Michiaki Takahashi, whose experience caring for his 3-year-old son after the boy contracted chickenpox led him to develop a vaccine for the virus that is now used all over the world, died Dec. 16 in Osaka, Japan. He was 85.
The cause was heart failure, said his longtime secretary, Maki Fukui.
In 1964, Dr. Takahashi, who had spent several years studying the measles and polio viruses in Japan, was on a research fellowship at Baylor Medical College in Houston when his son, Teruyuki, came down with a severe case of chickenpox after playing with a friend who had the virus.
"My son developed a rash on his face that quickly spread across his body," Dr. Takahashi recalled in a 2011 interview with The Financial Times. "His symptoms progressed quickly and severely. His temperature shot up and he began to have trouble breathing. He was in a terrible way, and all my wife and I could do was to watch him day and night. We didn't sleep. He seemed so ill that I remember worrying about what would happen to him."
"But gradually, the symptoms lessened and my son recovered," he added. "I realized then that I should use my knowledge of viruses to develop a chickenpox vaccine."
He returned to Japan in 1965 and within five years had developed an early version of the vaccine. By 1972, he was experimenting with it in clinical trials. Within a few years, Japan and some other countries had begun widespread vaccination programs. Yet the Food and Drug Administration did not approve the United States' first chickenpox vaccine until 1995.
The delay was caused by several factors, including concerns that the immunity created by the vaccine might not last long enough, that there could be unwanted side effects and, more generally, that chickenpox might not be a serious enough disease to warrant a vaccination program.
Chickenpox is caused by the varicella-zoster virus, a form of herpes. If a person contracts the virus, has an active infection and then recovers, the virus is not actually gone from the body. It can hide in nerve cells for years or decades, then emerge again to cause shingles, a painful condition that causes a skin rash and occurs mostly in adults.
Dr. Takahashi developed his vaccine by growing live but weakened versions of the virus in animal and human cells. The vaccine did not cause the disease, but it prompted immune systems to produce antibodies.
"It fools the immune system into thinking it has seen this disease before," said Anne Gershon, the director of the Division of Pediatric Infectious Disease at Columbia University Medical Center and a friend of Dr. Takahashi's.
Dr. Gershon said Dr. Takahashi's is "the only vaccine successful against any of the human herpes viruses."
In 2006, the Centers for Disease Control and Prevention began recommending a second dose of the vaccine. The CDC recommends that children receive their first dose when they are 12 to 15 months old and a second dose when they are 4 to 6 years old.
"Prior to the licensing of the chickenpox vaccine in 1995," the agency said, "almost all persons in the United States had suffered from chickenpox by adulthood."
Dr. Takahashi was born on Feb. 17, 1928, in Osaka. He received his medical degree from Osaka University in 1954. Before his work on the chickenpox vaccine, he collaborated on mumps and rubella vaccines. He later served on the board of directors of the Research Foundation for Microbial Diseases of Osaka University.