Q:Information:  - The Johns Hopkins Bloomberg School of Public Health (JHSPH) is part of Johns Hopkins University in Baltimore, Maryland, United States. As the first independent, degree-granting institution for research and training in public health, and the largest public health training facility in the United States, the Bloomberg School is a leading international authority on the improvement of health and prevention of disease and disability. The school's mission is to protect populations from illness and injury by pioneering new research, deploying its knowledge and expertise in the field, and educating scientists and practitioners in the global defense of human life. The school is ranked first in public health in the "U.S. News and World Report" rankings and has held that ranking since 1994.  - The Johns Hopkins University (commonly referred to as Johns Hopkins, JHU, or simply Hopkins) is an American private research university in Baltimore, Maryland. Founded in 1876, the university was named for its first benefactor, the American entrepreneur, abolitionist, and philanthropist Johns Hopkins. His $7 million bequestof which half financed the establishment of The Johns Hopkins Hospitalwas the largest philanthropic gift in the history of the United States at that time. Daniel Coit Gilman, who was inaugurated as the institution's first president on February 22, 1876, led the university to revolutionize higher education in the U.S. by integrating teaching and research. Adopting the concept of a graduate school from Germany's ancient Heidelberg University, Johns Hopkins University is considered the first research university in the United States.  - Public health refers to "the science and art of preventing disease, prolonging life and promoting human health through organized efforts and informed choices of society, organizations, public and private, communities and individuals." It is concerned with threats to health based on population health analysis. The population in question can be as small as a handful of people, or as large as all the inhabitants of several continents (for instance, in the case of a pandemic). The dimensions of health can encompass "a state of complete physical, mental and social well-being and not merely the absence of disease or infirmity," as defined by the United Nations' World Health Organization. Public health incorporates the interdisciplinary approaches of epidemiology, biostatistics and health services. Environmental health, community health, behavioral health, health economics, public policy, insurance medicine, mental health and occupational safety and health are other important subfields.  - Katherine L. O'Brien is a recognized international expert in the areas of pneumococcal epidemiology , pneumococcal vaccine trials and impact studies , and surveillance for pneumococcal disease . She is also known as an expert in infectious diseases ( including pneumonia and diarrheal diseases ) in American Indian populations . She is a pediatric infectious disease physician , epidemiologist , and a Professor at The Johns Hopkins Bloomberg School of Public Health in the Department of International Health . She is the head of the Infectious Disease Group at the Center for American Indian Health and is the Deputy Director of the International Vaccine Access Center , an organization dedicated to accelerating global access to life - saving vaccines .    After reading the paragraphs above, choose the best answer for the entity that related to 'katherine o'brien' with the relationship of 'employer'.  Choices: - heidelberg university  - johns hopkins university  - life  - school  - united nations
A:
johns hopkins university