In life, there are some who make an indelible impression on you. Individuals who have committed heroic acts, uplifted humanity, taken a courageous stand, excelled in the face of adversity. For me, that person was Dr. Maurice R. Hilleman, a microbiologist who developed a number of lifesaving vaccines for diseases like mumps, measles, chickenpox, pneumonia, meningitis, even influenza.

In fact, Dr. Hilleman developed eight of the 14 vaccines routinely recommended and he overcame immunological obstacles to combine vaccines, so that one shot could protect individuals against several diseases. During my tenure at Merck & Co., Inc. we became friends, and he taught me new things every single day.

I met Dr. Hilleman, a senior vice president for Merck research laboratories, for the first time on the third floor of his office at Merck & Co. in West Point, PA. We struck up a conversation where I was mesmerized by his expansive knowledge of several topics, ranging from property law to the Indian caste system, and, of course, medicine! He was avuncular.

And he was passionate about saving life. The quality and quantity of his scientific achievements were remarkable. His irreverent and irascible sense of humor stemmed from his gigantic intellect and wonderful wit. At 6-foot-1, Dr. Hilleman was always decked in a white lab coat and he exuded an aura that was only comparable to my childhood heroes, Dr. King, and Atticus Finch.

He was a legend from humble beginnings, raised on a farm in Montana, and he credited much of his success to his work with chickens as a young boy, whose eggs formed the basis for a plethora of vaccines.

It is widely known in the medical community that in 1963, when Dr. Hilleman’s daughter Jeryl Lynn came down with the mumps, he cultivated material from her, and used it as the basis of a mumps vaccine. The Jeryl Lynn strain of the mumps vaccine is still used today in the trivalent (measles, mumps and rubella) MMR vaccine that he also developed. It is, in fact, the first vaccine ever approved incorporating multiple live virus strains.

Dr. Hilleman also developed a vaccine against Japanese B encephalitis to protect American troops during World War II. But perhaps his greatest achievement of which he was so very proud was when he and his group invented a vaccine for hepatitis B by treating blood serum with pepsinurea and formaldehyde. In 1986 it was replaced by a vaccine that was produced in yeast. This vaccine is still in use today.

By 2003, 150 countries were using it and the incidence of the disease in the United States in young people had decreased by 95%. Hilleman considered his work on this vaccine to be his single greatest achievement.

To know a great doctor is to learn. Robert Gallo, co-discoverer of HIV, the virus that causes AIDS, once said “If I had to name a person who has done more for the benefit of human health, with less recognition than anyone else, it would be Maurice Hilleman. Maurice should be recognized as the most successful vaccinologist in history.”

On August 30th, Dr. Hilleman would have celebrated his 99th birthday. To this day, I think of him and smile, grateful for the opportunity to have known him. It is because of his passion and tireless efforts that millions can live healthy, happy lives. Happy Birthday, my friend.