Understanding the transmission of COVID-9 via aerosols in healthcare
Aerosols are tiny droplets suspended in the air which can carry viruses such as the one that causes COVID-19. They are a very common way for respiratory infections to be transmitted. Aerosols were thought to be generated during many medical procedures (aerosol generating procedures or AGPs). However the actual risk of generating aerosols during these procedures was largely unknown at the start of the pandemic. This uncertainty led to rapidly issued guidance, including for all NHS staff involved in AGPs to wear enhanced respiratory personal protective equipment. These precautions led to delays in care, despite being based on little evidence. Research on AGPs was urgently needed to ensure precautions were only used when necessary, allowing the NHS to protect patients and staff whilst resuming life-saving work.
What translational research was done?
We collaborated with leading aerosol scientists at the Bristol Aerosol Research Centre on AERATOR. It received UKRI-NIHR funding and was the only experimental science Urgent Public Health study.
AERATOR looked at potential AGPs (Aerosol Generating Procedures) across NHS and dental services. We were first in the world to design and deliver high quality experimental studies measuring aerosol generation from healthy volunteers and patients, using state-of-the-art techniques.
We were the first group to record aerosol measurements from COVID-19 patients. We remain the only group to have recorded aerosol emission from lung function testing, oxygen delivery, and non-invasive ventilation in an ultra-clean, near-zero aerosol background.
We showed that most AGPs listed by the Scientific Advisory Group for Emergencies (SAGE) don’t generate aerosols. They were much more likely to occur in normal breathing, speaking and coughing than during medical procedures.
Translation into later phase research, clinical practice and patient benefit
Our AERATOR collaboration has pioneered the translation of aerosol sciences into the clinical environment. Our results informed vital policy changes. They were communicated to the NIHR Task and Finish Group, feeding directly to SAGE. NHS England’s list of AGPs was updated based on our work. Our findings on the dangers of coughing to healthcare workers were covered on the front page of The Guardian.
Guideline development groups including the Royal College of Anaesthetists, British Thoracic and Primary Care Respiratory Societies and Scottish Dental Clinical Effectiveness Programme used AERATOR data to revise guidance, allowing NHS services to safely start up again.
References
1. Brown et al., Anaesthesia, 2020;DOI:10.1111/anae.15292
2. Shrimpton et al., Anaesthesia, 2021;DOI:10.1111/anae.15542
3. Arnold et al., Eur Respir J;2021;DOI:10.1183/13993003.01064-2021