Written by Colin McEvoy | December 9, 2025 | SHARE
WHO vaccine director Kate O’Brien spoke with Lehigh students and faculty about how immunization has transformed global health over the past half-century.
The World Health Organization’s top official on global immunization spoke at Lehigh University during International Education Week (IEW) to discuss how vaccines have reshaped global health over the past 50 years and where the field is headed next
Kate O’Brien, Director of Immunization, Vaccines and Biologicals at WHO, spoke to students, faculty, and members of the Lehigh community during a Nov. 18 event presented by Lehigh College of Health and the Lehigh University/United Nations (LU/UN) Partnership.
Vaccination is estimated to have saved about 154 million lives in the last 50 years, with measles vaccines alone responsible for roughly 60% of those deaths averted, O’Brien said. Immunization also offers one of the highest returns on investment in health, she added, preventing illness, disability, and huge economic costs.
“Immunization for all is humanly possible, and I hope this provokes and catalyzes some thoughts on your side of how you can contribute to this as well,” O’Brien said. “I just really, really want to encourage all of you who are sitting in the room, especially the young people: we need you in this field.”
O’Brien discussed Immunization Agenda 2030, a global strategy that seeks for everyone, everywhere, at every age to benefit from vaccines, with a key focus on reducing “zero-dose” children and improving equity and ensuring no one is left behind.
The world is currently on track to meet the plan’s goal of 500 new vaccine introductions throughout the world this decade. But many challenges pose threats to vaccination, including constrained funding, geopolitical instability, a rise in misinformation and disinformation, and eroding trust and political polarization.
“We have a set of listening tools that country programs can use to monitor what’s going on in social and regular media, so they understand what’s being promulgated with respect to misinformation and disinformation,” O’Brien said.
“It’s really about meeting people where they’re at and answering their questions in an honest and transparent way, while making sure they have broad access to accurate, credible information,” she said. “First and foremost is recognizing that individuals are deeply wanting accurate information.”
Since the 1970s, childhood vaccine coverage has risen from about 5% to about 85%, contributing to major drops in infant mortality and big gains in life expectancy, O’Brien said. Vaccines are estimated to account for about 40% of the reduction in infant mortality, and a child under age 10 in 2024 is about 40% more likely to survive to their next birthday than in a world without vaccines since 1974.
Immunization also offers one of the highest returns on investment in health, with roughly $21 saved in illness costs per $1 invested, and about $54 when broader statistical life-value approaches are used.
“When you compare that with the return on investment of public infrastructure, preschool education, or community health workers — which are also highly valuable interventions — immunization is still among the most cost-effective,” O’Brien said.
Another goal of the Immunization Agenda 2030 is to halve the amount of zero-dose children in the world from about 12.9 million in 2019 to about 6.5 million by 2030. However, the COVID-19 pandemic increased rather than decreased the number of zero-dose children due to the diversion of health workers and systems toward pandemic response.
“The immunization program took a major hit in countries around the world because the workforce that deploys vaccines, and the whole effort on vaccines was deployed to try to save people from COVID-19,” O’Brien said. “So, despite improvements since the end of the pandemic, the world remains off track to reduce the number of zero-dose children by 50% by 2030.”
O’Brien’s presentation was one of several events included in Lehigh’s week-long International Education Week celebration. Organized by Lehigh’s Office of International Affairs (OIA), IEW is a nationally-recognized initiative that celebrates the ongoing importance and impact of international education and exchange worldwide.
OIA and the College of Health regularly collaborate on initiatives that advance the college’s mission to prepare leaders, address the growing needs of the health sector, and improve lives worldwide. The partnership focuses on global experiential learning, integrating international perspectives into the curriculum, and advancing research connections through Lehigh’s ties to WHO and the United Nations.