusses and describes the challenges and the opportunities that became apparent when it had to completely change how it was deployed and implemented due to the COVID-19 pandemic. CCS CONCEPTS ¿ Social and Professional Topics ¿ Professional Topics ¿ Computing Education ACM Reference format: Marie Travers, Ita Richardson and Linda Higgins. 2021. Challenges and Opportunities when Deploying a Gender STEM Intervention During a Pandemic. In Proceedings of GE@ICSE conference (GE@ICSE'22). GE@ICSE, Pittsburgh. USA, 8 pages. https://doi.org/10.1145/3524501.3527596