An estimated 18.9 million people worldwide developed pertussis (whooping cough), and 115,000 died from the disease in 2023, with infants and people in sub-Saharan Africa bearing a disproportionate burden, according to a study published last week in Nature Medicine.
“This burden remains profoundly inequitable and inversely correlated with the sociodemographic index,” write the researchers, who were led by a team at the Institute for Health Metrics and Evaluation at the University of Washington in Seattle. “Sub-Saharan Africa now accounts for roughly 65% of global deaths, with the highest population-adjusted risk concentrated among infants younger than 6 months.”
Pertussis remains a major cause of vaccine-preventable mortality, despite long-standing immunization programs.
Cases, deaths rose sharply after pandemic
To estimate pertussis incidence, mortality, and disability-adjusted life years across 204 countries and territories, the team analyzed data from the Global Burden of Disease 2023 study.
The investigators found that, from 1990 through 2023, age-standardized pertussis incidence declined by 41.6%, and the age-standardized death rate fell 61.2%.
This burden remains profoundly inequitable and inversely correlated with the sociodemographic index.
But cases and deaths rose sharply after the COVID-19 pandemic. Compared with 2020 estimates, pertussis incidence rose by 102.6%, and pertussis-related mortality increased 66.1% by 2023 (though the 95% uncertainty intervals [UIs] were wide—77.0% to 128.2% and 2.4% to 174.5%, respectively—indicating considerable imprecision in the numbers).
Those increases largely represented a return to pre-pandemic levels, however, rather than an unprecedented global surge, with the estimated age-standardized incidence rate in 2023 being broadly comparable to the 2019 rate.
Deaths concentrated in sub-Saharan Africa
Sub-Saharan Africa accounted for roughly 65% of estimated pertussis deaths in 2023, up from approximately 30% in 1990. “This growing proportional share primarily reflects slower rates of decline compared to other regions, rather than an absolute increase in regional mortality,” write the researchers.
Infants younger than 6 months had the highest risk of death globally, at 45.7 per 100,000 (although the UI was wide)—more than double that of the 12- to 23-month-old group (19.6) and nearly triple that of the 2- to 4-year-old group (6.6). “This intense risk concentration in early infancy represents a marked improvement from 1990, when mortality rates in the 1–5-month group were 108.1 per 100,000,” note the researchers.
Improvement in infant mortality was slowest in sub-Saharan Africa: While the mortality rate among infants had declined by 58.1% since 1990, it remained remarkably high, at 92.1 per 100,000, but again with wide UIs, in 2023.
The authors call for stronger routine immunization and access to care in regions where pertussis deaths are highest, along with continued surveillance to detect and prevent transmission. They also emphasize timely infant and maternal immunization to protect babies before they complete their primary vaccine series.
