SARS-CoV-2 Superspreading Events Database

  • what the location of the event was
  • when the event occurred
  • how many people were infected directly and/or indirectly
  • what kind of setting the event took place in
  • what kind of activity took place
  • whether the event took place indoors or outdoors
  • whether the event occurred during flu season in that location
  • at the same venue during a short period of time (e.g. at a party)
  • at the same venue during an extended period of time (e.g. in a nursing home or prison over the course of several days or weeks)
  • at different venues visited by the same superspreader(s)(e.g. an infectious person going on a pub crawl)

Database

Click here to go to the database. Please read the Notes sheet for more information about the database and its limitations.

link to database

Bubble Map with Animated Timeline

Click here to go to the SSE bubble map. Zoom in and click on a bubble to see more information about an SSE.

bubble map

Preliminary Results

  • Nearly all SSEs in the database took place indoors: the exceptions are SSEs that took place in settings with both indoor and outdoor elements and where it is not clear whether transmission occurred indoors or outdoors
  • The vast majority of SSE transmissions took place in settings where people were essentially confined together for a prolonged period (for example, nursing homes, prisons, cruise ships, worker housing)
  • A feature of these settings is that it is typically outsiders rather than the people who live or work in them (or their relatives) who have control over the circumstances in which they work or live (nursing home residents, hospital patients or inmates typically have little control in terms of precautions they can take)
  • The great majority of SSEs happened during flu season in that location
  • Food processing plants where temperatures are kept very low (meat, dairy, frozen foods) seem particularly vulnerable to SSEs compared to other types of factories and plants where very few SSEs occurred
  1. If transmission is primarily through large droplets that don’t travel farther than 6 feet and that fall to the ground almost immediately, we shouldn’t expect superspreading events to be so much more common indoors than outdoors. The behavior of a large droplet is not meaningfully different in an outdoor vs. an indoor setting. It will just fall to the ground almost instantly and not travel farther than 6 feet. Aerosols, on the other hand, are smaller droplets that linger in the air and can travel farther than 6 feet. Aerosols are diluted much faster outdoors than indoors. So the concentration of infectious aerosols in the air people breathe will be much lower outdoors than it is indoors. As a result, superspreading should be much less likely outdoors than indoors. And that is what we see.
  2. Moreover, at a superspreading event one person (or a small number of people) infects dozens or more others. If transmission happens through large droplets it means that person has to be in close contact with each of those other people and talk, sing, shout, laugh or breathe in their direction. In many situations that seems less likely than that an infected person gradually increases the concentration of infectious aerosols in the air in a poorly ventilated space. The risk will still be highest for people in close contact with the index case because the concentration of infectious aerosols is highest directly in front of the person (similar to standing close to a smoker) but people can become infected at a greater distance as well due to the increased concentration of infectious aerosols in the air they breathe.

Limitations

When assessing these conclusions it is important to keep in mind that the database has some severe limitations. For example, in response to the pandemic societies have taken all sorts of measures to try to contain the virus. This includes the closing of various types of settings , such as restaurants, schools and offices etc. As a result, these settings were then no longer able to give rise to superspreading events. which then were no longer able to give rise to any superspreading events. As a result, certain types of high-risk settings could be significantly underrepresented in the database in the sense that superspreading would have occurred there more frequently if they had been open. To take an obvious example, from the fact that there are no indoor concerts in the database it does not follow that indoor concerts do not pose a serious risk.

  • look for images of the venue online
  • try to find detailed descriptions of the event
  • check what the weather was like in that period (eg it is unlikely that a family dinner in Wuhan in January took place outdoors)
  • People may be more likely to remember or mention certain types of settings than other types
  • People who are more likely to have been in certain types of settings may be more (or less) easily traceable by contact tracers, or more (or less) willing to be interviewed by them
  • In institutional settings such as nursing homes, prisons, hospitals and meat processing plants there will typically be more frequent, systematic & comprehensive testing (especially once one or more people have shown symptoms or tested positive) than in other types of settings such as bars or parties.
  1. An error during the testing & analysis (including contamination issues in a lab). This is rare.
  2. The use of high cycle thresholds in PCR testing causes tests to detect insignificant amounts of virus that are not reliable indicators of recent SARS-CoV-2 infections,which may create an inflated impression of the number of current infections in a community, as this New York Times article explains:

Incomplete and Imperfect

Note that while the goal for the database is to eventually include all SSEs found by researchers and authorities, currently that project is far from completion. Many more SSEs than just these 1,500+ have taken place.

Feedback and Help

Any help (corrections, additions, suggestions) would be much appreciated. Send your information to info@superspreadingdatabase.com or add them via the Google Form on this page. Assistance with improving the visualization (for example, to make it look more like this) is also welcome.

How to cite the database

Swinkels, K. (2020). SARS-CoV-2 Superspreading Events Around the World [Google Sheet]. Retrieved from https://docs.google.com/spreadsheets/d/1c9jwMyT1lw2P0d6SDTno6nHLGMtpheO9xJyGHgdBoco/edit?usp=sharing

References

A substantial number of SSEs in this database come from the following sources:

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