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New Zealand has undergone three pertussis epidemics in the last 15 years. In the most recent, from 2011 to 2014, there
were on average 102 cases of pertussis per 100,000 population, with the primary burden of disease in infants aged six
months or less at a rate of 801 per 100,000.2 Vaccine coverage for infants from August 2011 to December 2013
was 75% in six month-olds, highlighting a gap in vaccination rates in infants even during an epidemic.2 The
lowest rates of pertussis vaccine coverage were seen in Northland and Waikato DHBs.2 Vaccination rates were
lowest, and pertussis rates highest, for Māori and Pacific children and children in lower socioeconomic circumstances.2
The case for maternal vaccination during pregnancy
The Tdap vaccine was subsidised in New Zealand from 1 January, 2013 for use in pregnancy during a pertussis epidemic.
Currently, maternal immunisation rates in New Zealand are reported to be poor, and have been identified as a target area
for improvement prior to the next pertussis epidemic.2
Many cases of pertussis occur in infants too young to have gained immunity from the present national immunisation schedule.
Maternal vaccination offers benefit to the infant as maternal antibodies cross the placenta and provide protection prior
to the first infant vaccination at age six weeks, as well as boosting maternal immunity to provide indirect protection
and “cocoon” the infant.2, 3 In October 2012, the Advisory Committee on Immunization Practices (ACIP) in
the United States recommended that all pregnant females should receive Tdap vaccination during pregnancy.3 This
advice was echoed by the Global Pertussis Initiative in 2015, which now recommends maternal vaccination during pregnancy
as the primary prevention strategy for reducing pertussis hospitalisation and mortality in infants.4
Maternal Tdap vaccination is highly effective at providing pertussis protection to infants too young to receive vaccination
An assessment of pertussis incidence during an outbreak in England, where vaccination rates reached 60% in pregnant
mothers by the end of the outbreak, suggests a vaccine efficacy of 90% for infants aged under two months when vaccination
occurs at least seven days before birth.5 Similar analyses from the United States show a vaccine efficacy
of 91% for infants aged two months or under.4 Protection is lower if the vaccine is given within seven days
Tdap vaccine safety during pregnancy
Some expectant mothers may be hesitant to take up Tdap vaccination during pregnancy due to fears of adverse effects.
Mothers can be reassured that real-world data from tens of thousands of women who have been vaccinated against pertussis
during pregnancy report that rates of adverse birth outcomes are similar between vaccinated and unvaccinated mothers.4 Infant
growth and development up to age 13 months has been assessed in one randomised controlled trial of maternal pertussis
vaccination, and found not to differ between infants born to vaccinated or unvaccinated mothers.6
Surveillance data from the United Kingdom including 20,074 pregnant females who received pertussis vaccination reported
no increased risk of a range of adverse pregnancy outcomes, including: stillbirth, maternal or neonatal death, pre-eclampsia
or eclampsia, haemorrhage, fetal distress, uterine rupture, placenta or vasa praevia, caesarean delivery, low birth weight,
or neonatal renal failure.7 In the United States, surveillance data from 123,494 pregnant females, 21% of
whom received Tdap, reported no differences in rates of preterm delivery, small for gestational age babies, or hypertensive
disorders between vaccinated and unvaccinated mothers.8 A small difference in rates of chorioamnionitis was
noted in this study - subsequent assessment of this study, however, and other data by the Centers for Disease Control
(CDC) and Global Pertussis Initiative, suggest that there is unlikely to be a causal association between pertussis vaccination
and chorioamnionitis.4, 9
As pertussis vaccination during pregnancy has only been recommended and taken up recently, there is little data available
regarding long-term health outcomes for children. However, parents can be assured that maternal vaccination offers immediate
protection to infants in the neonatal period and a reduced risk of the serious consequences of pertussis infection.
Offering Tdap vaccination to pregnant women
Key practice points:
- Clinicians should offer the Tdap vaccine to all pregnant mothers and for each pregnancy
- Vaccination should preferably occur at least seven days before birth, and is subsidised for women between 28 and 38
Vaccination between 28 and 38 weeks’ gestation may provide the greatest benefit by allowing transfer of maternal antibodies
close to birth.3 The maximal antibody response develops after two weeks, and evidence indicates the greatest
vaccine efficacy occurs when vaccination is given at least seven days prior to birth.3, 4
Clinicians can inform patients that they should expect local injection site pain and irritation, and may develop short-term
systemic symptoms. Adverse effects following Tdap administration include typical vaccine-associated symptoms, such as
local irritation, injection site pain, and possible systemic symptoms, such as headache, fever, and muscle pain.3,
For mothers who decline vaccination during pregnancy, an alternative strategy for the prevention of infant pertussis
is to “cocoon” the infant by providing booster vaccinations for close family members immediately after birth.4 Vaccination
of adult family members against pertussis is not subsidised, but if children aged under 18 years are unvaccinated or have
not completed the recommended pertussis vaccination schedule, they can receive funded catch up vaccinations under the
For further information on pertussis vaccination during pregnancy, see:
- PHARMAC. Decisions to list and amend restrictions on various pharmaceuticals. 2015. Available from:
www.pharmac.health.nz/news/notification-2015-07-17-various-pharmaceuticals/ (Accessed Jul, 2015).
- Kiedrzynski T, Bissielo A, Suryaprakash M, et al. Whooping cough—where are we now? A review. N Z Med J 2015;128:21–7.
- Centers for Disease Control and Prevention (CDC). Updated recommendations for use of tetanus toxoid, reduced diphtheria
toxoid, and acellular pertussis vaccine (Tdap) in pregnant women-Advisory Committee on Immunization Practices
(ACIP), 2012. Morb Mortal Wkly Rep 2013;62:131–5.
- Forsyth K, Plotkin S, Tan T, et al. Strategies to decrease pertussis transmission to infants. Pediatrics 2015;135:e1475–82.
- Amirthalingam G, Andrews N, Campbell H, et al. Effectiveness of maternal pertussis vaccination in England: an observational
study. Lancet 2014;384:1521–8.
- Munoz FM, Bond NH, Maccato M, et al. Safety and immunogenicity of tetanus diphtheria and acellular pertussis (Tdap)
immunization during pregnancy in mothers and infants: a randomized clinical trial. JAMA 2014;311:1760–9.
- Donegan K, King B, Bryan P. Safety of pertussis vaccination in pregnant women in UK: observational study. BMJ 2014;349:g4219.
- Kharbanda EO, Vazquez-Benitez G, Lipkind HS, et al. Evaluation of the association of maternal pertussis vaccination
with obstetric events and birth outcomes. JAMA 2014;312:1897–904.
- Datwani H, Moro PL, Harrington T, et al. Chorioamnionitis following vaccination in the Vaccine Adverse Event Reporting
System. Vaccine 2015;33:3110–3.
- Ministry of Health. Immunisation Handbook, 2014. Available from:
www.health.govt.nz/publication/immunisation-handbook-2014 (Accessed Jul, 2015).