Neonatal pertussis, cocooning and maternal immunization

Abstract

The rising incidence of whooping cough, a highly contagious infection caused by Bordetella pertussis, is particularly significant for young infants who have the highest risk for morbidity and mortality. The pertussis resurgence has led to a shift in primary prevention relying on childhood vaccination to a cocooning strategy, that is, vaccination of close contacts of newborn infants (new mothers, fathers, grandparents, siblings, caretakers, etc.), thereby reducing pertussis exposure. Immunization of women during pregnancy rather than during the immediate postpartum period (the initial cocooning recommendation) appears to be a better approach by directly providing protection through transplacental transfer of maternal vaccine-induced antibodies. This article describes neonatal pertussis, cocooning as a means of reducing neonatal exposure to pertussis and maternal immunization as a means of protecting young infants against pertussis infection.

Pertussis vaccines

“…The limitations associated with the two classes of vaccines (whole cell vaccines [WCVs] and acellular vaccines [ACVs]) that are currently available are considered [11,12]. Potential improvements to vaccines and vaccine schedules are outlined [13][14][15][16][17][18][19] as well as the challenges inherent in diagnosing pertussis [20].…”

The diagnosis and epidemiology of pertussis in Australia

“…4,21 The primary aim of pertussis immunisation is to protect young infants against severe Despite the well-established pertussis immunisation programs in Australia and overseas, infants younger than six months of age continue to be at highest risk of severe outcomes. 10,86,89,[103][104][105][106] In the future, new pertussis vaccines may be able to provide earlier and longer lasting protection by utilising live attenuated B. pertussis strains, novel soluble or micro-particle vaccine formulations, improved adjuvants, or mucosal delivery, [107][108][109] however as these novel vaccines may still be many years away, other strategies need to be considered to protect young infants. 10,61,103,105 The "cocoon" strategy, which attempts to protect newborn infants by immunising their close contacts, such as parents and other caregivers, has been proposed as a possible solution.…”

“…10,86,89,[103][104][105][106] In the future, new pertussis vaccines may be able to provide earlier and longer lasting protection by utilising live attenuated B. pertussis strains, novel soluble or micro-particle vaccine formulations, improved adjuvants, or mucosal delivery, [107][108][109] however as these novel vaccines may still be many years away, other strategies need to be considered to protect young infants. 10,61,103,105 The "cocoon" strategy, which attempts to protect newborn infants by immunising their close contacts, such as parents and other caregivers, has been proposed as a possible solution. 4,10,61,[110][111][112][113][114] Parents and siblings have been found to be the most likely sources of transmission to newborn infants, 59,61,[115][116][117][118][119] although healthcare workers are also a common source of infection.…”

“…Both maternal and neonatal vaccination are being assessed as possible solutions. 61,103,129,130,236,237 Assessment of the Public Health England maternal pertussis vaccination program (which commenced in 2012) found vaccine effectiveness of 91% against confirmed pertussis in infants younger than two months of age. 129,130 A birth dose of pertussis vaccine has also been shown to induce protective antibody responses, and therefore protection against pertussis, prior to six months of age, but so far study sizes have been small.…”

“…20 Both B. holmesii and B. parapertussis have been detected in B. pertussis outbreaks and are believed to contribute to pertussis notifications. [13][14][15][16][17][18][19][20]103,183 In 2013, only 7% of Australian laboratories reported using multi-target PCR assays that could distinguish between the Bordetella species, with the remaining 93% of Australian laboratories likely to return false positive results for B. pertussis in approximately 90% of cases. 13 As PCR assays are further improved and specialised to detect other species of Bordetella, such as B. holmesii and B. parapertussis, it may be possible to quantify the contribution of these species to pertussis notifications and assessments of vaccine effectiveness.…”