Daijiworld Media Network - New Delhi

New Delhi, Oct 5: A new study has found that SARS-CoV-2 infection may be associated with an increased risk of developing six allergic conditions in children and adults, suggesting that the health effects of COVID-19 may extend beyond the acute phase of the infection.

The study, published in the Annals of Allergy, Asthma & Immunology, examined the potential burden of allergic diseases following COVID-19 infection among people aged one to 64 years.

Researchers conducted a retrospective cohort study using 1:2 propensity-score matching to assess the association between COVID-19 infection and the development of allergic conditions over an 18-month period.

The study found that people who had COVID-19 faced an increased risk of six allergic conditions — atopic dermatitis, asthma, food allergy, rhinoconjunctivitis, medication allergy and urticaria, commonly known as hives.

Among active-duty participants, asthma and rhinoconjunctivitis were significantly associated with previous COVID-19 infection. Among children, all the allergic conditions except food allergy showed a significant association with prior infection.

The researchers also found that higher sponsor rank, which was assessed as a potential indicator of socioeconomic status, was associated with a slight protective effect against developing asthma.

Researchers from the Division of Pulmonary and Sleep Medicine at the Department of Pediatrics, University of Washington School of Medicine, said the findings point to a potential public health burden from allergic diseases following COVID-19 infection.

They stressed the importance of monitoring people after infection for allergic conditions so that they can be identified and treated promptly.

The findings may also point to a possible link between SARS-CoV-2 infection and type 2 inflammation, an immune pathway involved in several allergic diseases. Researchers noted that the virus has been shown to disrupt immune responses and affect multiple organs during and after infection.

The immune effects of COVID-19 were observed early in the pandemic in conditions such as multisystem inflammatory syndrome in children (MIS-C). Later, long COVID emerged, with symptoms including fatigue, persistent cough, breathlessness, nasal congestion, runny nose and skin rashes.

According to allergy and asthma specialist Dr Alan Khadavi, several factors could potentially explain the association between COVID-19 and allergic diseases.

One possibility is that SARS-CoV-2 may alter immune regulation and promote type 2 inflammation. The infection may also activate mast cells, which release histamine and other inflammatory chemicals and can contribute to symptoms such as itching, hives, nasal congestion and wheezing.

Inflammation in the nose, sinuses and lungs following COVID-19 could potentially make the respiratory system more sensitive to environmental triggers. Pandemic-related lifestyle changes also resulted in people spending more time indoors, potentially increasing exposure to dust mites, pets, mould, cockroach allergens and indoor air pollutants.

Respiratory viruses are already known to trigger asthma flare-ups. According to Khadavi, COVID-19 could add to this risk if immune changes persist in some people after infection.

However, the researchers cautioned that the study found an association and does not establish causation. Its retrospective design means it cannot prove that COVID-19 directly causes allergic diseases or confirm that type 2 inflammation is the underlying mechanism.