23 June 2026 

Cambridge researchers, supported by NIHR Cambridge BRC, have shown that severe pneumonia has three different subtypes, helping explain why some patients in intensive care units (ICUs) recover from their illness faster than others, while for other patients the disease can be life-threatening.

Their findings could in future help inform tailored treatments, allowing individual patients to receive the most appropriate therapies.

Pneumonia is the commonest infectious cause of death worldwide, responsible for an estimated 2.5 million deaths per year. In severe cases, patients may need to be admitted to an ICU and given mechanical ventilation. Severe pneumonia accounts for six in 10 infections managed in intensive care, and spread of the infection within ICUs is a significant concern.

Doctors have long struggled to understand why patients whose condition looks similar clinically can have very different recoveries. Some respond quickly to treatment, while others remain critically ill for weeks or even die.

Dr Andrew Conway Morris from the Department of Medicine at the University of Cambridge and an ICU consultation at Addenbrooke’s Hospital, Cambridge, said: “Even though we’re able to treat the initial infection, many patients with severe pneumonia still struggle to come off the ventilator and can develop lung failure. Therapies to tackle inflammation in the lungs have had mixed results in clinical trials – some suggest they are beneficial, others that they’re harmful.

“The current approach of classifying patients by their clinical syndromes – sepsis, acute respiratory distress syndrome and so on – without looking at the underlying biology risks missing what’s key. Instead of asking ‘Does this patient have pneumonia?’, we should be asking ‘What’s the inflammatory pattern in this patient’s lungs?’”