In an analysis of 13 published prospective studies of people of all ages with confirmed SARS-CoV-2 infection who were followed for at least 12 months, pre-existing allergic conditions were associated with increased risks of experiencing long COVID, according to one study. today in Clinical and experimental allergy.
This is one of the first studies to evaluate the relationship between long COVID and allergies.
The studies included 9,967 participants and were published from January 1, 2020 to January 19, 2023. For long COVID, the authors used a definition of self-reported or doctor-diagnosed symptoms that continue or develop after infection. acute onset of COVID-19.
In the 13 included studies, the proportion of people with long COVID ranged from 11% to 90%, with a median of 53.3%. Study sample sizes ranged from 39 to 2,826 people.
Associations with asthma, allergic rhinitis.
Four of the 13 studies provided estimates on the association between pre-existing allergic conditions, such as asthma or hay fever, and long COVID. Pre-existing asthma was associated with an increased risk of long COVID, but the evidence was very uncertain, the authors said. The odds ratio (OR) for pre-existing asthma and long COVID was 1.94 (95% confidence interval). [CI]1.08 to 3.50).
In an analysis of three studies that included data on preexisting allergic rhinitis, the condition was significantly associated with an increased risk of long COVID (OR, 1.96; 95% CI, 1.61-2.39).
We need a better, harmonized definition of what is considered long COVID for epidemiological studies of this type.
Only 3 of the 13 studies measured long COVID with physical exams and completed questionnaires, the authors noted. Furthermore, among the 13 studies, the authors found a high risk of bias due to patient selection (mostly hospitalized patients) and loss to follow-up.
“We need a better, harmonized definition of what is considered long COVID for epidemiological studies of this type. Regardless, we will update our analysis once more studies have been published in the coming months,” said lead author Christian Apfelbacher, PhD. . of the German Research Institute for Social Medicine and Health Systems, in a press release about the study from the journal’s editor.