Investigation of immunity against Bordetella pertussis in pregnant women and an overview of the vaccination schedule in Turkey

Pertussis caused by Bordetella pertussis, is a disease leading to significant morbidity and mortality in neonates and infants. Direct protection of the infant may be achieved by maternal and neonatal vaccination. Despite primary vaccination, infants under six months pose the greatest risk of infection with pertussis. Maternal immunization provides a high level of infant protection from birth until immunity is achieved by active vaccination. There is no routine Tdap vaccination recommendation for pregnant women in Turkey. This study was carried out to determine pertussis antibody levels in pregnant women and provide data for improving vaccine planning. The study was carried out with 133 pregnant women in Turkey. Antibody titers to pertussis toxin (anti-PT) and filamentous hemagglutinin (anti-FHA) were measured by the commercially available ELISA. Among 133 participants, 93 (69.9%) were found to be immune according to anti-PT IgG antibody levels. According to anti-FHA IgG antibody levels, 123 (92.5%) participants were considered to be immune. A positive correlation was observed between PT and FHA and the findings were statistically significant (P < 0.001, r = 0.343). In the study group, the ages of the participants varied between 17 and 44 years. The mean age of those who were immune was 27.3±5.6, the mean age of non-immune patients was 29.1±6.2 and the difference was not statistically significant (P= 0.14). Our results reveal that approximately one-third of pregnant women were not immune to pertussis, reflecting many young infants to be vulnerable to pertussis infection until the onset of primary vaccinations, although childhood pertussis vaccination coverage has been high for a long time. We conclude that Tdap vaccine recommendation for pregnant women regardless of previous immunization history may be beneficial for the protection of infants in their first six months.