Maternal pertussis immunization and the blunting of routine vaccine effectiveness: a meta-analysis and modeling study

Area of Science:

• Immunology
• Epidemiology
• Public Health

Background:

• Pertussis (whooping cough) control prioritizes protecting infants too young for vaccination.
• Maternal immunization has reduced infant pertussis but may cause immunological blunting, potentially affecting primary vaccine efficacy.
• Existing studies on blunting have limited follow-up and statistical power.

Approach:

• Systematic literature review of studies comparing pertussis risk in infants born to vaccinated versus unvaccinated mothers.
• Development of a novel mathematical model to simulate maternal immunization's short- and long-term effects on pertussis transmission dynamics, incorporating explicit blunting mechanisms.
• Evaluation of epidemiological evidence and modeling predictions to assess the impact of maternal immunization on infant and childhood pertussis.

Key Points:

• Meta-analysis of four studies showed a weighted mean relative risk of 0.71 (95% CI: 0.38-1.32) for pertussis after primary immunization in infants born to vaccinated mothers, indicating significant statistical uncertainty.
• Mathematical modeling suggests that transient transmission dynamics can obscure immunological blunting for up to a decade.
• Current epidemiological data may not be sufficient to exclude modest decreases in primary vaccine effectiveness.

Conclusions:

• Maternal immunization remains a critical strategy for protecting vulnerable newborns against pertussis.
• Further research and longer-term follow-up are needed to definitively assess the impact of maternal immunization on primary vaccine effectiveness.
• Despite potential blunting, current public health recommendations supporting maternal immunization are supported by predictions of continued newborn protection.