Maternal vaccination

Background

Administering vaccines during a pregnancy is an important way to provide much needed protection at a time when a person is more vulnerable to severe disease and complications. Vaccination during pregnancy also has the added benefit of allowing the transfer of maternal antibodies across the placenta to the unborn baby which will provide short-term protection (passive immunity) in the first few months of life.

During pregnancy, many anatomical and physical changes occur to support the growth of a baby. Some of these changes include an increase in blood volume, increased demand on the heart and lungs, increased physical pressure placed on other organs due to an enlarged uterus, and changes to the immune system to ensure that the developing baby is not recognised as “foreign”. With these changes comes an increased risk of experiencing severe symptoms and complications if exposed to infections, in particular respiratory infections.

The administration of vaccines during pregnancy was historically avoided. However, as technologies have advanced, the benefits that some vaccines can offer when administered during pregnancy now far outweigh any theoretical concerns for safety. This has been particularly evident during pandemics such as H1N1 and COVID-19 where pregnant people were more likely to experience severe disease, hospitalisation and intensive care, affecting maternal and infant outcomes.

Recommendations

A thorough assessment of a person’s immunisation history and administration of any outstanding vaccines prior to pregnancy is an important part of preconception care. Administration of live‑attenuated vaccines (e.g. MMR/V) during pregnancy is contraindicated due to the theoretical risks associated with vaccine-related disease and its impact on a developing infant (see ‘Contraindicated vaccines’ below for more information). Live‑attenuated vaccines should be given a minimum of 28 days prior to conception, or must be withheld until after delivery.

During pregnancy, there are multiple inactivated vaccines recommended and funded on the National Immunisation Program (NIP). Other inactivated vaccines can be administered in special circumstances (e.g. medical risk factors, travel) but are not routinely recommended. Refer to the Australian Immunisation Handbook: Vaccines that are not routinely recommended in pregnancy for further information.

Correctly timing the administration of vaccines during a pregnancy is important and varies with each vaccine. Guidance on timing is based on whether the resulting immune response is intended to protect the mother, the infant, or both.

Influenza

Influenza vaccination during pregnancy is safe and strongly recommended to protect the mother from infection and avoid complications of disease. During pregnancy there is an increased effort required by the lungs. Influenza viruses affect lung tissue meaning infection adds further strain. As a result, pregnant people with influenza infection have a higher likelihood of requiring hospitalisation and intensive care than non‑pregnant people with influenza infection. Influenza infections during pregnancy also increase the risk of preterm birth, babies being born at low birthweight and stillbirths. 

Antibodies derived from maternal vaccination can also cross the placenta providing some protection to the infant. It is estimated that vaccination during pregnancy can reduce the risk of influenza infection by half in infants less than 6 months of age. This is important because influenza vaccines cannot be administered to infants until they are 6 months of age. 

Influenza vaccines are recommended annually and can be given at any time during a pregnancy. If a person is vaccinated before becoming pregnant, they should receive another dose when they are pregnant (minimum 4 weeks between doses). When a pregnancy crosses over influenza seasons, pregnant people are recommended to receive two vaccines, one for each season.  

Refer to MVEC: Influenza for up‑to‑date information on current influenza vaccines.

Pertussis

Pertussis vaccination during pregnancy is safe and effective and is recommended to protect both the pregnant person and, most importantly, the infant.

Infants under 6 months of age infected with pertussis have the highest rates of hospitalisation and death compared with people infected in other age groups. Symptoms include periods of intense coughing (paroxysmal coughing) with apnoea where infants stop breathing for a short period. There can be vomiting and difficulty feeding due to prolonged paroxysmal coughing episodes. Complications of pertussis in infants include pneumonia (lung infection), seizures and encephalitis (brain inflammation) which can be fatal. 

Infants require a 3‑dose course of pertussis vaccines (doses given at 6 weeks, 4 months and 6 months) to be considered fully protected. Vaccination during pregnancy can reduce the likelihood of infections occurring in infants who are too young to have completed this course by 90%. 

A single dose of vaccine (which is provided in combination with diphtheria and tetanus) should be administered between 20 and 32 weeks of gestation, in every pregnancy (including pregnancies that are closely spaced). If the pregnant person was vaccinated prior to pregnancy, they should still receive another vaccine within the pregnancy to ensure the infant will be passively protected. If an infant is born within 2 weeks of their mother’s vaccine, the passive immunity passed onto the infant may be suboptimal. 

Refer to MVEC: Pertussis for further information.

Respiratory syncytial virus (RSV)

Vaccination against RSV during pregnancy is recommended to provide passive immunity to infants. From 2025, vaccination during pregnancy will be funded on the NIP. 

Current data shows that almost all children will be infected with RSV by the time they turn 2 years old. Whilst most infections are mild, bronchiolitis (inflammation of the small airways) and pneumonia (lung infection) can occur and may lead to hospitalisation for supportive measures such as oxygen therapy and rehydration. Infants with specified risk factors such as preterm birth, cardiac conditions and chronic lung disease are more likely to experience severe disease. Clinical trials demonstrate that when vaccines are administered during pregnancy the risks of hospitalisation due to severe RSV infection is reduced by 57% in infants less than 6 months of age.  

A single dose of Abrysvo should be administered between 28 and 36 weeks’ gestation (NB: Arexvy is not registered for use in pregnancy). There is currently no recommendation for further doses in subsequent pregnancies; however, this may change as more data becomes available. When a pregnant person is vaccinated within 2 weeks of delivery, infant protection is likely to be reduced (many jurisdictions are funding infant RSV prevention programs for infants with medical risk factors and those with suboptimal passive protection). 

For more information refer to MVEC: RSV.

Contraindicated vaccines

The RSV vaccine Arexvy must not be administered to pregnant women due to a lack of safety and efficacy data. Should inadvertent administration occur, it should be reported to the adverse event reporting service in your jurisdiction and the patient should be informed using the open disclosure process.

All live-attenuated vaccines are contraindicated during pregnancy due to the potential risk to the unborn baby. In most circumstances the risk is hypothetical; however, there is insufficient evidence to support vaccination in this patient group.

If a live‑attenuated vaccine is inadvertently administered to a pregnant person, the person should be informed of the administration error and reassured using the open disclosure framework. The limited safety data from inadvertent administration of MMR and varicella vaccines is reassuring. The administration error should be reported to the adverse event reporting service in your jurisdiction.

Table 1: Live‑attenuated vaccines contraindicated in pregnancy

* oral vaccine
^ Pregnant people should be advised not to go to yellow fever endemic areas. However, if travel cannot be avoided a specialist consultation is advised.

Access

All vaccines recommended during pregnancy are funded on the NIP.

These vaccines are available via GP services, councils, hospital immunisation services, some pharmacies and other health services.

Commonly asked questions

Resources

• Australian Government Department of Health and Aged Care: How vaccines work for pregnancy and newborns (VIDEO)
• Australian Government Department of Health and Aged Care: Shared decision making guide for women who are pregnant ,breastfeeding or planning pregnancy
• Australian Immunisation Handbook: Vaccination for women who are planning pregnancy, pregnant or breastfeeding
• Raising Children Network: COVID-19 vaccination: preganancy and breastfeeding
• MVEC: Pertussis
• MVEC: Influenza
• MVEC: RSV
• MVEC: COVID-19
• MVEC: Immunosuppression in pregnancy and infant vaccine recommendations
• MVEC: Breastfeeding and immunisations