Sabra Klein is an American microbiologist and a Professor of Molecular Microbiology and Immunology at the Johns Hopkins Bloomberg School of Public Health. Her research focuses on understanding the impact of sex and gender on the immune system, particularly in the context of infectious diseases. Klein's studies have delved into how biological sex and age influence the efficacy of influenza vaccinations, shedding light on the differing immune responses between men and women. Notably, during the COVID-19 pandemic, she investigated the reasons behind the differing outcomes of the virus between men and women, identifying biological and behavioral factors contributing to this phenomenon. Klein's extensive research has led to significant contributions in the field of immunology, earning her recognition as a Fellow of the American Association for the Advancement of Science in 2022. Additionally, she is known for her efforts in promoting women in the sciences, having established the Klein-Maloney Fellowship for Women in the Sciences with her husband, Drew Maloney. Her work has been published in prestigious journals and has made a substantial impact on our understanding of immune responses and infectious diseases.