Influenza Vaccine to Protect Mothers and Their Babies FREE

Pregnant women are advised to receive influenza vaccine (a flu shot) each year because influenza infection can be more severe when it occurs during pregnancy. Antibody (disease-fighting protein) that is produced in pregnant women after they receive influenza vaccine can not only protect them from influenza but can pass through the placenta to the fetus and protect their newborn babies from influenza as well. A new pandemic strain, influenza 2009 A(H1N1), appeared worldwide in 2009. Pregnant women were reported to be at especially high risk for complications and death from this new strain of influenza.

To see whether pregnant women who received a newly developed vaccine against influenza 2009 A(H1N1), called A(H1N1v), produced enough antibody to be protected against infection with influenza and whether the antibody would be passed through the placenta to the fetus in protective levels.

Healthy pregnant women were enrolled in the study between weeks 22 and 32 of their pregnancies and followed until 3 months after delivery. They received a single injection of A(H1N1v) vaccine in the arm.

Blood was periodically drawn from pregnant women after they received the vaccine, when they gave birth, and 3 months later. At delivery, blood was also drawn from the umbilical cord after it was cut. The blood was tested to determine the levels of antibody against influenza 2009 A(H1N1) in the mothers and in the cord blood. The level of antibody in cord blood reflected how much was present in the blood of the newborn baby.

Antibody levels considered high enough to protect against infection with influenza 2009 A(H1N1) were found in the blood of almost all the mothers and babies. Although some serious adverse events occurred in mothers and babies after vaccination, an expert committee did not consider any to be related to the vaccine. No documented cases of influenza occurred in the mothers or babies.

Only healthy women at 22 weeks of pregnancy or beyond were included in the study. Too few women were studied to determine whether the vaccine could have caused uncommon side effects.

After pregnant women receive a single dose of influenza A(H1N1v) vaccine, they and their newborn babies acquire levels of antibody that should protect them from being infected with influenza 2009 A(H1N1). The influenza vaccine being given for the 2011 to 2012 influenza season is directed against both influenza 2009 A(H1N1) and seasonal influenza; thus, women need to receive only 1 injection to protect against both types of influenza.