Introduction
Mass-gathering events (MGEs), such as festivals, parades, sporting events, and religious events, occur regularly throughout the world. Some MGEs may have a local community focus, while others may be of international significance. Regardless, MGEs may strain the health resources of the host community, state, or nation; 1 in particular, the emergency health resources. Reference Ranse, Hutton and Keene2 This strain on health resources is an interplay between characteristics of the MGE, the participants, and the host community. Reference Lund, Turris and Bowles3 These characteristics have previously been described in detail in the biomedical, Reference Ranse, Hutton, Turris and Lund4 environmental, Reference Hutton, Ranse, Gray, Turris, Lund and Munn5 and psychosocial Reference Hutton, Ranse, Gray, Turris, Lund and Munn6 domains as a way of identifying factors that contribute to health service usage.
Mass-gathering events, by virtue of people congregating together in a common place, may result in an increased transmission of communicable diseases, particularly respiratory tract infections. Reference Ahmed, Arabi and Memish7,Reference Gautret and Steffen8 Transmission of respiratory viruses such as human coronavirus, seasonal influenza virus, and rhinovirus has been reported in various MGE contexts with varying rates of transmission. Reference Al-Tawfiq, Benkouiten and Memish9 However, novel respiratory viruses pose a unique public health threat due to a lack of treatment options and preventative measures, such as vaccines, as well as unknown modes of transmission and virulence of the pathogen involved. As such, novel respiratory viruses may require unique mitigation strategies for MGE planning from a health perspective, particularly due to the possibility of rapid spread and pandemic potential when compared to other communicable diseases. Reference Al-Tawfiq, Benkouiten and Memish9
Several novel respiratory viruses of global concern have emerged over the past two decades. A novel virus is identified when the genomic sequencing of a virus demonstrates the characteristics of a typically known virus, however, the genomic characteristics of the virus is distinctly different from all known previously sequenced viruses. Reference Rota, Oberste and Monroe10 Emerging in Asia in 2002, a novel coronavirus was identified and designated as Severe Acute Respiratory Syndrome (SARS) Coronavirus-1, or SARS-CoV-1, and resulted in a global mortality of 774, with a case fatality rate of 9.6% that increased with age. Reference Chan-Yeung and Xu11 In 2009, a novel influenza A was identified in South America and was designated as an Influenza A Subtype Strain, or H1N1pdm09. In its first 12 months, the H1N1pdm09 virus resulted in a pandemic with an estimated global mortality of 201,200 (range 105,700-395,600) from respiratory causes and 83,300 (range 46,000-179,900) from cardiovascular causes. Reference Dawood, Iuliano and Reed12 In 2012, a novel coronavirus was identified and designated as Middle East Respiratory Syndrome Coronavirus (MERS-CoV). Reference Donnelly, Malik, Elkholy, Cauchemez and Van Kerkhove13 Since its emergence, this virus has resulted in approximately 2,519 cases of which 866 died. 14 More recently, in March 2020, the World Health Organization (WHO; Geneva, Switzerland) characterized a novel coronavirus originating in China as SARS-CoV-2, which causes coronavirus disease 2019 (COVID-19). The WHO declared the virus a public health emergency of international concern, in line with the International Health Regulations, 15 and later a pandemic. As of November 22, 2020, COVID-19 has resulted in 57,882,183 global cases of infection and 1,377,395 deaths. 16
Novel respiratory viruses, such as SARS-CoV-1, H1N1pdm09, MERS-CoV, and SARS-CoV-2, may have an impact on MGEs. As novel respiratory viruses emerge, there will continue to be a threat to the public health of MGE attendees, the host communities where MGEs are held, and the home communities where MGE attendees return. Infection prevention and control strategies to minimize the risk of transmission of novel respiratory viruses should be key planning considerations for future MGEs.
Aim
The aim of this literature review was to identify papers relating to novel respiratory viruses with pandemic potential and MGEs. The objective was to analyze these identified papers for infection prevention and control strategies to inform planning before, during, and following MGEs to limit the transmission of these viruses.
Methods
Design
This systematic literature review was guided by the Preferred Reporting Items of Systematic Reviews and Meta-Analysis (PRISMA) Guidelines. Reference Moher, Liberati, Tetzlaff, Altman and Prisma17
Data Collection
Health care databases included in this review were Medical Literature Analysis and Retrieval System Online (MEDLINE; US National Library of Medicine, National Institutes of Health; Bethesda, Maryland USA), Cumulative Index to Nursing and Allied Health Literature (CINAHL; EBSCO Information services; Ipswich, Massachusetts USA), and Scopus (Elsevier; Amsterdam, Netherlands). The search strategy included different combinations of Medical Subject Headings (MeSH) terms and keywords that were relevant to MGEs and novel respiratory viruses, and they are outlined in Table 1. The MeSH terms and keywords in the columns were combined using the OR Boolean operator, while the MeSH terms and keywords in the rows were combined using the AND Boolean operator. Wildcards, such as an asterisk, were used for all keywords.
Table 1. Search MeSH Terms and Keywords

Abbreviations: MeSH, medical subject headings; SARS, Severe Acute Respiratory Syndrome; MERS, Middle East Respiratory Syndrome; COVID-19, coronavirus disease 2019.
Inclusion criteria for this literature review were articles published in English priori to October 12, 2020, reporting primary data on real-world MGEs, and where novel respiratory virus were included. Papers were excluded from this review if they were discussion papers or theoretical papers, such as modelling or prediction focused.
Data Analysis
Information extracted from each paper was entered into a Microsoft Word 2018 table (Microsoft Corporation; Redmond, Washington USA). Two tables were generated. The first table included information relating to the publication characteristics, mass-gathering characteristics, and novel respiratory virus epidemiology. This table is divided into different novel respiratory viruses based on the research study aims, such as SARS-CoV-1, H1N1pdm09, MERS-CoV, and SARS-CoV-2. The second table was developed based on the Haddon Matrix that identifies public health strategies during the different phases of an MGE Reference Hutton, Savage, Ranse, Finnell and Kub18 and the ten essential public health operations to deliver public health services. 19 The latter can be grouped into three key areas, including intelligence (surveillance, monitoring); service delivery (health promotion, health protection, disease prevention); and enablers (governance, workforce, funding, communication, research).
Results
In total, 27 papers met the criteria for inclusion, reporting on 28 MGE (Figure 1). The MGE and virus epidemiology were extracted from the 27 papers (Table 220- 46). The majority of MGEs were religious in nature (n = 22/28; 78.6%) with one-half of the MGEs studies undertaken in the Kingdom of Saudi Arabia (n = 14/28; 50.0%). While the aim of this review was to identify papers that reported on novel respiratory viruses with pandemic potential, many papers also reported on seasonal influenza or other respiratory viruses (n = 18/28; 64.3%). Further, more than one-half (n = 8/15; 53.3%) of the papers focusing on MERS-CoV also included the reporting of H1N1pdm09, as at the time of MERS-CoV, H1N1pdm09 was no longer a novel virus, but instead a more common influenza strain. Finally, infection prevention and control strategies were extracted utilizing the WHO essential public health operations (Table 3) to inform this literature review.

Figure 1. Modified PRISMA Flow Diagram. Reference Moher, Liberati, Tetzlaff, Altman and Prisma17
No papers were identified regarding SARS-CoV-1 in the context of MGEs.
H1N1pdm09
A total of nine papers, reporting on ten MGEs, were published that aimed to investigate H1N1pdm09. Of these, five (n = 5; 50.0%) were from religious MGEs, mostly reporting from the Hajj in the Kingdom of Saudi Arabia. The MGEs published relating to H1N1pdm09 ranged in duration from four days to twelve days. The presence of H1N1pdm09 varied depending on the testing strategies, ranging from 0.0% to 40.0% (n = 12/30) among MGE attendees with influenza-like illness (ILI). Of these samples, seasonal respiratory viruses were identified ranging from 12.2% (n = 62/519) to 38.8% (n = 87/227). A number of intelligence, service delivery, and enabler public health operations were identified before, during, and after the MGEs that supported infection prevention and control strategies during the H1N1pdm09 pandemic. These strategies are presented in Table 3 and included epidemiological surveillance, provision of vaccinations, restriction of attendance, collaboration between the event health providers and Ministries or Departments of Health, establishment of an in-event medical center, implementation of guidelines for diagnosis and referral, and communication with MGE attendees.
MERS-CoV
In total, 15 papers aimed to investigate MERS-CoV in the context of MGEs. All 15 papers reported on religious MGEs, that being the Hajj between the years 2012 and 2015. Of these papers, the presence of MERS-CoV was not identified in any samples. However, other respiratory viruses were identified, ranging from 21.3% (n = 64/300) to 58.4% (n = 73/125). Of particular note, H1N1pdm09 was identified between 0.1% (n = 1/692) to 6.7% (n = 258/3,840). Infection prevention and control strategies identified in the 15 MERS-CoV papers included obtaining personal details, active screening at points of entry and exit, use of facemasks, encouragement of vulnerable populations not to attend, and health assessment clinics at MGEs. Additionally, many of the papers were prospectively designed with a pre- and post-MGE recruitment strategy to identify changes in respiratory virus profiles amongst MGE attendees.
SARS-CoV-2 (COVID-19)
To date, a total of three papers aimed to investigate SARS-CoV-2 in the context of MGEs. Of these, two (n = 2, 66.7%) related to religious MGEs. The presence of SARS-CoV-2 ranged from 8.9% (n = 1,701/19,032) in a religious mass gathering in Malaysia to 90.5% (n = 48/53) among pilgrims arriving to Greece from Jerusalem. During the SARS-CoV-2 pandemic, identified infection prevention and control strategies included contact tracing, self-isolation and health monitoring, and cancelling MGEs. These strategies occurred mostly after the MGE, with no strategies reported from these papers before or during MGEs.
Discussion
Given that MGEs of international significance result in the movement of people across the globe, the risk of infectious disease transmission is heightened. Reference McCloskey, Zumla and Ippolito47 As such, infection prevention and control strategies are required to assure global health security in the context of MGEs. Reference McCloskey, Zumla and Ippolito47 However, during the early evolution of a novel respiratory virus, MGE organizers, public health agencies, and government Departments of Health may make decisions to either cancel or postpone MGEs. Alternatively, they may progress with their MGEs as planned, or in a modified format. Reference McCloskey, Zumla and Ippolito47–Reference Ebrahim and Memish49 This literature review provided an overview of the novel respiratory virus epidemiology alongside public health strategies that have been implemented at MGEs in the context of novel respiratory viruses with pandemic potential. The discussion below outlines considerations for planning an MGE in the context of novel respiratory viruses with pandemic potential.
Cancel or Postpone MGEs
The papers identified in this systematic literature review did not discuss cancelling or postponing MGEs as a way of protecting the health security of the event population, population of the MGE host city/country, or global health more broadly. However, during the SARS-CoV-2 pandemic, a number of editorials have been written outlining the advantages, consequences, and decision making for cancelling or postponing MGEs. Reference McCloskey, Zumla and Ippolito47–Reference Ebrahim and Memish49 These editorials argued that either a risk assessment approach should be used to determine if MGEs should be cancelled or postponed, Reference McCloskey, Zumla and Ippolito47 or that all MGEs should be cancelled amid a novel respiratory viruses with pandemic potential and a risk assessment approach should be utilized to determine if an MGE should recommence. Reference Ahmed and Memish48,Reference Ebrahim and Memish49 Many risk assessment tools have been developed to inform health service planning for MGEs. Reference Bieh, ElGanainy and Yezli50–Reference Yezli and Khan52 However, these tools were developed and validated outside of the context of novel respiratory viruses with pandemic potential. More recently, the WHO has developed risk assessments tools and guidance specific to SARS-CoV-2 and MGEs. 53
Modifying MGEs
When considering if an MGE event should recommence, the WHO promotes decision making based on a risk assessment. Such risk assessments should consider a risk evaluation of the current pandemic situation locally, nationally, and internationally; identification of infection prevention and control strategies and MGE mitigation strategies to reduce or limit the likelihood of virus transmission; a decision matrix to determine the effectiveness of any proposed strategies; and a risk communication plan to inform event staff and attendees of modifications to an event. 53 The implementation of strategies that limit the risk of transmission of novel respiratory viruses is essential to planning and progressing with an MGE. Reference McCloskey, Zumla and Ippolito47 This literature review has identified numerous infection prevention and control strategies that have been employed during MGEs in the context of novel respiratory viruses. Many of the strategies could be employed at any MGE. Such strategies focused primarily on enablers of service delivery, for example restricting “at risk” demographics, having in-event health service, and having isolation areas at MGEs.
Legacy of MGEs
The key infection prevention and control strategies described in the literature that occur after an MGE primarily relate to the screening of participants as they depart the event host community or upon returning to their home community. Such strategies and interventions primarily included screening at departure and/or home airports, post-event surveillance, risk communication with health services, and event attendees to seek testing if ILI symptoms arise. At present, there is a paucity of research in terms of the effectiveness of post-event infection prevention and control strategies. As such, in the context of SARS-CoV-2 and future novel respiratory viruses, as MGEs recommence globally, a consistent approach to the reporting of in-event and host community infection prevention and control strategies alongside health outcomes will be important for determining strategy effectiveness. Reference Ranse and Hutton54
It is argued that the evidence base for novel respiratory viruses in the context of MGEs is evolving and needs to be more comprehensive. Reference McCloskey, Zumla and Ippolito47. As noted in Table 2, most of the MGEs reported in the included papers related to religious MGEs (n = 22/28; 78.8%) such as the Umrah, Hajj, and World Youth Day. Additional studies relating to novel respiratory viruses in the context of MGEs beyond religious MGEs are needed. This is of importance as other types of MGEs have attendees with differing population characteristics, such as different moods and motivations of the attendees Reference Hutton, Ranse, Gray, Turris, Lund and Munn6 and environmental characteristics. Reference Hutton, Ranse, Gray, Turris, Lund and Munn5 Such differing characteristics could result in the need for different mitigation interventions and strategies than what has been discussed in this paper, as these MGEs may have a different level of risk for the transmission of viruses.
Table 2. Mass-Gathering Event Characteristics and Novel Respiratory Virus Epidemiology

Abbreviations: H1N1pdm09, Influenza A Virus Subtype H1N1 Strain 2009; MERS-CoV, Middle East Respiratory Syndrome Coronavirus; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus-2; r, raw numbers only; ILI, influenza-like illness; KSA, Kingdom of Saudi Arabia; SARI, severe acute respiratory infection; COVID-19, coronavirus disease 2019.
a Duration represents the duration of the event itself, not the duration of time an event participant was in the host community or country.
b H1N1 serology type unknown, presumably H1N1pdm09.
c Before/pre-mass gathering.
d After/post-mass gathering.
Table 3. Haddon Matrix and Infection Prevention and Control Strategies

Abbreviations: H1N1pdm09, Influenza A Virus Subtype H1N1 Strain 2009; MERS-CoV, Middle East Respiratory Syndrome Coronavirus; SARS-CoV-2, Severe Acute Respiratory Syndrome Coronavirus-2; MGE, mass-gathering event; ILI, influenza-like illness.
Limitations
This literature review was restricted to papers published in English. As such, publications in other languages have not been included. Further, this literature review only included peer-reviewed literature. As such, non-indexed, or grey literature, was not included in the results of this review. Given the evolving nature of SARS-CoV-2 literature, some preliminary papers in draft would not have been included.
Conclusion
This literature review has identified papers exploring novel respiratory viruses, such as H1N1pdm09, MERS-CoV, and SARS-CoV-2, in relation to MGEs. Of note, this paper discussed decisions to cancel or postpone MGEs, ways to recommence MGEs incorporating public health and MGE specific infection prevention and control strategies, and the legacy of MGEs during a novel respiratory virus with pandemic potential. Currently, SARS-CoV-2 has significantly impacted the ability for MGEs to be held. To ensure the health security of MGE participants, risk assessments should be undertaken in collaboration between MGE organizers and health authorities, as this is key in the decision-making process to ensure future MGEs are viable, sustainable, and protect both local and global health.
Conflicts of interest
The authors declare that they have no competing interests.