Background As COVID-19 cases continue to decline, other respiratory pathogens, including Mycoplasma pneumoniae, may become more prevalent. Surveillance helps healthcare providers distinguish between different respiratory infections, crucial for appropriate treatment and management. Given the rise in the incidence of M. pneumoniae in the current winter respiratory season, a seasonal review was carried out comparing the numbers reported by different surveillance programmes set up by Public Health Scotland (PHS), within the primary and secondary care settings.

Methods Analysis was carried out on routine PHS based surveillance systems. This included laboratory confirmed cases from all over Scotland, where M. pneumoniae is tested as part of clinical care, and emergency hospital admissions with a positive M. pneumoniae test within 14 days pre/two days post admission date, over the last seven years. We also looked at the M. pneumoniae swab positivity for the current season 2023/24 in the Community Acute Respiratory Infection (CARI) surveillance programme, comprising of sentinel practices, collecting samples from patients who present with symptoms of acute respiratory infection (ARI).

Results M. pneumoniae has been circulating at pre-pandemic levels with a continuous rise in cases from November 2023 onwards. This was seen among the laboratory confirmed cases, as well as M. pneumoniae related hospital admissions. Although the past six years showed a low and stable picture, similar peaks were seen in season 2016-17. However, the current reporting period has witnessed a surge in case numbers surpassing the highest recorded figures observed during the 2016-17 season. Notably, minimal instances were reported during the years of the pandemic. The demographic most significantly affected was the school-age population. The CARI programme showed a parallel trend, with M. pneumoniae swab positivity steadily rising from late October 2023 onwards, peaking in January 2024. Notably, there was a significant increase in swab positivity among individuals aged 5-14 years.

Conclusion The 2023-24 season witnessed a significant surge in M. pneumoniae cases, surpassing previous peak figures from 2016-2017, particularly affecting the school-age population. Several factors contribute to this increase, including inadvertent reduction in exposure during the pandemic, behavioural changes upon lifting restrictions, genetic variability leading to new strains, improved diagnostics, and interactions with other respiratory pathogens. Ongoing surveillance efforts beyond COVID-19 are crucial for detecting and managing respiratory pathogens effectively. Collaboration between healthcare providers and public health agencies is vital to mitigate the impact of M. pneumoniae outbreaks, emphasizing the importance of robust public health measures and antibiotic stewardship to safeguard public health and prevent further transmission.