Preexisting asthma or rhinitis risk factor for Long Covid

An allergic reaction is the robust response of the immune system hypersensitive to foods, pollen, medications, bee venom, and other substances. Exposure to these allergens can lead to swelling, hives, and other symptoms. Long-COVID (LC) is a term developed by the patient community which is not well agreed definition. It is broadly defined as signs, symptoms, and sequelae that continue or develop after acute COVID-19 or SARS-CoV-2 infection.

A recent study in Clinical and Experimental Allergy reports that prexisting conditions like asthma, rhinitis can be a increasing risk factor for Long covid and its consequences.

Researchers conducted an initial systematic review. Two reviewers independently performed the study selection and data extraction using Covidence. Risk of bias (RoB) and certainty of evidence (GRADE) were assessed. Random effects meta-analyses were used to pool unadjusted ORs within homogeneous data subsets. Data Sources were collected from retrieved articles published between January 1st, 2020 and January 19th, 2023 from MEDLINE via PubMed, Scopus, the WHO-COVID-19 database and the LOVE platform (Epistemonikos Foundation). In addition, citations and reference lists were searched.

They included included prospective cohort studies recruiting individuals of all ages with confirmed SARS-CoV-2 infection that were followed up for at least 12 months for LC symptoms where information on pre-existing allergic diseases was available. They excluded all study designs that were not prospective cohort studies and all publication types that were not original articles.

The key findings of the study are

• They identified a total of 13 studies (9967 participants, range 39–1950 per study), all assessed as high RoB, due to population selection and methods used to ascertain the exposures and the outcome.

• Four studies did not provide sufficient data to calculate Odds Ratios. The evidence supported a possible relationship between LC and allergy, but was very uncertain.

• For example, pre-existing asthma measured in hospital-based populations (6 studies, 4019 participants) may be associated with increased risk of LC (Odds Ratio 1.94, 95% CI 1.08, 3.50) and findings were similar for pre-existing rhinitis (3 studies, 1141 participants; Odds Ratio 1.96, 95% CI 1.61, 2.39), both very low certainty evidence.

Researchers concluded that “Pre-existing asthma or rhinitis may increase the risk of LC.”

Reference: Doreen Wolff, Karl Philipp Drewitz, Angela Ulrich, Doreen Siegels, Stefanie Deckert, Antonia Anabella Sprenger, Paula Ricarda Kuper, Jochen Schmitt, Daniel Munblit, Christian Apfelbacher; Allergic diseases as risk factors for Long-COVID symptoms: Systematic review of prospective cohort studies; Clin. Exp. Allergy November 2023 DOI: https://doi.org/10.1111/cea.14391.