Sensitization rates to aeroallergens increased in Chicago after COVID-19 pandemic

Key takeaways:

• Changes in weather patterns have included increased rainfall and flooding.
• There were no changes in indoor aeroallergen sensitization patterns.
• More patients may present with allergic rhinitis symptoms.

BOSTON — Rates of sensitizations to outdoor aeroallergens increased in Chicago following the COVID-19 pandemic, according to an abstract presented at the American College of Allergy, Asthma & Immunology Annual Scientific Meeting.

Climate change may be driving these increases, Kylie Jungles, MD, second-year fellow in allergy and immunology, PGY-5, Rush Medical College of Rush University, and colleagues wrote.

“In Chicago, we’ve been seeing a great deal of patients presenting to the allergy clinic with worsening allergic rhinitis symptoms over the past few years,” Jungles, who also is the junior fellow-in-training representative for the ACAAI Board of Regents, told Healio.

Kylie Jungles

During this time, Jungles continued, she and her colleagues also have been experiencing changes in weather patterns, including increased average rainfall and flooding events.

“There have been recent studies highlighting the impact of climate change on pollen and mold proliferation patterns, so we wanted to further investigate whether these changes in climate may be impacting the allergic rhinitis symptoms our patients have been experiencing,” Jungles said.

The retrospective chart review examined data from 1,052 pediatric and adult patients (~73% female; 42% white) who had nasal allergies seen at an allergy center in Chicago between 2014 and 2019, which the researchers called the pre-COVID era, and between 2022 and 2024, known as the post-COVID era.

Blood tests were conducted for all the patients.

“Patients were excluded from the study if they did not have in vitro aeroallergen testing data confirming diagnosis of allergic rhinitis,” Jungles said.

Sensitization rates during the pre-COVID era included 49.3% for tree pollen, 54.1% for weed pollen, 57.7% for grass pollen and 46.5% for mold. In the post-COVID era, rates included 69.8% for tree pollen, 76.1% for weed pollen, 100% for grass pollen and 76.7% for mold.

There were no significant differences in sensitizations to cat and dog allergens, which the researchers considered indoor aeroallergens.

The researchers said that changing patterns of pollen and mold proliferation following increases in temperatures and rainfall as well as rising water levels in Chicago may be causing these increases in sensitization, although more research is necessary to investigate the impact that climate change is having on these rates.

“It is possible that there are additional confounding factors, which may have impacted the results of our study,” Jungles said.

Jungles said that the lack of an increase during the post-COVID timeframe in sensitization to indoor allergens such as pet dander and dust mites was interesting.

“While it’s possible that spending more time indoors may be contributing to our results, we think this is less likely, as we would expect to see an increase in indoor allergen sensitization as well,” she said.

Jungles also said that she and her colleagues hope that physicians can use these data to inform patient care.

“Due to changes in aeroallergen sensitization, we may be seeing more patients presenting with allergic rhinitis symptoms, which would prompt aeroallergen testing and treatment,” she said.

Because of the changing patterns of pollen and mold proliferation, in addition to changing temperatures, patients also may experience longer allergy seasons compared with previous years, Jungles added.

“In Chicago specifically, we are seeing patients with ragweed and mold allergy experiencing allergic rhinitis symptoms well into October/November due to warmer fall weather,” she said. “It’s important for providers to keep these changes in mind when treating allergic rhinitis.”

Jungles and her colleagues plan on continuing their research.

“The next step in our project is analyzing how climate change may be impacting the health of various neighborhoods in Chicago, and to investigate whether vulnerable communities may be more significantly impacted by the changing climate,” she said.

This research is currently under consideration for presentation at the 2025 American Academy of Allergy, Asthma & Immunology/World Allergy Organization Joint Congress.

Reference:

• Study shows rates of sensitization in Chicago to outdoor allergens increased post-COVID. (URL) Published Oct. 24, 2024. Accessed Oct. 24, 2024.

For more information:

Kylie Jungles, MD, can be reached at Kylie_N_Jungles@rush.edu.