By Dr Melinda Heywood
BSC, MBBS(Hons), FRANZCOG
Obstetrician and Gynaecologist

As influenza season rapidly approaches, it is a timely reminder for pregnant women to have the flu vaccination, which should be given regardless of trimester.

The vaccination is essential for pregnant women, who can be more likely to become seriously ill, be admitted to ICU, or die from influenza when compared to the general population.  They are more susceptible to a severe clinical course due to the normal physiological changes associated with pregnancy, with increases in heart rate and respiratory rate, reduced lung capacity and changes in the immune system.  Interestingly, in the HIN1 pandemic of 2009, pregnant women accounted for 5% of the deaths from HIN1, but made up only 1% of the population. 

The Fluarix Tetra is an inactivate quadrivalent vaccine, and the vaccine is available free of charge for pregnant women under the National Immunisation Program in Australia.  Ideally all health care workers looking after pregnant women, as well as their household contacts and relatives, should also be immunised.  It is safe, with no increase in adverse effects in pregnant women when compared with the general population, and can be given in any trimester.

Influenza vaccination also provides some protection for the baby from influenza for up to six months post delivery.

Women who catch influenza in pregnancy are at an increased risk of premature labour and delivery if they become infected.  Some studies have shown an increased risk of congenital anomalies, miscarriage and small for gestational age infants.

Importantly, early commencement of antiviral therapy is essential to reduce disease severity, and prevent ICU admission and death.  Therapy should be commenced once a clinical diagnosis has been made, and treatment should begin early, ideally within 48 hours of symptom onset.  Antiviral therapy may be of benefit if initiated after 48 hours, particularly in severe illness.  Pregnant women should be counselled to present to their GPs early for review if they become symptomatic.  The vaccine is not 100% effective, and there are case reports of infection post vaccine, so antiviral therapy should not be withheld from vaccinated symptomatic women.

Please encourage all pregnant women to be vaccinated, and to present to their GPs early if they have any symptoms of influenza.