Flu vaccine during pregnancy protects mother and child from infections--study

According to researchers, pregnant mothers who get vaccinated could be shielding their infants from respiratory infections for up to six months.

Findings reveal that babies born to vaccinated mothers have lower risks of infections and hospitalizations and have a higher natural immunity passed on to them through the mother’s antibodies.

Lead researcher Dr Angelia A. Eick, of the Center for American Indian Health, Johns Hopkins Bloomberg School of Public Health, Baltimore stated, "Influenza virus infection in infants is generally more frequent among those aged 6 to 12 months than in the first six months of life, potentially owing to the protection conferred by maternal influenza antibodies acquired transplacentally or through breastfeeding.

"However, during severe influenza seasons, morbidity and mortality rates among infants younger than 6 months have been reported to exceed those of older infants."

Researchers found a 41 percent lower risk of lab-confirmed flu infections and a 39 percent reduced risk of hospitalization from flu illness in infants of vaccinated mothers

A non-randomized observational study conducted
In order to assess the protective benefits conferred to infants from maternal vaccine, the researchers conducted a non-randomized observational cohort study from November 2002 to September 2005.

The study included a group of 1,160 women at the Navajo and White Mountain Apache reservations who had delivered babies during one of the three influenza seasons.

The researchers opted for the Native American population because the rate of acute respiratory infection in the children is higher compared to the general population.

Half the mothers (573) had opted for the seasonal flu vaccine while pregnant and the other half (587) had declined the vaccine.

The participants were questioned in detail about various demographics, such as the vaccination status of other family members and flu risk factors.

Blood samples were collected from both the mothers and babies within 14 days of delivery, which were then analyzed for the presence of flu-like symptoms.

Revelations of the study
The analysis revealed that 17 percent of the infants were hospitalized for illness related to influenza, 36 percent had an outpatient visit for a respiratory problem, while 48 percent had no flu-like symptoms.

Researchers found a 41 percent lower risk of lab-confirmed flu infections and a 39 percent reduced risk of hospitalization from flu illness in infants of vaccinated mothers.

The blood samples of babies whose moms had received flu shots exhibited higher flu antibodies at birth and at two or three months of age, for all eight flu viruses tested.

However, by six months the antibodies had decreased and levels seen in the infants of both vaccinated and unvaccinated moms were similar.

The researchers concluded, "Although influenza vaccination is recommended for pregnant women to reduce their risk of influenza complications, these findings provide support for the added benefit of protecting infants from influenza virus infection up to six months, the period when infants are not eligible for influenza vaccination but are at highest risk of severe influenza illness.

"These findings are particularly relevant with the emergence of 2009 pandemic influenza A (H1N1) virus, which had a substantial impact on pregnant women and high hospitalization rates among young infants."

The findings appear in an early online edition of Archives of Pediatric and Adolescent Medicine.