Maternal vaccination: shaping the neonatal response to pertussis

Abstract

Antepartum maternal vaccination can protect highly sensitive newborns before they are old enough to receive their own vaccines. Two vaccines are currently recommended during pregnancy: the flu vaccine and the Tdap vaccine against tetanus, diphtheria, and pertussis. Although there is strong evidence that maternal vaccination works to protect the offspring, limitations in the understanding of vaccines and of maternal transfer of immunity compound to obscure our understanding of how they work. Here we focus on the example of pertussis to explore the possible mechanisms involved in the transfer of protection to offspring and how these may impact the newborn's response to future exposure to pertussis. For example, Tdap vaccines induce pathogen specific antibodies, and those antibodies are known to be transferred from mother to the fetus in utero and to the newborn via milk. But antibodies alone have modest impact on pertussis disease, and even less effect on colonization/transmission. Maternal immune cells can also be transferred to offspring and may play a direct role in protection from disease and/or influence the developing neonatal immune system. However, some of the transferred immunity may also blunt the offspring's response to subsequent vaccination. In this review we will summarize the protection conferred to offspring by maternal vaccination against pertussis and the likely mechanisms by which protection is transferred, identifying the many knowledge gaps that limit our most effective application of this approach.

Keywords: DTaP; Tdap; maternal vaccination; neonatal immunity; pertussis; vaccines; window of opportunity.

Figure 1

The timeline of recommendations from the Advisory Committee on Immunization Practices for administering the Tdap vaccine for Pregnant Women and Close Families. Created with Biorender.com.

Figure 2

Main components of the two pathways of maternal immune component transfer. (A) Immune components are transferred from the blood of the mother through the placenta to the fetus. (B) The transfer of immune components through the breast milk occurs through the mammary gland epithelia to the lumen containing breast milk. Created with Biorender.com.

Figure 3

The blunting effect of maternal antibodies on the development of DTaP antibody responses by the offspring following vaccination. (A) represents the normal antibody response to vaccines. Each booster induces higher concentrations of anti-Bp antibodies. (B) Represents the offspring’s antibody response in the presence of Maternal antibodies. Here the response is delayed until the Maternal antibodies’ levels have depleted. Created with Biorender.com.