Vaccine "critical" for protecting mother and infants: study

By Sheilah Downey

Though pregnant women are considered at particularly high risk of disease and death from the flu, historically they have the lowest rate of vaccination of all adults, say researchers.

In a review of vaccinations of pregnant women between 1964 and 2008, no evidence was found to show an increased risk of maternal or fetal complications from vaccines, said researchers in the online edition of the  American Journal of Obstetrics and Gynecology.

"Healthcare providers will play a key role in women's decisions about whether or not to be vaccinated against H1N1," said senior author Dr. Saad B. Omer, of Emory's Rollins School of Public Health, in a press release.

"There is substantial evidence that vaccination is not only safe for pregnant women but that it is critical for protecting women and their infants against serious complications from the flu," said Dr. Omer.

Dr. Omer said that physicians and other health care providers should discuss the benefits and risks of vaccination with patients to alleviate unfounded fears.

Data from the Centers for Disease Control showed that in the spring of this year, before the vaccine became available, 32 percent of the 34 pregnant women with H1N1 had to be hospitalized. Pregnant women accounted for 13 percent of all deaths from the virus.

During the 1918 pandemic, before vaccine was available, half of infected pregnant women developed pneumonia and of those almost half died, said researchers. In the 1957 pandemic, almost half of all women of childbearing age who died were pregnant.

Most of the women who died during each of the pandemics, said researchers, were healthy before being infected with the virus.

Pregnant women are in the highest priority group recommended by the CDC to receive the H1N1 vaccine.

"During seasonal influenza epidemics, previous pandemics and with the current influenza A (H1N1) pandemic, pregnancy places otherwise healthy women at risk for serious complications from influenza, including death," said lead author Dr. Pranita D. Tamma, of the Division of Pediatric Infectious Disease at Johns Hopkins Children's Center.

Although pregnant women do not have higher incidence of flu than other women, it is the changes in the immune system during pregnancy that cause complications.

According to researchers, one previous study showed that healthy pregnant women are 18 times more likely to be hospitalized from flu that healthy non-pregnant women. Pregnant women with other medical problems are considered at even greater risk.

The research team also reviewed the safety concerns of thimerosal in vaccines and found no causal link between thimerosal and complications in infants.