Epidemic thunderstorm asthma

Victorian COVID-19 Response Guidance

Emergency departments (EDs), urgent care centres (UCCs) and health services should be prepared for epidemic thunderstorm asthma (ETSA) events during the grass pollen season (1 October – 31 December).

This checklist aims to facilitate self-assessment and gap analysis of preparedness for such an event. As necessary, EDs, UCCs and health services should address any gaps in their preparedness.

Who should read this?

All clinicians who work in emergency departments (EDs) and urgent care centres (UCCs), health service staff responsible for implementing and maintaining infection control measures, health service leaders and pharmacy managers.

Managing epidemic thunderstorm asthma during the COVID-19 pandemic

During ETSA events, ED Directors and UCC Directors of Medical Services should exercise discretion around cohorting suspected COVID-19 and confirmed COVID-19 patients as well as those with asthma in order to save lives. EDs and UCCs should continue to test appropriate patients for COVID-19 where possible. For more information refer to the Department of Health information on Assessment and streaming in emergency departments and urgent care centres.

If any UCCs or EDs notice an early trend that they suspect could be indicative of an ETSA event, the numbers to call to alert the Department are the same contact details provided in the code brown planning guidance

For rural and regional health services - call your division’s emergency contact number:

• North division 1300 080 829
• East division 1300 576 518
• West division 1800 780 354
• South division 1300 528 951

For metropolitan health services - call the Department’s central emergency contact number: 1300 790 733.

About epidemic thunderstorm asthma

Epidemic thunderstorm asthma (ETSA) is the phenomenon where a large number of people develop asthma symptoms over a short period of time. It is thought to be triggered by an uncommon combination of high pollen levels and a certain type of thunderstorm.

Current understanding is that the internal contents of the grass pollen grain are released into the environment and dispersed across a large geographical area by the storm, and specifically by the wind gusts that precede these. It appears that the allergens are concentrated in these gusts, and that those people who are exposed to these winds receive a potentially large dose of the allergen. This may result in a severe response.

Unlike whole grass pollen grains, these allergens are small enough to get past the nose and throat and be breathed deeply into the lungs, where they can trigger asthma. The unique aspect of epidemic thunderstorm asthma events is the unexpectedly large and rapid surge in patient numbers resulting in significant demand on ambulance and health services, particularly emergency departments.

Those at increased risk of ETSA include people with asthma, people with a history of asthma, those with undiagnosed asthma and importantly, people with seasonal hay fever who may or may not have ever had asthma.

There is no formal or generally recognised quantitative definition of an epidemic thunderstorm asthma event and it is recognised that improved patient preparedness (for example, those with hay fever being aware of their increased risk and having knowledge of asthma first aid), improved asthma diagnosis, clinical management and self-care, and exposure avoidance are likely to diminish the health impacts from the dispersion of allergen resulting from the uncommon type of storm on a high pollen day.

The allergen in Victoria is thought to arise from rye grass pollen and therefore the outer boundaries of the risk period for this phenomenon are limited to grass pollen season.

The grass pollen season in Victoria is typically between 1 October and 31 December. In Victoria, historically epidemic thunderstorm asthma events have occurred in November and a week either side, however climate change may have an influence on this timing.

Epidemic thunderstorm asthma risk forecasts are available from 1 October to 31 December from the VicEmergency website and app. On a high-risk day and during an ETSA event the Department of Health will also issue advice and warnings on the VicEmergency warning platform.