If you find out you are pregnant after a rubella vaccination...? - Director's Blog



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If you find out you are pregnant after a rubella vaccination...?


Today I have chosen to address a pressing topic: the outbreak of rubella, also known as German measles, among adults in Japan today. I will save the fun topic for my next message.

Rubella is sometimes called the "three-day measles." In contrast to measles, which is characterized by high fever and a rash over the entire body for more than a week, rubella is a mild viral infection with symptoms of low-grade fever and a less conspicuous rash. This nature of the disease is indicated by its name "three-day measles." Symptoms generally remain mild, and for this reason, natural infection is often considered preferable over vaccination. This view is even held by some pediatricians, albeit a small number, who are specialists in this infection. Even so, although rare, it can also cause encephalitis and its after-effects. In the past, I also treated children who were troubled by the after-effects of rubella encephalitis.

The most serious problem with rubella is, however, the risk of congenital rubella syndrome that leads to hearing difficulties, eye abnormalities, and mental retardation in the fetus when a pregnant woman contracts rubella in the first trimester of pregnancy. In the past, junior-high aged girls were given rubella vaccination as a means of preventing congenital rubella syndrome. Reflecting this practice, over 70% of rubella patients are men, and 80% of these are men between the ages of 20 and 49.

Rubella infection among adults has become a major social and health problem today. Of course, this is a problem not only for the health of those infected, but also for other adults with whom they come into contact. The number of children with congenital rubella syndrome is also expected to rise as women in the first trimester of pregnancy who have not been vaccinated contract rubella.

Rubella can be prevented by vaccination, which means that by vaccinating unvaccinated adults, it will be possible to prevent an increase in children with congenital rubella syndrome. In other words, unvaccinated adults should be vaccinated against rubella. But, here we encounter new problems that we can neither anticipate nor ignore.

Take, for example, a case in which an unvaccinated woman discovers that she is pregnant after having been vaccinated. The rubella vaccine is a live vaccine in which an attenuated strain of the disease-causing virus (live) is injected, and immunity is acquired through the rubella virus contained in the vaccine. If a woman is vaccinated before knowing that she is pregnant, even though the virus in the vaccine is attenuated, the fetus will be infected with rubella virus. This is the reason that rubella vaccination is contraindicated when it is known that the woman is pregnant.


What then should be done when a women has been vaccinated for rubella before discovering that she is pregnant? About a half a year ago, I received the following e-mail from someone I did not know.

"Last month, I was vaccinated for rubella without knowing that I was pregnant. Today, I discovered that I am ten weeks pregnant. What is the risk of my child having congenital rubella syndrome? My gynecologist recommends an abortion. I am also concerned about the after-effects of an abortion and am having trouble coming to a decision."

While the rubella vaccination is contraindicated for pregnant women, this inquiry refers to a situation that is quite possible and likely to happen because pregnancy is not known until several weeks after conception. If there is any concern, one view might see abortion as the solution, but in the case of a woman vaccinated in the first trimester, there would be no need to worry if we knew the frequency of this leading to the congenital rubella syndrome in the fetus. This information is, however, available, and I replied to the inquiry as follows.

"I understand your concern. According to research in the textbook, "Epidemiology and Prevention of Vaccine-Preventable Disease," among children born to 321 women who were vaccinated for rubella in the first trimester of pregnancy before knowing they had conceived, none showed signs of congenital rubella syndrome. The above textbook clearly states that "women who know they are pregnant should avoid vaccination (the danger is logically possible), but there is no reason to have an abortion if vaccinated while pregnant. Some gynecologists in Japan recommend abortion, but this is not the case in the United States, and in my opinion, the more rational view is the one in the United States, which is based on the facts."

I recently received the following e-mail from this woman. "Thanks to your advice, I gave birth to a healthy baby boy. He was born because you kindly answered my inquiry although it was from a total stranger. Thank you very much."

In campaigns to encourage rubella vaccination in adults, we will certainly encounter more people like this woman who contacted me by e-mail. I hope that the information presented here will serve as a reference for them.

Sakakihara_Yoichi.bmp Yoichi Sakakihara
M.D., Ph.D., Professor, Graduate School of Humanities and Sciences, Ochanomizu University; Director of Child Research Net, Deputy Director of Japanese Society of Child Science. Specializes in pediatric neurology, developmental neurology, in particular, treatment of Attention Deficit Hyperactivity Disorder (ADHD), Asperger's syndrome and other developmental disorders, and neuroscience. Born in 1951. Graduated from the Faculty of Medicine, the University of Tokyo in 1976 and taught as an instructor in the Department of the Pediatrics before assuming current post.