Protecting pregnant women and their newborn from life‐threatening infections

Pertussis and influenza vaccinations should be incorporated into antenatal care and accurately documented

Vaccination of pregnant women protects them against influenza and pertussis, and also delivers protective antibody to their fetus, protecting infants when they are at the highest risk of life‐threatening disease but are too young to be vaccinated.1

Despite strong recommendations by advisory groups, including the World Health Organization, uptake of influenza vaccination by pregnant women, in particular, is low. In their study published in this issue of the MJA, Rowe and her co‐authors2 report that, after seven years of a program for vaccinating pregnant women in Victoria against influenza, coverage remains suboptimal (61% in 2017), but is higher for pertussis vaccination (82%), publicly funded since 2015. In England, the corresponding rates were 47.2% for influenza vaccination (2017–18 season) and 68.2% for pertussis vaccination (July–September 2018).3,4

Maternal vaccinations are not systematically documented in Australia or the United Kingdom. In England, most maternal vaccines are administered and systematically recorded in primary care, but delivery in maternity units, for example, is incompletely captured in the primary care records used for estimating coverage. Together with the different approaches to monitoring pertussis and influenza vaccination, this means that coverage may be underestimated. In Australia, the recording of maternal vaccinations in the pregnancy handheld record and perinatal data collection forms completed by midwives differs between states; as adult vaccinations are not associated with family or child care benefits or immunisation provider payments, reporting of maternal vaccinations to the Australian Immunisation Register is probably incomplete. This contrasts with the accurate recording of childhood vaccinations (94% program coverage at 12 months of age in Australia,5 93% in the United Kingdom),6 which is based upon national registers or local Child Health Information systems respectively.

Of major concern is the lower coverage among pregnant Aboriginal and Torres Strait Islander (Indigenous) women reported by Rowe and colleagues.2 Earlier studies have identified endorsement by health care providers as a strong indicator of maternal vaccination uptake.7 Pregnant women regularly visit their GP, midwife, and obstetrician for pregnancy care and education, trusting their advice about healthy pregnancy. Increasing the capacity of Indigenous Australian midwives to deliver maternal vaccinations may improve coverage among pregnant Indigenous women. Improving access by delivering vaccinations at antenatal clinics significantly improves coverage, with pregnant women 20 times more likely to be vaccinated against pertussis in vaccination programs delivered by midwives.8 A systematic review found that interventions which improve health care provider awareness of maternal vaccinations, such as electronic reminders and updates by email and at medical staff meetings, effectively increased maternal pertussis vaccination rates.8

Pregnant women are at greater risk of severe influenza infection, and have a greater risk of hospitalisation and higher mortality rates.9 Although vaccination prior to the peak influenza period is ideal, providers should ensure that pregnant women are vaccinated beyond the traditional influenza vaccination season so that they are protected all year round. As Rowe and colleagues conclude,2 system‐level structural changes are needed to improve maternal vaccination coverage, in addition to education about its risks and benefits.

In April 2016, advice on maternal pertussis vaccination was updated in the UK to extend the optimal window for vaccination from 28–32 weeks’ to 20–32 weeks’ gestation; that is, after the morphology ultrasound examination.10 This recommendation was informed by evidence that antibody titres are higher when pregnant women are vaccinated during the second trimester than during the third, and also provided greater opportunity for women to be vaccinated, thereby improving vaccination rates.11 Mean pertussis vaccination coverage was 75% during October–December 2016, 14 percentage points higher than during the equivalent period in 2015.12 In Australia, the Australian Technical Advisory Group on Immunisation has also recently recommended pertussis vaccination from 20 weeks’ gestation.13

Several new vaccines for pregnant women are in development. A large multicentre randomised controlled trial recently found that an investigational respiratory syncytial virus (RSV) vaccine for pregnant women was effective in reducing the number of hospitalisations of infants with severe RSV infections.14 As the morbidity of RSV is considerable — 80–90% of children are infected by 2 years of age,15 with high hospitalisation rates (and some deaths) of infants with underlying lung disease — there is likely to be considerable interest in preventing RSV disease in infants by vaccination during pregnancy. Group B streptococcal vaccines are also being tested in clinical trials. Most group B streptococcal infections are in newborns (early onset disease) and young infants (late onset disease); although infrequent, such infections have a case fatality rate of 6.8%.16 Although not currently recommended for pregnant women, other vaccines that could protect infants prior to scheduled vaccinations, including meningococcal vaccines, could be considered.

Pertussis and influenza vaccination coverage rates among pregnant women of 90% can be achieved, but would require systems for incorporating vaccinations into antenatal care and accurately documenting vaccinations during pregnancy in the pregnancy handheld record and perinatal midwife data collection forms. Embedding vaccination into standard pregnancy care, whether delivered by GPs, midwives or obstetricians, normalises the process, improves access to vaccination, and reduces the risk of missing opportunities for vaccination. This will enable targets to be reached in alignment with other routine antenatal pregnancy procedures.