Super-spreaders
Super-spreaders and SSEs have a significant impact on the development of a disease outbreak. The aforementioned 2003 SARS-CoV outbreak in China and 2015 MERS-CoV outbreak in South Korea both have had documented super-spreaders in the initial stages of the outbreaks. 9 More recently, Schuchat (2020) suggests that after Severe Acute Respiratory Syndrome coronavirus 2 (SARS-CoV-2) had been brought into the United States (US) by international travellers, gatherings of large crowds such as the Mardi Gras celebrations in Louisiana with one million attendees allowed for many further SSEs that greatly contributed to an increase in SARS-CoV-2 cases in the US, accelerating its spread and resulting in an epidemic. In addition, when using local contact-tracing data from Hong Kong during the 2020 SARS-CoV-2 outbreak, Adam et al. (2020) found that twenty percent of SARS-CoV-2 infections were responsible for eighty percent of all transmission events in Hong Kong. Contact-tracing during an epidemic helps identify people who have likely come into contact with an infected individual or been to a known contagious location (such as a hospital), and further action such as isolation can be carried out. Super-spreaders are also an essential factor in computer modelling of epidemics. Fujie & Odagaki (2007) show that for an accurate computer simulation of the 2003 SARS-CoV outbreak, a model involving SSEs was necessary. Therefore – although super-spreaders are currently only categorized retrospectively – if it were hypothetically possible that super-spreaders could be proactively identified and isolated from the general population, it would follow that the frequency of SSEs would decrease and spread of the disease in a community could be greatly controlled. To do so, G. Wong et al. (2015) suggests that further study can be done to look for similarities in the patient records of known super- spreaders, such as co-infection or, in the case of MERS-CoV, shared mutations in the carried viral load. Cave (2020), however, argues that too much emphasis on conducting research on super-spreaders and SSEs during an outbreak, specifically the 2020 SARS-CoV-2 outbreak, may not be productive. She argues that during the 2020 SARS-CoV- 2 outbreak, the term ‘super - spreader’ has been loosely used by the media, is heavily attributed with moral blame and stigmatizes people who fit this criteria, and so investigation into super-spreaders which requires disclosure of patient information may be less likely to gain public support or understanding; other investigations could and should be prioritized. Nonetheless, Cave (2020) also recognizes that, if the super-spreading tendencies of the virus are understood, control measures such as better isolation or potential targeted vaccination could be incorporated into exit strategies from imposed lockdown in the US. To conclude, super-spreaders are a minority of individuals who are infected with an infectious pathogen and may infect a disproportionately larger amount of people than other infected individuals during super-spreading events. This may be the result of a combination of (a) behavioural and environmental factors, as evident from the case studies taken from the 2003 SARS-CoV outbreak in Hong Kong; (b) biological factors, as seen from the ‘cloud babies’ phenomenon and related studies. Super-spreading events greatly contribute to the spread of a disease within a community. If the nature of super-spreaders could be better understood, and if super-spreaders could somehow be proactively identified, it is likely the incidence of super-spreading events would be lowered and therefore spread of an infectious disease could be better controlled.
9 Wong et al. 2015.
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