Immune interference (blunting) in the context of maternal immunization with Tdap-containing vaccines: is it a class effect?

Plain Language Summary What Is the Context? Pertussis, also known as whooping cough, is a highly infectious respiratory disease. Although it can affect all ages, the number of complications and deaths from infection are highest in infants who are too young to mount protective antibody responses after vaccination (<2-3 months). Immunizing pregnant women with tetanus-diphtheria-acellular pertussis (Tdap) vaccine protects children against pertussis in early infancy . Antibodies are transferred from the mothers to the fetus through the placenta and infants are protected before they receive their primary vaccination of a pertussis-containing vaccine. The presence of maternal antibodies may interfere with the infant immune response to routine pertussis combination vaccines in early life. It can lead to a lower responsiveness of infants whose mothers have been vaccinated. This immunological interference is called blunting. What is new? We reviewed the available data in the published literature on blunting following maternal immunization with pertussis containing combination vaccines. We found that: The blunting of the infant response The impact on children's health of blunting for pertussis remains unknown. However, there has been no increase in pertussis disease in countries with a universal maternal immunization program Despite this success, pneumococcal diseases still pose an important health issue and efforts are needed to tackle this. What is the impact? Surveillance of pertussis epidemiology in various settings using different combinations of maternal and pediatric vaccines is needed to assess the clinical impact of blunting Introduction: Maternal immunization with reduced antigen content tetanus-diphtheria-acellular pertussis (Tdap)-containing vaccines has been recommended to prevent infant pertussis. However, maternal antibodies may interfere with infant responses to routine immunization with diphtheria-tetanus-acellular pertussis (DTaP)-containing vaccines, raising concerns of suboptimal protection after infant vaccination. We performed a narrative literature review to assess whether blunting occurs regardless of the manufacturer of maternal and infant vaccines. Because internationally agreed correlates of protection are lacking, the clinical significance of blunting is not yet fully understood. We have reviewed the evidence available to date. Areas Covered: Thirteen studies that evaluated blunting after maternal immunization and infant primary/booster series were identified. Blunting was observed with various combinations of Tdap- and DTaP-containing vaccines for maternal and pediatric immunization. Studies assessing the effectiveness of maternal Tdap immunization beyond the primary infant immunization series in England and in the United States suggested no evidence of a clinically relevant blunting effect so far. Expert commentary: This review indicates that the phenomenon of blunting does not depend on the manufacturer/brand of the pertussis-containing vaccines used for immunizing mothers or children. Currently, there is no epidemiological evidence that children whose mothers received Tdap are at increased risk of pertussis after pediatric vaccinations, although longer follow-up is required.