Comparison of viral respiratory pathogens circulation among Iranian pilgrims during two large religious mass gatherings: the Hajj and Arbaeen walk 2025.

BACKGROUND: The Hajj and Arbaeen walk pilgrimages are significant religious mass gatherings (MGs) among Muslims. Respiratory tract infections (RTIs) remain a major concern during such events. This study aimed to evaluate the prevalence of respiratory viral infections among Iranian pilgrims during the 2025 Hajj and Arbaeen walk. METHODS: Throat swabs were collected from 110 symptomatic Iranian pilgrims returning from these MGs. Molecular techniques were used to detect respiratory viruses. RESULTS: A total of 60 Hajj pilgrims and 50 Arbaeen walk pilgrims, with an age range 8 to 82 years for the combined groups, participated. Rhinovirus was the most common virus detected among symptomatic pilgrims in both MGs. Notably, the rate of SARS-CoV-2 infection was 1.7% in Hajj pilgrims and 32% in Arbaeen pilgrims. Co-infections of rhinovirus and SARS-CoV-2 were identified in 8% of Arbaeen pilgrims. Additionally, coronavirus OC43/HKU1, influenza A (H3N2), and influenza B virus were detected at low frequencies. No cases of MERS-CoV were found among the 2025 Hajj pilgrims. CONCLUSION: These findings provide preliminary data on the circulation of respiratory viruses during religious MGs in 2025. Continued surveillance is essential to reduce respiratory infection risks during such mass gatherings.