Australasian Society for Infectious Diseases
Wednesday 20 March 2013, 05:24PM
Media release from Australasian Society for Infectious
The results of a study of the impact of a pertussis vaccine
"cocooning" strategy for adults in New South Wales shows that a
mother receiving the whooping cough vaccine before delivery lowers
the risk of whooping cough (pertussis) infection in very young
The research was carried out by Dr Helen Quinn, Professor Peter
McIntyre, Dr Tom Snelling and colleagues at the National Centre for
Immunisation Research and Surveillance for Vaccine Preventable
Diseases, Sydney, based at the Kids Research Institute and the
University of Sydney, New South Wales (NSW), Australia in
collaboration with New South Wales Health and presented at this
week's Annual Scientific Meeting of the Australasian Society for
Infectious Diseases (ASID) in Canberra, Australia.
In 2009, NSW Health implemented an initiative for preventing
whooping cough in young children by vaccinating the parents and
other adult carers, termed a 'cocooning' strategy. The strategy was
implemented primarily through general practice as well as maternity
units as part of a public health response to a large pertussis
epidemic that commenced in July 2008, and followed unfunded
national recommendations for cocoon immunisation in place since
Cases in the study included NSW infants aged four months and
younger diagnosed with laboratory-confirmed whooping cough during a
two-year period 2009-2011. For each case, up to four controls were
randomly sampled from a register of all NSW-born infants and
matched to cases by date of birth and area of residence.
Vaccination status of mothers was collected, in addition to other
information including demographic data and vaccination status of
other household members.
Data were available for 217 cases and 585 matched controls.
Overall, 75% of cases and 77% of control mothers had received
pertussis vaccine but only 47 (27%) of case mothers and 189 (41%)
of control mothers were vaccinated at least 4 weeks before the
index date, which was the onset of whooping cough in the case
infant. Importantly, 14% of case mothers and 26% of control mothers
were vaccinated before delivery, most within 2 years but up to 6
Significant risk factors for infant pertussis included large
households and less favourable socio-economic circumstances. After
adjusting for other significant risk factors, vaccination of the
mother before birth was significantly protective, with a reduction
in whooping cough risk of almost 50%.
Although fathers and grandparents of cases were also less likely to
have received timely vaccination, the study did not find any
significant additional impact after accounting for maternal
vaccination status. There was however protection from breast
feeding in addition to maternal vaccination. Importantly, the
siblings in case households were highly immunised, but
significantly more likely than control households to be in age
groups where immunity was likely to have waned (aged 2-3 years and
6 years and older).
Dr Quinn concludes: "Timely maternal vaccination was associated
with a significant decrease in risk of pertussis prior to
eligibility for the second infant dose at 4 months of age, with the
greatest benefit found in infants of mothers who received vaccine
before delivery. This is the first evidence of protection from
maternal pertussis vaccination prior to the current pregnancy. It
suggests that vaccination as part of pre-pregnancy planning would
have the greatest impact on whooping cough infection."
Key questions for local and international policy include whether
vaccination should become a permanent part of the immunisation
schedule or only be used in the context of an outbreak (as is
currently the case in the United Kingdom).
Click here or copy of the abstract.
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