Bacterial respiratory carriage in French Hajj pilgrims and the effect of pneumococcal vaccine and other individual preventive measures: A prospective cohort survey

Background: Viral respiratory tract infections are known to be common in Hajj pilgrims while the role of bacteria is less studied. Methods: Clinical follow-up, adherence to preventive measures and PCR-based pharyngeal bacterial carriage pre- and post-Hajj, were assessed in a cohort of 119 French Hajj pilgrims. Results: 55% had an indication for pneumococcal vaccination. Occurrence of respiratory symptoms was 76.5%, with cough (70.6%) and sore throat (44.5%) being the most frequent; fever was reported by 38.7% pilgrims and 42.0% took antibiotics. Respiratory symptoms, fever and antibiotic intake were significantly more frequent in pilgrims with indication for vaccination against pneumococcal infection. The prevalence of S. pneumoniae carriage (1.8% pre-, 9.8% post-Hajj), H. influenzae carriage (0.9%, 45.4%) and K. pneumoniae (2.8%, 9.8%) significantly increased post-Hajj. Pilgrims vaccinated with conjugate pneumococcal vaccine were seven time less likely to present S. pneumoniae carriage post-Hajj compared to those not vaccinated (3.2% vs. 18.0%, OR = 0.15; 95% CI [0.03-0.74], p = 0.02). Conclusions: Pilgrims at risk for pneumococcal disease are more likely to suffer from febrile respiratory symptoms at the Hajj despite being immunized against pneumococcal disease and despite lowered S. pneumoniae carriage and should be targeted for reinforced prevention against respiratory infections.