High infection rates with only a limited number of individuals traced back, characterizes the spread of COVID-19 through superspreader events. Lukas Zenk and Gerald Steiner from the Department for Knowledge and Communication Management and their colleagues have published a paper analyzing which biological and social factors lead to superspreading behavior, and how to deal with the resulting uncertainties.
Austria is in the middle of the second COVID-19 wave and the whole world is called upon to understand and manage potential systemic risks of the pandemic. The rapid and unpredictable spread of SARS-CoV-2 is particularly challenging. One way to monitor the spread is the meanwhile known reproduction factor, which gives the average number of infections per person. In the case of the corona virus, however, this number is unevenly distributed. The current estimation is that fewer than 20 per cent of infectious persons have passed on the virus causing about 80 per cent of further infections. The remaining 80 per cent of infectious persons are contaminating only about 20 per cent of infected persons. The so-called dispersion parameter K indicates this circumstance. A high value, such as for the influenza virus, means that infected persons infect about the same number of other persons. A low parameter, as in the case of the corona virus, translates into the phenomenon of superspreading - a small number of people infect many others.
The phenomenon of distributing superspreading
On the one hand, superspreading can simplify contact tracing, for example, since a number of infections can be traced back to a single source - the "superspreader". On the other hand, it also holds risks: Even if it seems that an infection is under control (as for instance was the case in Austria and large parts of Europe during the COVID-19 pandemic in the summer), the phenomenon of superspreading can contribute to a very rapid resurgence of infection. A few superspreader or superspreader events potentially lead to more large clusters in a short time.
Preparing for the unpredictable
Superspreading is difficult to predict from today's perspective and can quickly lead to medical shortages and socio-economic emergencies. Under such uncertain and unpredictable circumstances emerging, organizations and societies worldwide are called upon to develop appropriate strategies and intervention portfolios to contain the virus' spread accordingly. Improvements in testing strategies and broad-based information to the population can be part of these strategies. Raising awareness of the superspreading phenomenon helps to understand a sudden COVID-19 outbreak at any time, even with relatively low infection rates. To act quickly, even to improvise possibly is necessary, as predictive statements in this context are difficult to make.
Understanding factors enhancing superspreading
Assistant Professor Lukas Zenk and Dean Gerald Steiner, both from the Department for Knowledge and Communication Management at Danube University Krems, and Professor Eva Schernhammer, Channing Division of Network Medicine, Harvard Medical School, Boston, and colleagues shed light on most of the different facets of superspreading in their work. Using simple examples, they explain which biological and social factors enhance surperspreading.
Among others, biological factors include an inherently higher viral load, and spitting while talking, create a so-called "corona cloud" surrounding a person. However, the individual network of social contacts are also a decisive factor for spreading. The number of contacts people have with each other is also irregularly represented, similar to a low dispersion factor. A handful of people have contact with many people, whereas many people tend to meet with few other people. One reason is owed to the fact of social dynamics - people with many contacts get even more contacts - and another is the occupation, such as health care professions. People with both corresponding biological and social factors risk to become a superspreader. If these people attend larger gatherings without appropriate protective measures, this results in potentially superspreading events.
The paper also deals with measures to minimize superspreading. Since people do not know whether they are spreading viruses, general precautions must be taken. Avoiding loud talking and singing in poorly aired rooms as well as the well-known keeping distance rules and suitable face masks are already effective. Reducing the amount of alcohol consumed in groups is also an effective behavioral adjustment, because some people have an excessive saliva building when drinking, or do not maintain physical distance.
Superspreadings will continue to occur all over the world until the pandemic is contained. People, but also organizations and countries, have to learn to adapt to new circumstances even at short notice, because of the unforeseeable nature of these incidents. Besides long-term plans and strategies, the paper emphasizes the role of improvisation in order to use currently available resources in the best possible way and to remain capable of acting outside of routines at the moment. It is not only crucial due to the current pandemic to acquire these skills, but also helpful for possible future events.