Women who are pregnant or have children under two are not as effective at fighting a vaccine caused by a rubella virus, according to a study from the CDC.
The vaccine is commonly used to prevent cervical cancer, measles, mumps and other childhood illnesses that are caused by rubella. But the experiment makes it clear that pregnant and breastfeeding women aren’t as effective at fighting those vaccines – at least as long as they stay healthy.
“Vaccines are designed to kill the virus,” said Simon Bond, lead author of the study and associate professor at Cornell University School of Public Health in New York. “We found that while one in four vaccinated and non-vaccinated pregnant women didn’t respond to the rubella vaccine in the first several weeks after vaccination, these women remained healthiest over the longer term.”
After random-digit dialing 10,000 women, who were either pregnant or nursing at the time, 6,073, or 40 percent, had babies by the first birthday and 1,888 pregnant and nursing women, or 59 percent, born in the U.S. over the previous 10 years.
After 10 weeks following vaccine delivery, 38 percent of the women born to vaccinated mothers did not respond to the rubella vaccine – compared to 19 percent of the non-vaccinated woman – with the illness lasting a median of 7.5 weeks.
But that numbers actually could have been higher, according to the study, which was published this week in the New England Journal of Medicine.
“We found that the protective value of the vaccine – or in fact the lack of effect – was lower than originally estimated, likely because a larger proportion of vaccinated than non-vaccinated women were severely ill, suggesting that the virus missed them and they were not able to prevent their illness,” said Bond.
Bond said pregnant and nursing women also were at a higher risk of having high fever or migraines following the vaccine delivery.
The results of the study also add to a growing debate about the ideal age for women to receive rubella vaccination.
In 2013, the FDA advised all pregnant women to get vaccinated, saying that “medically effective rubella vaccines have been widely approved and widely used in the U.S. and globally.”
The center for disease control and prevention at the CDC also recommends that pregnant women and breastfeeding mothers receive rubella vaccine.
But while the CDC study found that just over half of U.S. women are vaccinated, only around a quarter of babies born in the U.S. are vaccinated with that same vaccine for rubella.
The difference between what researchers found with rubella vaccine in this study and other vaccine for varicella, a.k.a. chickenpox, was a technique used in the recent CDC investigation.
Rather than requiring every pregnant and nursing woman with at least one child under the age of two to get the rubella vaccine for all later generations, the CDC recommends that at least one child younger than the age of 1 be vaccinated.
Bond said researchers would need to delve more deeply into the data to come up with more detailed explanation on how the pregnancy and nursing women fared in this experiment.
The study was funded by the National Institutes of Health.