Asthmatics less likely to catch coronavirus, study suggests

Woman with asthma using an inhaler for relief.
People with asthma may be less likely to catch the coronavirus, research suggests. (Posed by a model, Getty Images)

People with asthma may be less likely to catch the coronavirus, research suggests.

With asthma a respiratory condition and the coronavirus infecting the airways, experts flagged early in the pandemic those with the breathing disorder may endure more serious viral complications.

One in 12 adults in the UK has asthma, with the severity of the condition varying significantly between patients.

Most with the breathing disorder are considered at moderate risk and therefore “clinically vulnerable”. In severe cases, the risk becomes high and the patient “extremely clinically vulnerable”.

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A study of more than 37,000 people by Tel-Aviv University has since revealed, however, people with asthma may be less likely to catch the infection in the first place.

Although unclear exactly why this may occur, “respiratory allergy is associated with significant reductions in ACE2 receptors” – the entry point for the coronavirus into cells, according to the scientists.

Portrait of young African businessman with mask for protection from corona virus outbreak at the sky train station
It has been suggested people with asthma may adhere more strictly to rules around face coverings. (Posed by a model, Getty Images)

With asthma being a common but sometimes serious condition, the scientists felt the coronavirus risk among people with the breathing disorder had “not been adequately assessed”.

Previous studies suggest 9% of hospitalised coronavirus patients in New York and 14% in the UK have asthma.

The Tel-Aviv scientists pointed out, however, these were inpatients, not those carrying a relatively mild infection in the community.

To learn more, the team analysed 37,469 people who took part in a “large nationwide health maintenance organisation” in Israel between February and June, all of whom had been tested for the coronavirus.

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Results, published in The Journal of Allergy and Clinical Immunology: In Practice, revealed that 153 (6.75%) of those who swabbed positive for the infection had asthma.

Among those who tested negative for the coronavirus, 3,388 (9.62%) had asthma – a 35% difference.

The use of anti-asthma drugs, like inhaled corticosteroids, was not found to influence the risk of infection.

Taking into account other factors that may contribute to a person catching the coronavirus – like age, smoking status and underlying health conditions – the scientists concluded “a negative association of asthma with the likelihood of being positive for COVID-19 [the disease caused by the coronavirus]”.

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With previous research suggesting people with asthma have fewer ACE2 receptors in their lungs, the coronavirus may therefore have less entry points in the bodies of these patients.

The circulating coronavirus is said to be more than 80% genetically identical to Severe acute respiratory syndrome (Sars), which killed 774 people during its 2002/3 outbreak.

With Sars also entering cells via ACE2 receptors, fewer people with asthma were said to have caught the infection nearly two decades ago.

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Other viruses of the same class – like Middle East respiratory syndrome (Mers) – however, do not use ACE2 and are said to make asthma more severe.

Alternatively, people with asthma may be more conscious of the coronavirus and its complications, prompting them to adhere more strictly to face coverings, hand washing and social distancing.

The scientists stressed further research is required. In the meantime, doctors should continue to treat asthma as normal, they added.

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