What is the true burden of diphtheria, tetanus, pertussis and poliovirus in children aged 3–18 years in Asia? A systematic literature review.

In recent years, outbreaks and a rising incidence of diphtheria, tetanus, and pertussis have occurred in Asia, particularly in older children. A systematic search of MEDLINE and Embase was conducted from January 2000 to October 2020 to identify the epidemiology of diphtheria, tetanus, pertussis, and poliomyelitis in children and adolescents (aged 3–18 years) in Asia. The results were then related to vaccination schedules, booster coverage rates, pertussis source of infection, and booster immunogenicity, as identified by a pragmatic review. The International Prospective Register of Systematic Reviews (PROSPERO) registration: #CRD42020222445. A total of 35 studies were included in this review. Limited data were reported on the epidemiology of diphtheria, tetanus, pertussis, and poliomyelitis. Data from studies reporting the incidence of diphtheria and pertussis exemplify the shift in epidemiology to older children/adolescents. Seroprevalence data suggest that immunity to pertussis and diphtheria is below the level of herd immunity in several Asian countries in this population. The true burden of diphtheria, pertussis, and tetanus in children aged 3-18 years in Asia is unknown because of weak or absent nationwide surveillance systems. The available evidence highlights the inadequacies in immunity, either by gaps in a recommendation or suboptimal booster coverage, supporting the public health need for booster vaccinations in this population.