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Allyson Velez, assistant dean for operations and institutional giving, serves as the critical connector between the team’s internal and external fundraising functions and key advisor on corporate and foundation donors and prospects. Before joining Columbia Mailman in 2022, Ms. Velez was with the Guttmacher Institute in various roles for more than 15 years, most recently as director of institutional giving, overseeing a period of major growth in the organization’s funding from foundations, foreign governments, and multilateral agencies. Ms. Velez has also held positions at the United Nations Population Fund (UNFPA), the Office of Congresswoman Carolyn Maloney, EMILY’s List, and the Institute for Democracy Studies. She earned a BA in public policy studies from Duke University and a master of public policy from Georgetown University. A native New Yorker, Ms. Velez currently lives in Manhattan with her husband, two children, and their pittie Pluto. She is a proud Columbia Engineering parent (’28 SEAS). 

Katie Mayfield, senior director of development, leads the individual major gift development efforts, reporting directly to the associate dean for development and alumni relations. With extensive experience in academic fundraising, donor relations, and strategic leadership, Katie is committed to advancing public health initiatives through impactful philanthropy.

Before joining Columbia Mailman, Katie served for five years as director of development at Rutgers Health, where she led fundraising efforts for both the School of Public Health and the School of Health Professions. In close collaboration with the deans, Katie significantly enhanced support for scholarships, health equity initiatives, and transformative research through major and principal gifts. In recognition of her impactful leadership and success, Katie was promoted to senior director shortly before she joined Columbia Mailman.

Katie’s academic background includes a master of arts in anthropology and PhD candidacy from Rutgers University, where she was a National Science Foundation Graduate Research Fellow. She also holds a bachelor’s degree in international affairs and women’s studies from the University of Georgia. In her early career, Katie spent five years in international development, working across Ghana, Nigeria, Kenya, Tanzania, and South Sudan, where she gained valuable global experience that informs her work today.

Sebastian Deken (’16 SOA), director of development communications, joined Columbia Mailman in 2023. He previously spent more than five years as the associate editorial director in the Development Division of Planned Parenthood Federation of America and the Planned Parenthood Action Fund, five years in board relations and special projects in the Department of External Relations and Development at  Columbia Business School, two years as a client account specialist at Cleary Gottlieb, and two years supporting education and outreach programs at COCA, a community arts center in St. Louis.

Sebastian earned his BA in music and French language and literature at Washington University in St. Louis, and he holds an MFA in nonfiction writing from Columbia University School of the Arts. He is the author of Final Fantasy VI (2021, Boss Fight Books), a ludomusicological study of the 1994 video game of the same name. A native of St. Louis, he now proudly lives in Queens with his husband Brett and his cats Gene Parmesan and Deloris Van Cartier.

David Huggins, major gifts officer, cultivates relationships with donors and secures major gifts to advance the School’s mission of improving global health. He has been with Columbia since April 2024.

David is a seasoned development professional with over 14 years of experience in frontline fundraising. He began his career in higher education with positions at New York University and Yeshiva University. He then joined Pace University's College of Health Professions as a major gift officer, where he focused on securing scholarships and legacy gifts from nursing and physician-assistant alumni.

Transitioning to the nonprofit sector, David served as the director of development at Public Health Solutions. He spearheaded fundraising efforts, organizing successful events and raising over $1 million in unrestricted funds for its gala. He then brought his expertise to the YM & YWHA of Washington Heights and Inwood as the manager of grants and institutional giving. In this role, he managed a substantial grant portfolio and secured critical funding, including a $1 million U.S. Department of Labor award to establish a workforce development center. David holds a master of social work degree and an undergraduate degree from Yeshiva University. He believes that genuine relationships and attentive listening are the keys to successful fundraising. In his free time, he enjoys reading Louise Penny novels and gardening.

Seble Lemma, senior associate director of donor relations, joined Columbia Mailman in October 2023. Prior to this, she served as development manager at Craig Newmark Graduate School of Journalism at CUNY, and before that spent more than five years as business development and operations manager at Helen Keller International. Before moving to the east coast, she lived in southern California where she worked as donor relations officer at the University of California and the California State University systems. Seble was born and raised in Ethiopia and is a graduate of the University of California, Los Angeles, with a BA in history. She currently lives in New Jersey.

Breanna Patterson (’24 SIPA), major gifts officer, has been with Columbia Mailman since 2022. Before this role, she spent three years at Columbia Business School working in both corporate relations and individual giving. At the Business School, she also managed the David and Lyn Silfen Distinguished Leadership Series, which hosted speakers such as Reed Hastings, the co-founder and co-CEO of Netflix, and Ajay Banga, former president and CEO of Mastercard. Before Columbia, Breanna worked in the legal sector and with various nonprofit organizations.

Breanna earned an MPA from Columbia University School of International and Public Affairs and received a BA in English from the University of Connecticut, Storrs. Breanna is originally from Greenwich, Connecticut. She enjoys reading, writing, painting, and traveling.