Research interests include respiratory infection, specifically pleural infection, COVID-19 and pneumonia, and malignant pleural disease including mesothelioma. His PhD, funded by the NIHR Doctoral Research Fellowship programme, focused on novel management of pleural infection to reduce the burden on patients and the health system.​ He has recently been awarded an NIHR Advanced Fellowship in clinical trials. He has a total grant income of over £5.5million as principal investigator and over 70 peer reviewed publications (h-index > 30).

At the start of the COVID-19 pandemic David co-led a multicentre observational study of patients admitted with COVID-19 (DISCOVER study), the results of which have contributed to national guidance. He was also part of the AERATOR study team, funded by an NIHR Rapid COVID call, a cross-collaborative project assessing aerosol emission from medical procedures.​
He leads several trials in respiratory infection including the the ASPECT trial, a large randomised trial of aspirin to reduce cardiovascular events following pneumonia, and the IMPACT trial, a randomised trial of different management strategies for pleural infection.