Dr Justina Tan obtained her medical degree at National University of Singapore in 2002. She completed her MRCP (UK) in 2005. She is also an educator with the Lee Kong Chian School of Medicine, Nanyang Technological University, and the Yong Loo Lin School of Medicine at the National University of Singapore.

As a recipient of a team Ministry of Health Manpower Development Plan (HMDP) scholarship, she completed an overseas attachment in Auckland City Hospital, New Zealand in September 2023 on Immunodeficiency disorders.

She is trained in musculoskeletal ultrasound and has special interest in early arthritis. She completed a NHG Health Clinical Practice Improvement Project in 2020 and received a Merit Award. She has worked on many collaborations with the TTSH Anti-Microbial Stewardship (ASP) pharmacists as she has special interest in Penicillin and Beta lactam allergy. She leads the Clinical Immunology & Allergy Service in the department.

Dr Tan is the current Programme Director of the NHG Clinical Immunology & Allergy training program, Clinical Competency Committee Chairperson for the NHG Rheumatology Senior Residency program and is actively involved in curriculum development for the Section of Clinical Immunologists and Allergists.

She is currently a board member on the Section of Clinical Immunologists and Allergists. She is also a member of the Singapore Society of Rheumatology (SSR) and Allergy and Clinical Immunology Society, Singapore (ACIS).