Independent researcher Nora Loreto maintains a  comprehensive database of Covid deaths in Canada. There are three sheets: Deaths in residential care facilities, deaths in workplace outbreaks, deaths among health workers: One striking claim is that by early May at least six and possibly up to ten  of about 700 taxi / limo drivers working out of Toronto Pearson airport had already died after testing positive for Covid. While it is not clear how many of them picked up the virus while on the job, this would be a strikingly high infection fatality rate, even if we were to assume that infection rates among drivers are much higher than in the general population.  Data from the Office for National Statistics for Wales and England confirms that taxi drivers are in one of the highest risk categories: Road transport drivers, including taxi and cab drivers and chauffeurs, had some of the highest rates of death involving COVID-19 for men Of the remaining major occupational groups with high rates

New article in PNAS: Abstract Superspreaders, infected individuals who result in an outsized number of secondary cases, are believed to underlie a significant fraction of total SARS-CoV-2 transmission. Here, we combine empirical observations of SARS-CoV and SARS-CoV-2 transmission and extreme value statistics to show that the distribution of secondary cases is consistent with being fat-tailed, implying that large superspreading events are extremal, yet probable, occurrences. We integrate these results with interaction-based network models of disease transmission and show that superspreading, when it is fat-tailed, leads to pronounced transmission by increasing dispersion. Our findings indicate that large superspreading events should be the targets of interventions that minimize tail exposure. Superspreading has been recognized as an important phenomenon arising from heterogeneity in individual disease transmission patterns (1). The role of superspreading as a significant source of dise

Betsy Ladyzhets who writes the COVID-19 Data Dispatch newsletter did some beautiful interactive Tableau visualizations of the superspreading events in the database: Read more .

Michael Stock at the Probabilis blog did some nice analysis and presentation of the information in the database: Read more .

At a superspreading event one infects many. The inverse would be many infecting one. And that is what seems to have happened in a prison in Vermont. The Wall Street Journal writes : Federal health officials changed the definition of a close contact of a Covid-19 case, after a Vermont prison officer tested positive following several brief encounters with infected inmates. The officer, a 20-year-old man, never was within 6 feet of any of the prisoners for 15 or more consecutive minutes, according to a report on the case by the U.S. Centers for Disease Control and Prevention and the Vermont Department of Health posted Wednesday. After publishing the report online, the CDC altered its definition of a close contact, saying it is now someone who was within 6 feet of an infected person for a total of 15 minutes or more over a 24-hour period. The previous definition was anyone who was within 6 feet of an infected person for at least 15 minutes. “In the end, you just need to inhale e

 In the Superspreading Events database, we try to establish how many people were infected at the event itself , because this helps us to guage the risks involved in that situation.  However, press reports often refer to the total number of cases linked to  a superspreading event.  Linked cases include those in the wider community arising from the superspreading event.  For example, if 20 people were infected at a party, and some of those people infected 30 household members, an epidemiological investigation would conclude that 50 cases were linked to the party.  But in terms of assessing the risks of a setting, there are important differences.   Index and Secondary Cases An  index case  at an event is a person who brings the infection there.  There may be more than one.  Index cases are also known as 'Primary cases'. Secondary cases  are people who became infected in this setting. Tertiary cases  are people who later became infected by secondary cases, eg when they went home o

 From all continents , including Antarctica.