Allergic Status, Long COVID, and Post-Restriction Respiratory Outcomes in Children: A Single-Center Questionnaire-Based Study

Background: The relationship between allergic status, SARS-CoV-2 infection, Long COVID, and post-restriction respiratory outcomes in children remains incompletely understood. This study aimed to explore the associations between allergic status and Long COVID, as well as between SARS-CoV-2 vaccination and post-restriction changes in allergic rhinitis (AR), asthma, and upper respiratory infections, in a pediatric tertiary-care cohort. Methods: We conducted a single-center, questionnaire-based observational study involving children aged 0–16 years, who were followed at the Pediatric Allergy Clinic of Umberto I Hospital in Rome. Parents completed an email-based questionnaire addressing SARS-CoV-2 infection, vaccination, persistent post-infectious symptoms, allergic diseases, and respiratory infections following restrictions. Analyses of Long COVID were limited to children with confirmed SARS-CoV-2 infection. Results: A total of 214 questionnaires were analyzed. Allergic status was not significantly associated with SARS-CoV-2 infection in the overall cohort. Among infected children, allergic status was independently associated with higher odds of Long COVID (adjusted OR 3.12, 95% CI 1.20–8.09; p = 0.019). Severe acute infection was also strongly associated with Long COVID (adjusted OR 6.84, 95% CI 2.72–17.21; p < 0.001). Complete vaccination was associated with lower odds of SARS-CoV-2 infection in the overall sample (adjusted OR 0.20, 95% CI 0.09–0.46; p < 0.001) but was not independently associated with Long COVID among infected children. After the removal of COVID-19 restrictions, 90.1% of allergic children reported worsening AR and 52.0% reported worsening asthma, with no significant association with SARS-CoV-2 infection or Long COVID. Group A Streptocossus (GAS) pharyngitis was reported in 50.0% and viral pharyngitis in 10.7% of the cohort, with no significant differences between allergic and non-allergic children. Conclusions: In this single-center, questionnaire-based pediatric cohort, allergic status was correlated with increased likelihood of Long COVID among children with confirmed SARS-CoV-2 infection; however, it was not associated with a higher risk of infection itself. Complete vaccination was linked to a reduced risk of infection, whereas no independent correlation with Long COVID was identified. Post-restriction exacerbation of allergic respiratory symptoms was prevalent, while the incidence of bacterial and viral pharyngitis did not vary significantly according to allergic status.