A Conversation With D. A. Henderson

Samet, Jonathan M.

doi: 10.1097/01.ede.0000152117.09709.78
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Editors’ Note: Voices is a project of the journal to provide personal, historical and scientific perspectives on the field of epidemiology, as seen through the eyes of the field's most senior and accomplished practitioners. Subjects are selected by the Editors. Readers are welcome to nominate candidates for Voices.

This interview was conducted 26 June 2004 at Dr. Henderson's home in Baltimore, Maryland. D.A. Henderson has approved this transcript for publication.

D. A. Henderson's curriculum vitae is available with the online version of the Journal at www.epidem.com.

Correspondence: Jonathan M. Samet, The Johns Hopkins University, Bloomberg School of Public Health, 615 N. Wolfe St., Ste. W6041, Baltimore, MD 21205-2179; E-mail: jsamet@jhsph.edu

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Donald Ainslie Henderson was born in Lakewood, Ohio, on 7 September 1928. He received his medical training at the University of Rochester School of Medicine, and completed a residency in internal medicine in Cooperstown, New York. He joined the Centers for Disease Control (CDC) in 1955 where he helped to develop its surveillance programs as well as field studies of a number of vaccines. He became director of the CDC program to eradicate smallpox in 1965 and a year later was named director of the World Health Organization (WHO) smallpox eradication program. With the success of that program, he accepted the position of Dean at the Johns Hopkins School of Hygiene and Public Health in 1977, a position he held until 1990. In 1991, he was appointed to the White House Office of Science and Technology Policy, and from 1993 to 1995, he served as Deputy Assistant Secretary and Principal Science Adviser in the Department of Health and Human Services. From 1998 to 2001, Dr. Henderson was founding director of the Johns Hopkins Center for Civilian Biodefense Studies. Beginning in 2001, he was named principal science adviser to Secretary Tommy Thompson and director of the Office of Public Health Emergency Preparedness. He is now a resident scholar at the Center for Biosecurity of the University of Pittsburgh Medical Center. He holds 16 honorary degrees and has been decorated by 18 foreign governments. In 1986, he received the U.S. National Medal of Science and in 2002 the Presidential Medal of Freedom.

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JS: Most people do not start out to become epidemiologists. How did you come to this field?

DH: I became an epidemiologist by fortuitous circumstance. From childhood, I wanted to be a physician, following in the footsteps of my uncle. During college, an interest in management was whetted by a stint as editor of the college annual yearbook and, later, by the experience of founding a radio station, which I did with my roommate.

I went to medical school at the University of Rochester where we had little instruction in public health and none in epidemiology. Soon after arriving, I found that there was no student organization. I decided to start one. This led to several meetings with the Dean, and at one point, I said, “You know, I'd like to combine medicine and administration. How does one become a dean?” His response was, “No one has ever asked me that question.” His advice was “Take your time getting there as it is unlikely that you would ever successfully return to the clinic or laboratory after a deanship.” It was good advice, although I have discovered there are other interesting challenges after deaning.

As a senior I competed for a prize on the history of medicine and chose as a subject the 1833 cholera epidemic in Upstate New York. The prize of $200, to a penurious medical student, was the primary motive because I actually had little interest in infectious diseases. The study involved plotting cases and deaths by time, age, and geographic area based on surprisingly detailed newspaper records of the time. Instinctively, I was estimating survival curves and attack rates. I won the prize (although I believe I was the sole entrant).

The prize assumed a greater importance when I faced the military draft during internship. As an inexperienced new doctor, I would probably be assigned the task of admission physical examinations, a tedious job. A CDC officer came to our hospital to discuss the Epidemic Intelligence Service (EIS), a more attractive prospect than doing physical examinations. As it turned out, many were competing for the position. I cited my prize paper as evidence of my interest in infectious diseases and was accepted.

Alex Langmuir was Chief Epidemiologist at CDC. He had founded the EIS at the beginning of the Korean War as a rapid-response cadre should a terrorist release biologic weapons in the United States. After a month of EIS training (comprising basically “Epi 1” and “Biostat 1”), I was off to my first assignment. Preferences of new recruits were matched against the preferences of senior staff who would serve as mentors. On the list was Assistant Chief EIS Officer, described as a “gopher job” working with the Chief EIS Officer under Alex. I opted for this position, thinking that it would give me an opportunity to experience both administration and medicine, and I got the assignment. I was immediately sent to investigate a diphtheria epidemic, and when I came back, the Chief EIS Officer was packing his bags. I began to assume his responsibilities, with a very steep learning curve. I served as Alex's Deputy for 8 years, and we kept in very close touch throughout the rest of his life. He was an extraordinarily effective teacher but, at the same time, demanding, difficult, inspiring, and controversial.

JS: Who most strongly influenced your career?

DH: Alex, without question. Through him, I discovered the excitement and challenge of epidemiology and its special attraction in requiring solutions that bring together epidemiologic insights, clinical observations, sociologic characteristics, laboratory findings, and all matter of other insights in solving what are often wonderfully fascinating puzzles.

JS: Langmuir influenced many careers. Why?

DH: He made epidemiology exciting. He reveled in the practical experiences provided by fieldwork—what he termed “shoe leather epidemiology.” Every contact with him was a memorable experience because he challenged the accepted wisdom and willingly offered penetrating critiques of everyone's work. As part of the introductory course, he arranged for all class members to participate in a door-to-door survey. The realities, difficulties, and challenges of conducting interviews and the caveats implicit in the data were indelible experiences.

JS: Say more about the importance of collaboration and teamwork. Few epidemiologists work alone.

DH: Alex said that a good collaboration requires people with equivalent ego strength and intelligence and that teams work best when the individuals see the product as the primary objective rather than who gets credit for the work.

There was an exception to this adage. Alex made it clear that wherever we were working in the field—in local health departments or other countries—the option for senior authorship on a paper or report went to the onsite person, the local health officer. Alex regularly pointed out that these were the people who were in the area for the long term, and to help strengthen their position, they needed credit and proper recognition. This policy certainly helped assure good collaboration and avoided the fear that we CDC staff would “parachute in,” seize the data, and publish. I do not think this policy is still in effect.

JS: Which of your contributions would you most like to be remembered for?

DH: The most important are related to immunization. At the CDC, I participated in the initial field introduction of the Salk polio vaccine, then the oral polio vaccine, and next the measles vaccine. As Chief of the Surveillance Section, I oversaw studies to test the simultaneous administration of multiple antigens, these being particularly useful for developing countries. Then we began to undertake studies of smallpox vaccination using a new jet injector that could vaccinate 1000 persons per hour. Later, in the WHO, I chanced upon a new device, the bifurcated needle, which was still experimental but intended for use in multiple-pressure smallpox vaccination. I proposed its use instead for vaccination with multiple punctures. It worked well. It proved to be easy to teach, was rapid to execute, and required one fourth as much vaccine as the conventional technique. It was one of the key factors in the success of the eradication program.

When the smallpox eradication program started, its primary purpose, as I saw it, was not to eradicate smallpox. In one of my early letters from the field, I proposed that our most important contribution was to establish a system that could deliver a product throughout a country with assurance of performance through quality control methods and to measure its impact through surveillance. Smallpox vaccine was the obvious vehicle for this idea.

At the end of the third year of the program, almost no children in the developing world were getting vaccines other than smallpox. Under WHO, we convened an international meeting in 1970 and laid out what seemed to be a reasonable minimum number of vaccines for children throughout the developing world. This meeting laid the groundwork for the WHO Expanded Program in Immunization that the World Health Assembly endorsed in 1974. Progress was slow, but by 1990, the world was approaching the point at which nearly 80% of children in the developing world were being immunized for polio, measles, DPT, and BCG. Having increased from only 5% in 1974, this had an enormous impact on childhood fatality rates in many countries. It also stimulated renewed interest in other vaccination programs.

JS: What do you see as the differences in the field between when you started and now?

DH: When I started, there was much more emphasis on infectious disease epidemiology. In the late 1950s, it was increasingly perceived that infectious diseases in the industrialized countries had been effectively conquered. Support for research and education in epidemiology shifted toward the chronic diseases. Not until the 1980s and the advent of AIDS did interest and support for work in the infectious diseases begin to recover but, still, there are disappointingly few people and resources working in the field.

Another difference, as I see it, is that in the past, the tie-in among field epidemiology, policy, and action was much more direct. Although the problems today may be more complex, it seems to me that undue efforts are directed toward assessing marginal differences and relationships with elaborate means. In part, I believe this reflects a reluctance of many epidemiologists to cope with the sometimes difficult and uncertain challenges of field epidemiology. Many prefer to use a computer and mine data from behind a desk or to develop hypothetical models.

JS: What is your assessment of the current state of the field?

DH: That is a tough question, in part because once I became Dean in 1977, I was less directly involved day-to-day in epidemiologic studies and I was less often able to attend epidemiologic meetings. My perception, as a now more distant observer, is that much being done in epidemiology seems to be marginally relevant. There could be better ties between epidemiology and the research scientists in identifying and using new technologic tools and methods. I am particularly disturbed by the lack of scientific expertise, including epidemiology in particular, at the higher levels of government. Epidemiology, as the science of public health, should inform many decisions, but I do not see that happening. With respect to biologic preparedness, many priorities are being set by people who know little about the subject matter and who, even at higher levels of decision-making, have had little beyond high school biology.

JS: How do you find good research questions?

DH: An important component is for those concerned directly with coping with problems, be they clinical or public health, to be in continuing communication with basic scientists and engineers and to continually ask the question “Is there a better way to do what we are doing?” In the smallpox program, ideas for research came by multiple paths. For example, every 2 years we had a major research meeting where we brought together people in virology, epidemiology, and other areas and assessed our problems: What could be done to facilitate the program? Where are our principal barriers and who might have answers? Field staff was encouraged to undertake epidemiologic and operational studies and to write them up to share with others. For many whose native language was not English, we volunteered to edit reports and to distribute them to all program staff. Our goal was to provide at least 1 new paper every 3 weeks. Thus, there was a continuing flow of ideas and a stimulus to put more material on the table. At least once a year, we convened staff at least regionally and had them present reports for discussion. The result was that the program was in continual evolution.

JS: What have been your most influential papers?

DH: I think the most influential is the Big Red Book.1 It was critical that it serve an archival function because no one else knew the program or had the information available that we did. The book was intended to be both instructive and readable. The book is now out of print and recently, I was told that someone had obtained a copy on eBay for $800. The National Library of Medicine has put it on a web site so it is accessible.2

JS: And if you had to think of an unappreciated contribution?

DH: In 1959, Alex Shelokov and I wrote a Medical Progress Review for the New England Journal of Medicine on what we called “epidemic neuromyasthenia.”3 With a fellow EIS officer, I had worked up a big outbreak in Punta Gorda, Florida4 and so had Alex in Rockville, Maryland.5 These were, in effect, what we now call chronic fatigue syndrome, and they were clearly major outbreaks. From the epidemiologic characteristics, there was no question in our minds but that an infectious agent had to be the cause. However, as we pointed out, the signs of this disease were so evanescent and the symptoms so nonspecific that, for individual cases outside of an epidemic context, the syndrome was very likely going to end up as a sort of wastebasket diagnosis for many different diseases.

No viruses or other agents could be identified among the victims. We postulated that the agent might have been present only at the earliest stages and so might have been missed. We designed a study to implement at the onset of an outbreak so we could obtain specimens prospectively. However, we identified no further outbreaks over the next 7 years and, by then, I had left for the WHO. Despite our cautionary note, I am afraid the diagnosis is all too often uncritically applied and no real study such as we proposed has been carried out.

JS: This is the first time I have heard about this paper. It sounds as if you made a good prediction, that this would be a wastebasket syndrome we are still sorting out. What have been your interests outside of epidemiology?

DH: Outside of gardening, virtually nil. Every job I have had has offered more challenges and opportunities than I have been able to address. As I wrap up one problem, I find myself identifying other areas that need to be explored. After I left the White House staff, I decided I would return to golf, which I had played when I was much younger. I actually spent a week down at Pinehurst with a class, but I have not touched the clubs since. There has just been too much to do.

JS: Do you have any advice for young epidemiologists?

DH: I would recommend that they get field experience, actually collecting some of their own data, analyzing it, and writing it up. An international experience can be especially stimulating. Unfortunately, only a limited number even at the CDC get that experience today despite the fact that that sort of experience was once a core element in the training. As long ago as 1961–1966, when I was Chief of Surveillance, we had begun to have so many trainees that it was difficult to provide reasonable field experience for all of them. Since then, the Atlanta staff has grown almost logarithmically. More epidemiologists should be working at state health departments, city health departments, or abroad.

In the future, we are going to see many more individuals based abroad. Health and disease are global phenomena, of importance economically and to our own national security. In fact, arrangements are now underway to place epidemiologists in parts of South Asia, primarily because of the influenza threat. We need a more comprehensive international surveillance network and staff based where the problems are. The all-too-prevalent concept that one can fly in a team, do the work, and fly out again is the wrong way to go.

JS: Let me ask a question that you are probably as well positioned as anybody to answer. Have the academic world of epidemiology and the applied world gone in quite separate directions?

DH: Yes, to a regrettable degree. It is not only epidemiology, but schools of public health. My concern, when I accepted the deanship at Hopkins, was that the schools of public health were becoming primarily graduate schools, not professional schools. Could a faculty of surgery do research on surgery and teach surgery but perform no operations? They would be considered irrelevant. In schools of public health, we have all too many faculty who have never worked outside the academic world and have no experience either in operating a public health program or even participating in one. Such individuals often seem to be overrepresented on committees on appointments and promotions, and judge faculty only on the number of peer-reviewed papers, debasing those who have real-world experience. If schools of public health and departments of epidemiology are to prosper, they have to be relevant to the real world.

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1.Fenner F, Henderson DA, Arita I, et al. Smallpox and Its Eradication. Geneva: World Health Organization; 1988.
3.Henderson DA, Shelokov A. Medical progress: epidemic neuromyasthenia—clinical syndrome. N Engl J Med. 1959;260:757–764.
4.Poskanzer DC, Henderson DA, Kunkle EC, et al. Epidemic neuromyasthenia: an outbreak in Punta Gorda, Florida. N Engl J Med. 1957;257:356–364.
5.Shelokov A, Habel K, Verder E, et al. Epidemic neuromyasthenia: outbreak of poliomyelitis-like illness in student nurses. N Engl J Med. 1959;260:757–764.

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