- Researchers say people with allergies and type 2 asthma may have a lower risk of developing COVID-19.
- They say the resistance may be due to the fact that allergic inflammation in the airways may suppress the effectiveness of a receptor used by SARS-CoV-2.
- Experts say people with allergies and asthma should still get vaccinated, as well as practice safety measures such as mask wearing and physical distancing.
Could people with certain kinds of allergies and asthma be more resistant to COVID-19?
A study from the Queen Mary University in London looking at COVID-19 impacts across society hints at the possibility.
Researchers used monthly questionnaires with more than 15,000 study participants to look at all kinds of possible COVID-19 health interactions such as sex, age, comorbidities, workplaces, and lifestyle habits.
While the study was not created to look specifically at allergies and asthma, researchers said the data around those conditions jumped out at them.
Adrian Martineau, PhD, a lead study author and a professor of respiratory infection at Queen Mary University of London, told Healthline he believes the data is good news.
The research indicated there was a 38 percent reduction in COVID-19 risk for people with asthma; a 23 percent decrease for people with allergies such as eczema, hay fever, or rhinitis; and a 53 percent decrease for people taking immunosuppressants.
“At the start of the pandemic, there was a concern that people with airway disease such as asthma and COPD might be at heightened risk of getting severe COVID-19 — since respiratory viruses in general are known to be the major precipitant of acute exacerbations or attacks characterized by worsening of symptoms,” Martineau said.
Since then, he said, chronic obstructive pulmonary disease (COPD) has remained a risk factor for COVID-19 severity, but allergic, or type 2, asthma is not associated with more severe disease.
A number of studies have shown that allergic inflammation in the airway is associated with decreased expression of ACE2, the receptor for SARS-CoV-2, Martineau explained.
“This may explain the protective association that we saw between allergic disease and decreased risk of developing COVID-19,” he said.
However, he clarified that this is not all types of asthma.
“In asthma, the protective association seems to be for allergic or type 2 asthma specifically. Those with non-type 2 asthma tend to have an inflammatory response more similar to patients with COPD, which associates with poorer outcomes of COVID-19,” he said.
Dr. William Schaffner, an infectious disease expert at Vanderbilt University in Tennessee, heralded the study as one of the most “comprehensive and thorough studies” done on this topic.
“This reinforces observations made from others,” Schaffner told Healthline. “And confirmation in science is very important.”
However, Schaffner said there is more to be studied before people with allergies or asthma and those taking immunosuppressants change their daily routines.
“It’s provocative and curious,” he said of the data around.
But he points out that it’s a small part of a big study, and perhaps not a significant breakthrough yet.
“The fact that the authors give [these conditions] only two sentences in (a long) study indicates to me that, like the rest of us, they are scratching their heads a little bit about this,” he explained.
Schaffner said he hopes to see more research and confirmation by others because the possibility is “very interesting if true.”
Martineau said the study was careful to take into account as many aspects of life as they could, including things such as transportation choices, workplace setup, and other daily habits.
“We adjusted for behaviors that increased risk of SARS-CoV-2 exposure, such as public transport use and indoor visits to public places and other households,” he said. “In other words, we saw a protective association after adjusting for numerous factors linked to risk of SARS-CoV-2 exposure.”
Schaffner said he would want further studies to dig deeper into this issue.
Could people who already have comorbidities that initially were thought to put them at higher risk just naturally protect them more?
He’s particularly interested in those who take immunosuppressive drugs.
Martineau said the study team does not see this — in any way — as a hint that mitigation measures such as vaccines and physical distancing are not vital.
“I would emphasize that the degree of protection is quite modest — much less than that afforded by vaccination against (COVID-19),” he said.
“I would not want people with allergies to get the message that they are strongly resistant to (COVID-19). Vaccination and public health measures like avoiding indoor mixing at times when disease rates are spiking should be adhered to by people with and without allergies in order to minimize the risk of contracting COVID-19,” he added.
Schaffner points to another positive this study could bring: better understanding and pathways toward treatment.
“Knowing this kind of thing is good,” he said. “By studying diseases and who is more or less susceptible (to COVID-19), you may give yourself a lead in how to fight it.”
“In this context, this is important stuff,” he added.