Study Analyzes Global Pertussis Resurgence After Pandemic

A new study, published in Scientific Reports, has analyzed patterns in the resurgence of pertussis (whooping cough) following the COVID-19 pandemic. The research focused on five countries: Japan, Australia, New Zealand, China, and the United States.

Across all five countries, pertussis cases declined sharply during the pandemic (2020-2022) and then increased significantly after public health restrictions were lifted.

The analysis covered a period from 2018 to July 2025, comparing three distinct phases: pre-pandemic, pandemic restriction, and post-restriction. Researchers utilized publicly available national surveillance data to calculate incidence rates and examine demographic and geographic trends.

Key Findings by Country

Australia, New Zealand, China, and the United States all recorded their highest pertussis outbreaks in the year 2024.

Japan experienced a different pattern, with a delayed but much larger outbreak in 2025. By July 31, 2025, Japan had reported 60,826 cases—a figure more than ten times higher than its total for the entire year of 2024.

Demographic Shift in Japan's Outbreak

During Japan's 2025 outbreak, a notable shift in affected age groups was observed.

Individuals aged 10 to 19 accounted for more than 50% of all cases, with an incidence rate exceeding 270 per 100,000 population.

Vaccination Context and Study Limitations

The study noted that vaccination coverage for primary childhood immunization remained high across all five countries. However, strategies and schedules for booster vaccinations varied between nations.

The authors were careful to state the descriptive nature of their work. They clarified that the study could not prove a single cause for the global resurgence or directly link differences in booster policies to the specific timing and size of the observed outbreaks.

Implications and Conclusions

The researchers suggested their findings raise important questions about waning immunity over time and the role of booster vaccination strategies.

The shift in cases toward older children and teenagers has clear implications for transmission dynamics and for protecting the most vulnerable population: infants.

The study concluded by stating that the findings support considering routine booster vaccines and vaccination during pregnancy as potential public health strategies. However, they emphasized this does not prove that these measures alone will prevent future outbreaks.