COVID-19: The 80-20 Law & Superspreading

By Shlomo Maital

   Some 124 years ago, an Italian economist, Vilfredo Pareto, showed that about 80% of the land in Italy was owned by 20% of the population. Since then management consultants and other experts have extended this Pareto Law, 80-20, to all realms of our lives:

  • roughly 20% of the exercises and habits have 80% of the impact
  • by fixing the top 20% of the most-reported bugs, 80% of the related errors and crashes in a given system are eliminated
  • 80% of crimes are committed by 20% of criminals

       Now comes “80-20” in the context of COVID-19.

     Today’s New York Times has an article by two infectious disease researchers, Dillon C. Adam and Benjamin Cowling, “Just stop the superspreading”. For Hong Kong, they found that “superspreading [a small number of virus spreaders infecting a large number of people] overwhelmingly contributed to the transmission of SARS-Cov2 in the city overall… In our study just 20 per cent of cases all of them involving social gatherings accounted for an astonishing 80 per cent of transmissions.” And, they add, another 10 per cent of cases accounted for the remaining 20 per cent of transmissions. In other words, 30 per cent of cases account for ALL of the transmissions!

     Does this apply only to Hong Kong, a very densely populated city? No. Many other studies confirm the 80-20 principle.

Bottom line?

     The researchers note, “Forget about maintaining – or, if infections resurge, resuming – sweeping measures designed to stem the virus’s spread in all forms. Just focus on stopping the superspreading.”   Stop that 20 per cent, and you stop 80 per cent of the new cases.

   But how? 

   In Israel, the premier football league has resume play. Two teams played in the Bloomfield Stadium; spectators were banned and the stands were empty. But after their team HaPoel Tel Aviv won 2-0, thousands of fans gathered outside the stadium, clustered together, and celebrated the win. Police were helpless.