Dr. Alyssa R. Letourneau earned a Bachelor of Science in neuroscience from Brown University and her M.D.  from Yale University School of Medicine. She completed a combined residency in internal medicine and pediatrics at Massachusetts General Hospital, followed by a fellowship in infectious diseases at Massachusetts General Hospital and Brigham & Women's Hospital. During her training, she received the Edward Kass Award for Clinical Excellence from the Massachusetts Infectious Disease Society and earned a Master of Public Health from the Harvard School of Public Health. She then completed an additional year of advanced clinical training focused on the care of immunocompromised patients at Brigham & Women's Hospital and the Dana-Farber Cancer Institute.

Dr. Letourneau previously served for 10 years as Medical Director of the MGH Antimicrobial Stewardship Program and as co-chair of the Mass General Brigham Antimicrobial Stewardship and Infectious Diseases Quality Collaborative. She is currently a physician in the Division of Infectious Diseases at Massachusetts General Hospital and an Assistant Professor of Medicine at Harvard Medical School. She provides care to patients in both the inpatient and outpatient settings.

Her clinical interests include the care of immunocompromised patients, particularly those with leukemia or lymphoma, individuals who have undergone stem cell transplant or CAR-T therapy, and patients receiving immune-modulating therapies. She also has expertise in the management of multidrug-resistant organisms and mycobacterial infections.

In recognition of her commitment to education, Dr. Letourneau received the Mass General Brigham Infectious Disease Fellows Faculty Teaching Award in both 2021 and 2022. In 2023, she was elected a Fellow of the Infectious Diseases Society of America and was named a Top Doctor in Boston by Boston Magazine, an honor she has since received annually.