One of Mom’s Many Gifts to Her Baby: Maternal Vaccination

With maternal vaccination, mothers can pass life-saving antibodies onto their newborns.

In the third trimester of pregnancy, mothers give their babies something very important to prepare them before they enter the world: maternal immunity. Mothers transmit antibodies, proteins that fight off infections, through the placenta to their developing baby. Known as maternal immunity, these mother-to-child antibodies help protect an infant during the most vulnerable early months when the baby’s immune system has not yet developed.

But this does not protect the the majority of newborns over the period of greatest disease risk because the mother’s antibody levels are often too low to be protective once they’ve been passed to the baby. Worldwide nearly 700,000 newborns die each year due to infectious diseases such as pneumonia, sepsis, and tetanus. Many more are hospitalized and suffer long-term complications from infections. “RSV, for example, is responsible for nearly 200,000 infant deaths annually in developing countries and is the leading cause of infant hospitalization in the developed world,” says Kena Swanson, Senior Principal Scientist in Viral Vaccines at Pfizer’s Pearl River, NY Research and Development site.

The challenge with developing immune protection is also what makes it so sophisticated: It’s generally disease-specific. A mother needs to have acquired specific and protective antibodies through past exposure or by vaccination to be able to pass them to her baby. Of the five types of antibody classes, only one known as immunoglobulin G (IgG) is passed through the placenta to a baby, offering protection for up to six months.

A Mother’s Immunity Boost

In recent years, maternal immunization has been steadily gaining acceptance as a means to pass infection-fighting antibodies to newborns. Current research shows that vaccines are safe for pregnant women. After the H1N1 flu epidemic in 2009, both the Centers for Disease Control and Prevention and the American College of Obstetricians and Gynecologists recommended that all pregnant women receive the flu vaccine with each pregnancy. And with the recent uptick in whooping cough (pertussis) cases, the CDC also recommends that pregnant women receive a booster Tdap (tetanus-diphtheria-acellular pertussis) vaccine. A recent study of nearly 150,000 babies in California found that maternal vaccination is highly effective in protecting infants against whooping cough in the first two months of life. “Data and analyses like these show that scientific acceptance and policy changes can provide new opportunities to prevent life-threatening infections in babies through maternal immunization” says Kathrin Jansen, Head of Vaccines Research and Development at Pfizer.

Mom-Specific Vaccines

The next phase in fighting newborn infectious disease is to develop vaccines specifically for pregnant women. Various organizations, from the Food and Drug Administration and vaccine developers to the Bill and Melinda Gates Foundation and the World Health Organization have recognized the importance of producing vaccines explicitly approved for use in pregnant women for newborns, which has never been done before. Pathogens for which maternal vaccines are currently under development include: respiratory syncytial virus (RSV), group B streptococcus (GBS), and cytomegalovirus (CMV).

“Maternal vaccines have the potential to prevent devastating infant diseases for which treatment is very limited or non-existent for people in large parts of the world,” says Ed Buurman, Director of Bacterial Vaccines and Technology at Pfizer’s Pearl River site. “New maternal vaccines will potentially have a huge health benefit for millions of babies.”