Usually the advice for pregnant women is to avoid medications and vaccinations, but the inactivated flu vaccine is not only beneficial to the woman concerned, it can also protect her baby from infection during the first few months of life.

At this time of year, it is timely to remind pregnant women that this type of flu vaccine is recommended for them and is safe and effective. Early vaccination can provide protection against flu for the entire 2016/2017 flu season.

Most countries in the world recommend the inactivated flu vaccine to pregnant women who are at risk of severe illness due to getting flu, usually because of another underlying illness. Some, like the USA, recommend the vaccine to all pregnant women regardless of the trimester of pregnancy, other countries recommend influenza vaccination in the second and third trimester.

Despite this, uptake of the vaccine by pregnant women is generally low and this is why Professor Susanna Esposito (Università degli Studi di Milano, Fondazione IRCCS Policlinico Milan, Italy), who leads EVASG, is highlighting the benefits of the flu vaccine and recommending that all pregnant women get their flu shot as soon as it becomes available.

Benefits for a pregnant woman and her baby

·    The inactivated flu vaccine is safe for pregnant women and does not harm the foetus. It protects the mother against flu for the season she is pregnant, making it less likely she will develop influenza-related complications and hospitalisation.

·    The inactivated vaccine itself does not pass into the blood system of the foetus, so the vaccine is safe for both mother and baby. 

·    After vaccination, antibodies that develop in the mother’s blood pass through the placenta into the baby’s system, conferring secondary immunity that lasts for the first few months of life. The mother’s vaccination therefore protects her baby from getting flu once its born.

·    The protection for very young babies is particularly important because no flu vaccine is approved for use in infants under 6 months old. Unvaccinated babies born to unvaccinated mothers have little with which to fight a flu infection. Babies aged 0 – 5 months are five times more likely to be hospitalised due to flu than children aged 6 – 23 months. Mortality rates are also the highest in this age group compared to any other with 0.88 deaths per 100,000 children infected.

As many as 30% of children are infected with the flu virus every season. As Professor Esposito explains, “the impact of the infection is greatest in children under 6 months, 228,000 of whom are hospitalised every year worldwide. In the USA, where medical technology is arguably the most advanced in the world, over 500 children have died from influenza in the last four seasons.”

In addition to encouraging uptake of the current flu vaccines by pregnant women, Professor Esposito also recommends that future vaccines are developed to improve infant protection. “More infants could be protected if preparations that evoked a stronger immune response in the mother were formulated; this is crucial as we are still some way from developing a flu vaccine that is safe and effective for children under 2 years.”

ESCMID is a non-profit organization dedicated to improving the diagnosis, treatment and prevention of infectious diseases in Europe and beyond. The Society promotes and supports research, education and training and shares good medical practice in the infection disciplines to build capacity throughout the world. www.escmid.org

EVASG, the ESCMID Vaccine Study Group is working with other Scientific Societies (WAidid, ESPID, WSPID, ISPPD, ISID) on new guidelines regarding maternal immunization. This will take into account evidence from recent papers published on this topic and on the new vaccines that have become available in the last few years. The document will be ready for the end of 2017.

Professor Esposito’s paper in a leading international journal on the emerging problems surrounding protection of children against influenza will be published later this year.