Review Meningococcal disease burden and transmission in crowded settings and mass gatherings other than Hajj/Umrah: A systematic review Al-Mamoon Badahdah a,b,c,⇑ , Harunor Rashid a,b,d , Ameneh Khatami b,e , Robert Booy a,d,f,g a National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases (NCIRS), The Children’s Hospital at Westmead, The University of Sydney, NSW, Australia b Discipline of Child and Adolescent Health, Sydney Medical School, University of Sydney, NSW, Australia c Department of Family and Community Medicine, Faculty of Medicine in Rabigh, King Abdulaziz University, Jeddah, Saudi Arabia d Marie Bashir Institute for Infectious Diseases and Biosecurity, School of Biological Sciences and Sydney Medical School, University of Sydney, NSW, Australia e Departments of Paediatric Infectious Diseases and Microbiology, School of Medicine, NYU Langone Medical Centre, NY, USA f WHO Collaborating Centre for Mass Gatherings and High Consequence/High Visibility Events, Flinders University, Adelaide 5001, Australia g NHMRC Centre for Research Excellence – Immunisation in Understudied and Special Risk Populations: Closing the Gap in Knowledge Through a Multidisciplinary Approach, School of Public Health and Community Medicine, Faculty of Medicine, University of New South Wales, Sydney, Australia article info Article history: Received 12 March 2018 Accepted 11 June 2018 Available online 28 June 2018 Keywords: Mass gathering Gathering Crowd Camp Sports Travel Meningococcal disease N. meningitidis abstract Background: Mass gatherings (MGs) such as the Hajj and Umrah pilgrimages are known to amplify the risk of invasive meningococcal disease (IMD) due to enhanced transmission of the organism between attendees. The burden of IMD at MGs other than Hajj and Umrah has not previously been quantified through a systematic review. Methods: A systematic search for relevant articles in PubMed and Embase was conducted using MeSH terms; this was buttressed by hand searching. Following data abstraction, a narrative synthesis was con- ducted to quantify the burden of IMD at MGs and identify potential risk factors and mitigation measures. Results: Thirteen studies reporting occurrence of IMD at MGs or similar crowded settings were identified. Eight studies reported cases or outbreaks in MGs of 1000 people; five others reported IMD in other crowded settings; all occurred between 1991 and 2015. All age groups were involved in the identified studies; however the majority of cases (80%) were young people aged 15–24 years. The number of affected people ranged from one to 321 cases and the overall crude estimate of incidence was calculated as 66 per 100,000 individuals. Serogroups A, C, B and W were identified, with serogroups A and C being most common. Of 450 cases of IMD reported in non-Hajj/Umrah MGs, 67 (14.9%) had fatal outcomes. Conclusion: IMD outbreaks at non-Hajj/Umrah MGs are generally much smaller than Hajj-related outbreaks and affect mainly young people. Health education and vaccination should be considered for attendees of high risk non-Hajj/Umrah MGs, especially those involving adolescents and young adults. Ó 2018 Elsevier Ltd. All rights reserved. Contents 1. Introduction ........................................................................................................ 4594 2. Methods ........................................................................................................... 4594 2.1. Search strategy ................................................................................................ 4594 2.2. Study selection ................................................................................................ 4594 2.3. Data extraction ................................................................................................ 4594 2.4. Quality assessment ............................................................................................. 4594 https://doi.org/10.1016/j.vaccine.2018.06.027 0264-410X/Ó 2018 Elsevier Ltd. All rights reserved. ⇑ Corresponding author at: National Centre for Immunisation Research and Surveillance of Vaccine Preventable Diseases (NCIRS), Kids Research Institute at The Children’s Hospital at Westmead, Cnr Hawkesbury Road and Hainsworth Street, Westmead, Locked Bag 4001, Westmead, NSW 2145, Australia. E-mail address: mbadahdah@hotmail.com (A.-M. Badahdah). Vaccine 36 (2018) 4593–4602 Contents lists available at ScienceDirect Vaccine journal homepage: www.elsevier.com/locate/vaccine