Title : Global and regional routine pertussis vaccination coverage and anti-pertussis herd immunity levels in 2024, and variation from 2019 to 2024
Abstract:
Despite the availability of pertussis vaccines since 1960, pertussis cases and outbreaks have occurred every year worldwide and pertussis resurgence has been reported in different countries in the past two decades. The pertussis prevention strategy based on routine vaccination requires achieving high percentages of coverage and high levels of pertussis vaccination effectiveness to prevent community transmission. The Immunization Agenda 2030 proposed to achieve 90% vaccination coverage for the first and third doses of DTP-containing vaccines by 2030 at the national and regional level. The study objective was to assess ten pertussis vaccination coverage and anti-pertussis herd immunity indicators globally and in World Health Organization (WHO) regions in 2024, and assess their variation from 2019 to 2024. Global and regional pertussis vaccination coverage and anti-pertussis herd immunity indicators were assessed in 2024. The three-dose DTP coverage among one-year-old children showed the percentage of one-year-old children who had completed the DTP vaccination, and the zero-dose DTP coverage among one-year-old children showed the percentage of one-year-old children who had not received any DTP dose. Based on the WHO approach, the three-dose coverage was equal to the DTP3 coverage and the zero-dose coverage was determined from 100 – DTP1 coverage. Based on a conservative approach, the three-dose coverage was determined from DTP1 x DTP2 x DTP3, and the zero-dose coverage was determined by assuming that children unvaccinated with the DTP1 vaccine could receive the DTP2 and/or the DTP3 vaccine. Means and percentages in 2024 and 2019 were compared using the t-test and Chi-square test, respectively, considering a p<0.05 as statistically significant. High-priority countries for DTP vaccination coverage increase were identified in each WHO region based on the indicators assessed in this study. In 2024, the global mean vaccination coverage for DTP1, DTP3 and three DTP doses were 90.7%, 86.6% and 72.8%, respectively. The mean three-dose DTP coverage was below 90% in all WHO regions. Anti-pertussis herd immunity levels were not sufficient for preventing Bordetella pertussis transmission in all WHO regions. Eight of the ten indicators worsened and two improved worldwide from 2019 to 2024. This study identified 27 (13.8%) high-priority countries for DTP vaccination coverage increase due to DTP1 coverage lower than 80%; 47 (24.1%) countries due to DTP3 coverage lower than 80%, and 48 (24.6%) countries due to three-dose coverage lower than 60%. Global and regional DTP vaccination coverage and anti-pertussis herd immunity indicators in 2024, although the differences between 2024 and 2019 were statistically significant only for two regional indicators.
