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my personal edition > vaccinology > news
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DGDispatch
Vaccinated Pregnant Women Protect Their Unborn From Acquiring Seasonal Influenza: Presented at IDSA
By Ed Susman
PHILADELPHIA -- October 31, 2009 -- Pregnant women who are vaccinated against seasonal influenza appear to gain protection against the viral infection for their child through the first year of life -- even when the child is too young to be vaccinated, according to a study reported here at the 47th Annual Meeting of the Infectious Diseases Society of America (IDSA).
Marietta Vazquez, MD, Yale University School of Medicine, New Haven, Connecticut, said that, if mothers-to-be were vaccinated, the risk of their newborns contracting influenza would be reduced by more than 80% compared with children whose mothers had not been vaccinated while pregnant.
The percentage of women who receive vaccinations against influenza while pregnant, however, "is dismal," Dr. Vasquez stated during a press briefing here on October 29.
She and her colleagues conducted a continuing case-control study of infants admitted to their hospital starting in 2000. Infants with confirmed influenza were matched with cases of infants admitted for reasons other than influenza infection.
"Influenza is a major cause of serious respiratory disease in pregnant women and hospitalisation in infants," she said. "Although influenza vaccine is recommended for pregnant women and children, it is not approved for infants less than 6 months of age. Placental transfer of antibodies to the fetus has been demonstrated in the past, but the few studies having examined the effectiveness of influenza vaccination during pregnancy have had inconsistent findings."
The goal of the current study was to compare the mothers -- using both questionnaires and medical records -- to see whether they were vaccinated during pregnancy, and, if so, how effective the influenza vaccine was in preventing hospitalisation due to laboratory-confirmed flu in the infants.
Dr. Vazquez interviewed the parents of the children to determine risk factors for influenza, including examination of the medical records of both mothers and children to determine prior vaccination against influenza. Respiratory samples were tested to compare subjects' influenza strains to those included in the vaccine.
The team identified 119 infants hospitalised with influenza. Just 5% of the mothers of these children had been vaccinated against influenza. On the other hand, 16% of the 172 mothers of control infants had received influenza vaccinations (P = .002).
The difference between the groups translates into an 80.4% effectiveness for reducing the risk of acquiring influenza for all nonvaccinated children (P = .005). When the data comparison was restricted to only children younger than 6 months -- the earliest age at which vaccination is recommended -- the effectiveness rate rose to 88.8% (P = .004).
Dr. Vazquez said the results might help persuade more women to get vaccinated. "If they're not getting vaccinated for themselves," she said, "maybe they'll do it for their babies."
[Presentation title: Effectiveness of Influenza Vaccine Given to Pregnant Women in Preventing Hospitalization in Their Infants. Abstract 704]
All contents Copyright (c) 1995-2009 Doctor's Guide Publishing Limited. All rights reserved.
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