Pre-Existing Allergies Patients with Higher Viral Load and Longer Recovery Days Infected by SARS-CoV-2 Omicron BA.2 in Shanghai, China, 2022

BACKGROUND: It is not known whether the viral load and the number of days to negative nucleic acid increased in patients with a history of allergy during the COVID-19 pandemic. OBJECTIVE: To investigate the impact of allergy labels on SARS-CoV-2 Omicron outcomes. METHODS: This retrospective cohort study included 62,293 patients with mild Omicron infection between April 9, 2022, and May 31, 2022. Using 1:2 propensity score matching, we identified 2177 COVID-19 patients with a history of allergy and 4254 COVID-19 patients with no history of allergy. The differences in viral load, days to nucleic acid turning negative, and clinical symptoms were compared between the two groups. RESULTS: Compared with the group with no allergies, the number of days before negative nucleic acid conversion of COVID-19 patients with allergies was significantly higher, the viral load was significantly higher, and the cumulative negative conversion rates at 5–10 days were all lower (p < 0.01). Patients with a history of allergy to antibiotics had higher viral load and more days with negative nucleic acid levels (p < 0.001). Subgroup analysis revealed that the viral load in penicillin-allergic and cephalosporins-allergic patients was significantly compared to patients without any history of allergies (p < 0.05). CONCLUSION: Patients with a history of allergy have a more significant viral load and a longer duration of nucleic acid negative conversion upon COVID-19 infection, particularly those allergic to antibiotics.