The impact of multiplex panel testing on ascertainment of pertussis-attributable deaths: national surveillance from England

Understanding the burden of pertussis and pertussis-related mortality is important in enabling better understanding of population vulnerability and supporting vaccination programme planning. However, changes in laboratory practice can have important implications for public health surveillance. This study considers the impact of increasing use of multiplex panel testing for respiratory pathogens on ascertainment of pertussis-related deaths, drawing on multiple surveillance data sources from England. Information was sourced from Office of National Statistics cause of death records, public health case management records, laboratory results collated nationally, and death notifications received via General Practices. Figures covered the period 2023/24, coinciding with a large, national outbreak in England, and were compared with data from 2012 - the last major outbreak in England. Of 34 deaths identified among individuals aged >12 months in 2023/24, 11 ultimately met pre-defined criteria to be classified as pertussis-related deaths; none of the 5 possible cases identified in 2012 did so. A total of 25 of the 34 (74%) tested positive for pertussis via multiplex panel testing, of which 18 (72%) were ultimately excluded as pertussis-related deaths. Findings highlight significant challenges in attribution of pertussis-related mortality in an era of widespread multiplex panel testing.