Prevalence of respiratory viruses among pilgrims in Saudi Arabia during the Hajj 2026: a cross-sectional study

Abstract Background Hajj is one of the world's largest annual mass gatherings and provides favorable conditions for respiratory virus transmission because of intense crowding and extensive international travel. Contemporary post-pandemic molecular surveillance data remain limited. This study investigated the prevalence, determinants, and characteristics of respiratory virus detections among pilgrims during the 2026 Hajj season. Methods A cross-sectional study was conducted among adult domestic and international pilgrims over an extended peri-Hajj period (before, during and after Hajj) in the year 2026. Participants completed a structured questionnaire and provided combined nasopharyngeal and oropharyngeal swab specimens for multiplex real-time RT-PCR detection of common respiratory viruses. A subset of positive samples underwent genomic sequencing for viral subtype and variant characterization. Logistic regression was used to identify factors associated with laboratory-confirmed respiratory viral infection. Results Among 412 enrolled pilgrims across all three phases, 58 (14.1%) tested positive for at least one respiratory virus. The prevalence of viral detection was 6.7% pre-Hajj, 16.0% during Hajj and 21.4% post-Hajj. Influenza A was the predominant virus (34.5%), followed by rhinovirus (24.1%), SARS-CoV-2 (20.7%), respiratory syncytial virus (13.8%), adenovirus (5.2%), and seasonal human coronaviruses (1.7%). Diabetes mellitus, chronic lung disease and smoking were independently associated with increased odds of respiratory virus detection. Conversely, receipt of pre-travel health advice, influenza vaccination and regular facemask use were independently associated with reduced odds of respiratory virus detection. Conclusions Respiratory virus transmission remains an important public health concern during Hajj. Strengthening pre-travel health advice, promoting influenza vaccination, and reinforcing personal preventive measures may reduce respiratory viral transmission during Hajj and other international mass gatherings.