Unusual rise in childhood pneumonia cases in England linked to Mycoplasma pneumoniae

In a recent study published in the journal EurosupervisionResearchers investigated an unusual raise in emergency department (ED) visits due to pneumonia among children aged five to 14 in England from November 2023.

Their findings indicate that the raise, which continued into early summer 2024, was primarily caused by bacteria Mycoplasma pneumoniae (MP), although other seasonal respiratory infections decreased.

Speedy communication: Childhood pneumonia cases in England continue to rise, 2023/24. Photo source: Kateryna Kon / Shutterstock

Background

Respiratory infections in winter are a common burden on UK health services. The UK Health Security Agency (UKHSA) manages a surveillance programme that tracks and reports respiratory illnesses each year to support understand and manage their impact.

Recently, the program observed an unusually high raise in pneumonia cases among children aged 5 to 14, prompting an investigation to determine the cause of the unexpected raise.

About the study

The UKHSA programme monitors respiratory infections using a variety of systems including laboratory reporting, general practice data and real-time tracking of emergency department visits.

The surveillance program combines data from primary care physicians, laboratory results, hospital admissions, emergency department visits and telemedicine calls, monitoring a range of respiratory indicators, from soft colds that go away on their own to more grave illnesses such as pneumonia.

This monitoring helps identify soft and severe respiratory illnesses and their impact on the healthcare system, especially during the winter months when demand is highest.

Results

Since November 2023, the number of children aged 5 to 14 years presenting to emergency departments with pneumonia has increased above historical expectations, as seen in the UKHSA clinical signs surveillance system.

This increased activity continued into December 2023 and was not followed by the typical seasonal decline in January 2024. Instead, higher-than-expected numbers of pneumonia-related ED visits continued from February to July 2024.

During that time, there were 2,532 emergency department visits for pneumonia among that age group. While that number is lower than the 45,003 cases reported in people aged 15 and older, it is still significantly higher than in previous years.

In comparison, the average number of visits during the same periods in 2019-20 and 2022-2023 for this age group was 607 and 818, respectively, indicating a significant raise in 2024.

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

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

While RSV and influenza followed their usual seasonal patterns, MP saw a marked raise in early 2024, particularly among children aged 5 to 14 years, who were found in 32.2% of pneumonia cases.

Furthermore, an increasing trend of MP infections was observed in children aged 1 to 4 years, indicating a broader impact on younger age groups.

Conclusions

The study found a steady raise in emergency department visits due to pneumonia among children aged 5 to 14 years, largely due to an atypical raise in MP infections during the winter of 2023–2024, the first significant MP epidemic following the coronavirus disease 2019 (COVID-19) pandemic.

MP is a common cause of bacterial pneumonia in school-age children. Although infections are usually soft, some can lead to severe disease.

The study highlights the importance of real-time syndromic surveillance, which enabled early detection of this trend and rapid public health response. The 2023–24 MP epidemic in England was part of a global raise in MP cases, but the unusually prolonged season was noteworthy.

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

In summary, the study highlights the value of a comprehensive respiratory surveillance programme run by the UK Health Security Agency (UKHSA), which includes ongoing surveillance of disease syndromes to detect and rapidly investigate unusual patterns of disease.

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