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Fear for COVID-19

He didn’t feel like getting up. The pandemic had exploded in north-eastern France and Spain. Europe had now overtaken China. Welmoed felt an infection in the ear yesterday. In terms of chemo resilience via telephone photographic consultation to the hospital. This was converted to accommodate COVID impact. Special guidance of patients and the like. She knows the hospital, but still. Disappears, alone, in the emergency room. Meanwhile, he had time in the car to count his blessings. Which resulted in semi-rational speculation about what we can do ourselves to limit the risk of contamination. He gets key figures from Worldometer. As of March 18, 2020, 80,928 COVID-19 cases were reported in China, of which 70,420 had recovered and 3,245 died. 2,274 patients are in critical condition. The situation was different in the Netherlands: 2,051 noted, 2 recovered, 58 deceased and 45 in critical condition. He was unhappy with the combination of these numbers and his ignorance and, given the epidemic’s dynamics, the expectation he and his family would be affected sooner or later anyway. Could he do something about this ignorance in a way that gave him a more active role in averting or postponing that moment? To not become discouraged, depressed and depressing to the others?

Worldometer states somewhere “The attack rate or transmissibility (how rapidly the disease spreads) of a virus is indicated by its reproductive number (Ro, pronounced R-nought or r-zero), which represents the average number of people to which a single infected person will transmit the virus. WHO estimated (on Jan. 23) Ro to be between 1.4 and 2.5.”

The repro number for Ro is an indication, an average. That would be unsatisfactory even if it were precise and reliable. For example when it would have been more scientific and more definitive established on


there is no suggestion how an individual contribution could help bring it down, from an individual nor collective point of view.

The formula does allow him to defend the statement that after the incubation period has elapsed, the infections will have doubled and that, if the incubation period is 5 days, the number of infected persons has increased after each generation with Ro_{covid19} times the difference between the previous and the last-but-one number. To experiment with different incubation times and repro numbers, he translated this recipe into NetLogo. He had it run on his PC with different parameter values ​​- below a printout of 17 generations of five day incubation times with a repro factor of 2.

Figure 1 (algorithm 0)

After 90 days, starting at the end of December and ending on March 18, 2020, these parameter values lead to 262,132 virtual infections instead of the 218,822 registered infections indicated by worldometer. He finds the result astonishing. The algorithm broadly matches what is happening in reality. But does it also provide clues to bend reality? This question unthreads a goal worth investigating further. This is inspiring. Certainly if the results of more small-scale algorithms would help to turn Figure 1 in a targeted manner while restoring rational relations between law, culture, market and technology.