Unusual surge in children’s pneumonia cases in England linked to Mycoplasma pneumoniae

In a recent study published in the journal Eurosurveillance, researchers investigated the unusual rise in emergency department (ED) visits for pneumonia among children aged 5–14 years in England since November 2023.

Their findings indicate that this increase, which persisted into early summer 2024, was primarily driven by the bacteria Mycoplasma pneumoniae (MP), even as other seasonal respiratory infections decreased.

Background

Respiratory infections during the winter often burden healthcare services in the UK. The UK Health Security Agency (UKHSA) manages a surveillance program that tracks and reports respiratory illnesses yearly to help understand and manage their impact.

Recently, an unusual rise in pneumonia cases among children between the ages of 5 and 14 was detected through the program, leading to an investigation to understand what was causing this unexpected increase.

About the study

The UKHSA’s program monitors respiratory infections through various systems, including lab reports, general practice data, and real-time tracking of ED visits.

The surveillance program includes data from primary care physicians, laboratory reports, hospital admissions, ED attendance, and telehealth calls, monitoring a range of respiratory indicators from the milder common colds, which are self-limiting, to more severe illnesses like pneumonia.

This monitoring helps identify mild and severe respiratory illnesses and their effects on the healthcare system, particularly during the high-demand winter months.

Findings

Beginning in November 2023, the number of children between the ages of 5 and 14 visiting EDs for pneumonia began to rise above historical expectations, as observed through the UKHSA’s syndromic surveillance system.

This elevated activity continued through December 2023 and did not follow the typical seasonal decline in January 2024. Instead, the higher-than-expected number of pneumonia-related ED visits persisted between February and July 2024.

During this period, 2,532 pneumonia-related ED visits were recorded in this age group, which, while lower than the 45,003 cases reported in individuals aged 15 years and older, was still significantly higher than in previous years.

For context, the average number of visits during the same period of 2019-20 and 2022-23 for this age group were, respectively, 607 and 818, highlighting a notable surge in 2024.

Further analysis using data from the Emergency Care Dataset (ECDS) and linked laboratory reports confirmed that, between November 2022 and May 2024, there were 14,096 pneumonia-related ED attendances, with 2,334 of these linked to positive microbiology results.

Among the pathogens identified, Respiratory Syncytial Virus (RSV) accounted for 16.6% of cases, influenza A virus for 9.8%, and MP for 9.3%.

While RSV and influenza followed their usual seasonal patterns, MP showed a marked increase in early 2024, particularly among children aged 5–14, where it was found in 32.2% of pneumonia cases.

Additionally, increasing trends in MP infections were observed in children between the ages of 1 and 4, suggesting a broader impact across younger age groups.

Conclusions

The study found a persistent increase in emergency department visits for pneumonia among children between the ages of 5 and 14, primarily due to an unusual rise in MP infections during the winter of 2023-24, the first significant MP epidemic after the coronavirus disease 2019 (COVID-19) pandemic.

MP is a common cause of bacterial pneumonia among school-going children, and while infections are usually mild, some can lead to severe illness.

The study highlights the importance of real-time syndromic surveillance, which enabled early detection of this trend and timely public health responses. England’s 2023-24 MP epidemic was part of a global increase in MP cases, but the unusually prolonged season was notable.

The reasons for this prolonged activity remain unclear, but it might be linked to changes in disease transmission patterns due to pandemic-related public health measures.

In conclusion, the study underscores the value of the UK Health Security Agency’s (UKHSA) comprehensive respiratory surveillance program, which includes real-time syndromic surveillance to detect and quickly investigate unusual patterns of illness.

The findings also indicate the need for further research to better understand MP and its impact on public health.