title: Specific antibodies against vaccine-preventable infections: a mother-infant cohort study.
abstract: OBJECTIVE
  To determine maternal and neonatal specific antibody levels to selected vaccine-preventable infections (pertussis, Haemophilus influenzae type b (Hib), tetanus and pneumococcus).
  
  
  METHODS
  Prospective cohort study.
  
  
  METHODS
  A UK secondary care maternity unit (March 2011-January 2012).
  
  
  METHODS
  Mothers and infants within 72 h of delivery were eligible. Unwell individuals, mothers less than 18 years of age, and infants born at less than 36 weeks gestation, or weighing less than 2500 g, were excluded. HIV-infected mothers were included. 112 mother-infant pairs were recruited. Samples from 111 mothers and 109 infants (108 pairs) were available for analysis.
  
  
  METHODS
  Specific antibody levels were determined using standard commercial ELISAs. Specific antibody to pertussis antigens (PT and FHA) of >50 IU/ml, defined as 'positive' by the test manufacturer, were interpreted as protective. Antitetanus antibody titres >0.1 IU/ml and anti-Hib antibody titres >1 mg/l were regarded as protective.
  
  
  RESULTS
  Only 17% (19/111) of women exhibited a protective antibody response against pertussis. 50% (56/111) of women had levels of antibody protective against Hib and 79% (88/111) against tetanus. There was a strong positive correlation between maternal-specific and infant-specific antibodies' responses against pertussis (rs=0.71, p<0.001), Hib (rs=0.80, p<0.001), tetanus (rs=0.90, p<0.001) and pneumococcal capsular polysaccharide (rs=0.85, p<0.001). Only 30% (33/109) and 42% (46/109) of infants showed a protective antibody response to pertussis and Hib, respectively. Placental transfer (infant:mother ratio) of specific IgG to pertussis, Hib, pneumococcus and tetanus was significantly reduced from HIV-infected mothers to their HIV-exposed, uninfected infants (n=12 pairs) compared with HIV-uninfected mothers with HIV-unexposed infants (n=96 pairs) by 58% (<0.001), 61% (<0.001), 28% (p=0.034) and 32% (p=0.035), respectively.
  
  
  CONCLUSIONS
  Low baseline antibody levels against pertussis in this cohort suggest the recently implemented UK maternal pertussis immunisation programme has potential to be effective.
authors.affiliation: Academic Department of Paediatrics, Imperial College London, London, UK.
authors.forename: Christine
authors.initials: C
authors.lastname: Jones
authors.forename: Louisa
authors.initials: L
authors.lastname: Pollock
authors.forename: Sara M
authors.initials: SM
authors.lastname: Barnett
authors.forename: Anna
authors.initials: A
authors.lastname: Battersby
authors.forename: Beate
authors.initials: B
authors.lastname: Kampmann