Exploring risk factors for Raynaud's phenomenon post COVID-19 vaccination

Background: Raynaud's phenomenon (RP) has recently been observed in recipients of the COVID-19 vaccine. It is unclear whether RP is directly caused by the COVID-19 vaccine. This study aims to investigate the potential causation between RP and COVID-19 vaccination. Methods: In this study, we searched PubMed, EMBASE, and Web of Science from January 1, 2020, to March 19, 2024. We included the articles with clinical related findings, specifically case reports and case series. Conference abstracts, editorial publications, preprint, and those not specifically related to COVID-19 vaccination are excluded. The refined selection process aimed to ensure a focused and clinically relevant analysis of the association between RP and COVID-19 vaccination. Results: A total of six articles were ultimately included in this study, comprising five case reports and one case series involving 24 patients with RP after vaccination. Baseline characteristics of the studies showed the RP post COVID-19 vaccination frequently occurred with females compared to males (70.83 vs. 29.17 %). Of the patients with RP post COVID-19 vaccination, 87.5 % (21/24) had either a history or possible predisposing factors of RP. Among the patients with detailed information of vaccination (n = 20), the number of vaccine doses was not related to RP development (45 % (1st) vs. 30 % (2nd) vs. 25 % 3rd dose). For types of vaccine, 75 % of RP were found to have received the administration of mRNA vaccine (15/20). Conclusion: The risk of bias was increased due to the uncontrolled study designs and small sample size, making it impossible to attribute causation between RP and COVID-19 vaccination. These few cases may have occurred independently of vaccination. However, physicians should still remain vigilant for RP following COVID-19 vaccination, particularly as the number of vaccinated individuals continues to rise.