Risk Factors Associated with Cutaneous Reactions Following COVID-19 Vaccine Immunisation: A Registry-Based Case-Control Study.

Background: In Malaysia, following extensive COVID-19 vaccination, Hospital Kuala Lumpur reported an increase in cutaneous reactions post-immunisation. To understand this, a case-control study was initiated to identify potential risk factors.

Methods: This registry-based, unmatched case-control study encompasses all adverse event following immunisation (AEFI) reports associated with COVID-19 vaccines, received by the Department of Pharmacy at Hospital Kuala Lumpur through the Malaysian Adverse Drug Reactions Advisory Committee (MADRAC) AEFI reporting forms. Twenty-four potential risk factors were evaluated, including demographic information, medical history, food allergies, COVID-19 vaccination history and prior SARS-CoV-2 infection, were evaluated using MADRAC AEFI reporting forms. Odds ratio (OR) with 95% confidence interval (CI) were estimated using univariable and multivariable logistic regression.

Results: Cutaneous reactions were more frequent in middle-aged females, especially after the first COVID-19 vaccine dose. These reactions, primarily mild and generalised, included pruritus and urticaria. Notably, 52% were delayed reactions (more than 4 h post-vaccination). Factors associated with increased risk of cutaneous reaction following COVID-19 immunisation included history of seafood and shellfish allergy (adjusted odds ratio [adjOR]: 2.11; 95% CI: 1.12, 3.96; P = 0.020), history of vaccine allergy (adjOR: 4.07; 95% CI: 1.44, 11.54; P = 0.008), past dermatological diseases (adjOR: 5.48; 95% CI: 2.03, 14.78; P = 0.001), and past medication allergy (adjOR: 2.12; 95% CI: 1.36, 3.31; P = 0.001).

Conclusion: Self-reported histories of allergies to vaccines, foods or medications were found to increase the likelihood of cutaneous reactions following COVID-19 vaccination. These reactions, which were predominantly mild, did not hinder the administration of the second vaccine dose. The majority of reactions occurred after the first dose, manifesting as generalised pruritus and urticaria. They were effectively managed with oral antihistamines and low-dose corticosteroids, thereby avoiding the need for hospitalisation.