Prevention of respiratory viral infection among Hajj pilgrims

Hajj is one of the five basic tenets of Islam. Every practicing, financially and physically capable, Muslim is required to perform Hajj at least once in his/her lifetime. Each year up to three million people from more than 180 countries assemble in Mecca, Saudi Arabia, to perform Hajj pilgrimage. Severe crowding, shared accommodation, poor personal hygiene, and environmental pollution at Hajj may collectively lead to increased transmission of respiratory viruses. Influenza-like illness (ILI) is one of the most common medical presentations to primary care, mostly due to viral infection, in which pneumonia is the leading cause of hospital admission during Hajj. Therefore, I endeavoured to study the epidemiology of respiratory viruses among pilgrims including newly emergent viruses such as Middle East coronavirus (MERS-CoV) and assessed preventive strategies primarily focussing on facemasks effectiveness and evaluating influenza vaccine uptake. Methods To understand the epidemiology of respiratory infection during Hajj, a cross-sectional study was conducted among pilgrims from Saudi Arabia, Australia and Qatar. A nasal swab was collected from any participant who developed ILI to identify the causative agent. After that, we explored the possible preventive measures to reduce the transmission of respiratory viral infection such as influenza vaccine and facemasks. For influenza vaccine, an anonymous survey was conducted to assess the uptake of influenza vaccine, and explore the attitudes and barriers to, and perception of vaccination. At the same time, a pilot trial was conducted to explore the feasibility of establishing a large-scale trial to test the effectiveness of facemasks in preventing respiratory viral infection among Hajj pilgrims. The outcome of the pilot trial was encouraging and suggested that it was feasible to do a large-scale trial. Therefore, we conducted a large-scale randomised controlled trial (RCT) to test the effectiveness of facemasks in preventing respiratory viral infection over three consecutive Hajj seasons (2013, 2014, 2015). Results In 2013, we recruited 1038 pilgrims from Saudi Arabia, Australia and Qatar during the first day of Hajj and followed them closely for four days to comprehend the epidemiology of respiratory viral infection during the Hajj. About 11% of the pilgrims reported ILI; 38% of which had laboratory-confirmed viral infections. Rhinovirus was the commonest cause of ILI among Hajj pilgrims (25%) followed by influenza A (4%). Also, other types of viruses were reported such as adenovirus (2%), human coronavirus OC43/229E (2%) and parainfluenza virus 3, 1 (2%). MERS-CoV was considered a health risk at that year (2013), luckily, it was not detected in any sample in this study. The studies showed that influenza vaccine uptake was increased among Hajj pilgrims specifically the Australian. On the other hand, symptoms of respiratory infection were decreased. However, it is uncertain if this decrease is due to vaccination. Contrarily, facemasks uptake among Hajj pilgrims remained unchanged in the last 10 years with an average uptake of 50% according to a systematic review synthesised by myself and colleagues. Moreover, the large-scale RCT showed that pilgrims did not use facemasks adequately; and those who used facemasks had no statistically significant benefit against laboratory-confirmed or clinical viral respiratory tract infections. Conclusion Epidemiology of virus infection during Hajj showed that rhinovirus was the most common causative agent. Also, there were other respiratory viruses reported including influenza, adenovirus but not MERS-CoV. Influenza vaccine uptake is improving among Hajj pilgrims, while facemasks had lower uptake. Facemasks use did not prevent clinical or laboratory-confirmed respiratory viral infection during Hajj. This is may be due to poor compliance of pilgrims in using facemasks