Coronavirus-recovered patients are being warned they are at higher risk of suffering from thunderstorm asthma.
It comes as new research has revealed a “trifecta of risk” with people most likely to suffer from thunderstorm asthma having three things in common: rye-grass pollen allergy, undiagnosed asthma and no action plan for treatment.
Severe storms and heavy rainfall are set to bring an elevated risk of an allergic asthma event across Victoria on Wednesday.
A high to moderate risk of epidemic thunderstorm asthma has been forecast for western and central Victoria on Wednesday as an extreme pollen count combines with potentially severe thunderstorms and strong winds.
Ten people died when Melbourne experienced the world’s largest epidemic thunderstorm asthma event on November 21, 2016.
In the 30 hours from 6pm on that date, there was a 672 per cent increase in respiratory-related presentations to Melbourne and Geelong public hospitals, while triple-0 call outs also spiked.
Associate Professor Cenk Suphioglu from Deakin University’s NeuroAllergy Research Laboratory said people most at risk of thunderstorm asthma had an existing grass pollen sensitivity, especially to rye-grass pollen, but might not be aware they had undiagnosed asthma.
He said a further high-risk group included those who had suffered from COVID-19 during this year’s pandemic.
Victoria has 19,522 people who have recovered from coronavirus.
“Any infection that impacts on our airways is going to make us vulnerable, and this includes COVID-recovered patients, especially since their respiratory infection and treatment may have also compromised their immune system,” Dr Suphioglu said.
He said people of Asian ethnicity were also more susceptible to thunderstorm asthma, which is believed to be because allergic rhinitis is twice as common in this population compared with non-Asians.
Dr Suphioglu said all seven previous thunderstorm asthma epidemics in Melbourne – in 1984, 1987, 1989, 2003, 2010, 2011 and 2016 – had occurred in November when rye-grass pollination was at its peak.
His research into the 2016 event found all patients hospitalised in 2016 suffered from rye-grass pollen sensitisation.
“The second risk factor we identified was people with no previous history of asthma or undiagnosed asthma, that is, people with a predisposition to asthma but who have never had an asthma attack that led to an official diagnosis,” he said.
“This leads into the third factor, which is having no asthma action plan or medication to treat asthma.
“The second and third factors are particularly worrying because it is estimated that between 20 to 70 per cent of people with asthma are undiagnosed and not receiving treatment.”
During a thunderstorm asthma event, rye-grass pollen is sucked up into the clouds where they rupture, releasing tiny highly allergenic particles, which have the ability to penetrate deep within the lungs.
The subsequent strong downdrafts dump these particles onto the ground and they are swept over long distances by strong outflows, travelling from regional farming areas into towns and cities.
Dr Suphioglu said he was expecting a bad season for thunderstorm asthma this year, as Melbourne’s wet winter and spring had created a big grass reservoir.