A pneumonia-causing bug disappeared during the pandemic – but a surge may come this winter

• There were record numbers of people infected with respiratory syncytial virus (RSV), flu and even strep A.
• But the latest data suggests a surge in infections may be coming this winter.
• It typically causes a mild chest infection, but it can cause life-threatening illness, such as pneumonia and brain swelling.
• As with other respiratory infections, M pneumoniae is transmitted when an infected person coughs or sneezes, creating “respiratory droplets”.
• Crowded places, such as schools and hospitals, are ideal environments for the bug to spread.

Potential resurgence

• But, contradicting these trends, between April 2021 and March 2022 – when most other respiratory infections had made a comeback- – M pneumoniae infections remained largely absent.
• Data from 212,207 diagnostic tests collected from 42 sites across 23 countries identified only 214 samples positive for M pneumoniae (0.1% of the samples).
• The reasons for this lack of resurgence are not fully understood and are probably due to many factors.
• M pneumoniae infections are known to peak and trough, with epidemics occurring every four to six years as alternative variants circulate.