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Decreased chlamydia notifications in six European Union/European Economic Area countries and England, 2024
Ana Martina Astorga Alsina1, Joana Gomes Dias1, Cornelia Adlhoch1
1European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden.
Summary
Chlamydia notifications declined in several European countries between 2023 and 2024, particularly among young people. Reduced testing and lower positivity rates were observed, though further investigation is needed.
Area of Science:
- Public Health
- Epidemiology
- Infectious Diseases
Background:
- Bacterial sexually transmitted infection notifications have risen across the European Union/European Economic Area (EU/EEA) and England over the past decade.
- Despite the general trend, several EU/EEA countries and England reported decreases in chlamydia notifications from 2023 to 2024.
Purpose of the Study:
- To investigate the drivers behind the reported declines in chlamydia notifications in specific EU/EEA countries and England.
- To analyze national surveillance data and contextualize findings with testing practices, policies, and public health interventions.
Main Methods:
- Analysis of national surveillance data from 2015 to 2024 for seven EU/EEA countries and England.
- Comparison of 2024 chlamydia notifications with expected counts based on pre-COVID-19 pandemic trends (2015-2019) using a negative binomial model.
Main Results:
- Chlamydia notifications decreased by 13% to 19% between 2023 and 2024, primarily impacting individuals aged 15-24 years.
- Five countries reported reduced testing volumes among young people, and all observed lower positivity rates.
- Case numbers fell below the 95% prediction interval in three countries.
Conclusions:
- Observed declines in chlamydia notifications may be linked to reduced testing, behavioral changes during the COVID-19 pandemic, and shifts in the risk profile of individuals seeking testing.
- Further investigation is required to fully understand the underlying drivers and inform effective sexual health strategies in Europe.
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