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 Doctors recommend flu vaccinations for pregnant women because the
virus is linked to complications like preterm births, and because it
helps protect babies from catching the flu before they’re able to
get vaccinated at six months of age.
Before six months, babies born to vaccinated mothers were about 64
percent less likely to have flu symptoms and 70 percent less likely
to have confirmed infections than infants born to women who didn’t
get vaccinated during pregnancy, the study found.
“This large study provides more evidence that when women are
immunized against influenza during pregnancy, their infants are much
less likely to be diagnosed with influenza in their first six months
of life,” said lead study author Dr. Julie Shakib, of the University
of Utah in Salt Lake City.
But overall, just 10 percent of mothers reported getting the flu
vaccine during pregnancy, the study also found.
“Pregnant women may be concerned about harm, but they need to
understand that there is strong evidence that getting vaccinated
against influenza during pregnancy protects both themselves and
their babies from serious harm,” Shakib added by email.
To assess the prevalence and outcomes of flu vaccination during
pregnancy, Shakib and colleagues analyzed data gathered from 2005 to
2014 on almost 500,000 mothers and babies.
At the time of delivery, researchers asked women if they’d been
vaccinated during pregnancy. Roughly 23,000 women said they had done
this, while about 222,000 said they had not.
In the first six months of life, 32 infants born to vaccinated women
developed flu-like symptoms, compared with 834 babies born to
unvaccinated mothers, researchers report in the journal Pediatrics.
During those first six months, 20 babies born to vaccinated women
had laboratory-confirmed influenza, as did 638 infants whose mothers
didn’t get vaccinated, the study also found.
Researchers also looked at how waves of pandemic H1N1 strains of
influenza circulating in 2009 and 2010 influenced vaccination during
pregnancy.
Over four flu seasons before the pandemic, about 2.2 percent of
mothers got vaccinated during pregnancy. Afterward, the average
vaccination rate rose to 21 percent, with more than half of pregnant
mothers getting the flu vaccine during the final flu season in the
study.
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One limitation of the study is its reliance on mothers to accurately
recall and report whether they got vaccinated during pregnancy, the
authors note. They also lacked data on when in pregnancy women
received vaccines, or what strains of the virus were covered by the
inoculations.
Even so, the study adds to a growing body of evidence showing how
well flu vaccination during pregnancy works for protecting babies
against the virus, said Dr. Matthew Kronman, an infectious disease
specialist at Seattle Children’s Hospital and the University of
Washington who wasn’t involved in the study.
“We know that pregnant women and infants are at especially high risk
of severe disease with influenza,” Kronman said by email. In the
U.S. alone, about 100 to 150 children die of influenza each year, he
added.
When pregnant women get the flu, they’re at increased risk for
hospitalization, intensive care and death compared to women who
aren’t pregnant, said Dr. Leonardo Pereira, a maternal-fetal
medicine specialist at Oregon Health and Science University who
wasn’t involved in the study.
“Non-vaccinated women who get the flu are also contagious and can
infect other people in the community,” Pereira added by email.
The flu risk begins even before women leave the hospital after
delivery.
“When a mother who refused the flu vaccine delivers, her newborn
baby is more likely to contract influenza and more likely to require
hospitalization compared to babies born to mothers who were
vaccinated during pregnancy,” Pereira said.
SOURCE: http://bit.ly/1NjjM5K Pediatrics, online May 3, 2016.
[© 2016 Thomson Reuters. All rights
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