A Trial Comparing Two Pertussis-containing Vaccines in Pregnancy and Vaccine Responses in UK Mothers and Their Infants

A Randomised Controlled Trial Comparing Two Pertussis-containing Vaccines in Pregnancy and Vaccine Responses in UK Mothers and Their Infants

Due to an unexpectedly high number of infant deaths from whooping cough in 2012, the Department of Health acted to protect newborns between birth and completion of primary immunisations, the period with greatest risk of disease.

Vaccination of pregnant women with whooping cough vaccine in the third trimester of pregnancy was instigated nationally, so that antibodies produced by the Mum would cross the placenta to the unborn child, giving them passive protection at the most vulnerable time. This antibody transfer has been known for some time but has not been compared between the two whooping cough vaccines being used in pregnancy. Any effect the raised antibody might have on infant responses to the vaccines given in the first few months of life has also not been measured. This is particularly important as the infant immunisations include some of the same components as the whooping cough vaccines, which include diphtheria, tetanus and polio. Previous studies have shown that high levels of antibody prior to vaccination may affect subsequent antibody responses. It is therefore important to assess whether administration of the whooping cough vaccine in pregnancy adversely affects the protection afforded by the infant vaccines, particularly to those which are similar, namely tetanus and diphtheria as well as meningitis C and Hib vaccines which include diptheria and tetanus components in their structures. This study will assess immune responses of mothers and their babies (~200 pairs) to their vaccinations and will allow the comparison of two whooping cough vaccines being used in pregnancy. This will be done by taking small amounts of blood, which is the only way to measure antibody levels (the proxy of the immune response), before and after the vaccinations. A group of unvaccinated women and their babies (50 pairs) will also be recruited to allow comparison of their immune responses.

Inclusion Criteria:

Pregnant women who, at the time of enrolment

• are aged 1645 years Infants of the women recruited will also be seen during the study. They will be given their immunisations according to the routine childhood immunisation schedule and will have blood samples collected as detailed in the clinical procedures section of this form. Their inclusion/ exclusion will be as per the Green Book recommendations by the UK Dept of Health.

Exclusion Criteria:

Participants may not be included in the study if any of the following apply:

All women:

• Bleeding disorder
• Receipt of any pertussis containing vaccine in the previous 12 months

Women to be vaccinated only (i.e. not the control group):

• Received immunoglobulin or other blood product within the preceding 3 months

• Fulfil any of the contraindications to vaccination specified in The Green Book on Immunisation (https://www.gov.uk/government/organisations/publichealthenglan d/series/immunisationagainstinfectiousdiseasethegreenbook), including:

  • A confirmed anaphylactic reaction to a previous dose of diphtheria, tetanus, pertussis or poliomyelitis containing vaccine
  • A confirmed anaphylactic reaction to any component of the vaccine
  • A confirmed anaphylactic reaction to a previous dose of diphtheria, tetanus, pertussis or poliomyelitis containing vaccine
  • Temporary Exclusion Criteria If the pregnant woman or the baby has an axillary/aural temperature ≥ 38°C, then vaccination and blood sampling will be postponed until resolution of fever. If the pregnant woman or baby is acutely unwell, vaccination will postponed until resolution. Blood sampling will also be postponed for seven days after completion of any antibiotic course.

Infants will be vaccinated under the routine national immunisation schedule in accordance with the inclusion/ exclusion criteria set out in the Department of Health "Green Book"