Fig 1.
Variation of the number of secondary infections per 10,000 students according to the size of bubble groups.
Number of secondary cases obtained from the numerical simulations by varying values of R* and numbers of scholars forming the bubble groups after the detection of the first infected student. Simulations done keeping A14 = 250 cases per 100,000 inhabitants, and the total number of students fixed to 1,436,680 (A14 = Cumulative incidence over 14 days).
Fig 2.
Variation of the number of secondary infections per 10,000 students according to the days of quarantine.
Number of secondary cases obtained from the numerical simulations tuning the values of R* and varying the number of quarantine days after the detection of the first infected individual. Simulations done keeping A14 = 250 cases per 105 inhabitants, and the total number of groups of 20 students fixed to 72,000 and therefore the total number of students fixed to 1,440,000.
Fig 3.
Evolution of the number of confined groups in schools in Catalonia compared with the estimations based on the incidence.
Temporal evolution of the confined groups in Catalonia from 1st October to 31st December 2020 and the corresponding 7-days moving average (red solid line). Comparison with the estimations proportional to the 7-days moving average of the 10-day cumulative incidence in Catalonia using (1-η) = 0.35 (A10, green solid line), and with the same curve with a 2-day shift (green dashed line) to highlight the delay between the A10 and the actual dynamics of the number of confined groups.
Fig 4.
Estimation of the probability of contagion from epidemiological data.
Fraction of groups going into quarantine with a number N of secondary infected (SI) students by COVID-19 for primary (A) and secondary (B) schools. Bars of the data are shown in comparison with the fraction of groups with a number N of cases of COVID-19 obtained from the numerical simulations (coloured lines) (A and B). Note that y-axis is plotted in a logarithmic scale. Mean square displacement (MSD) of the fractions obtained from the simulations with different values of R* with the data obtained from Primary (C) and Secondary (D) schools. Vertical dashed lines correspond to the reproductive number calculated from the data obtained from Primary and Secondary schools. Dependence of the fraction of a single case (E) and two cases (F) on the probability of contagion R* (solid line with circles) in comparison with the fraction obtained in the schools. Red and green dashed lines correspond, respectively, to the fraction in primary and secondary schools of single infected child (E) and two infected students (F). Simulations are done keeping A14 = 250 cases per 105 inhabitants, and the total number of groups of 20 students fixed to 72000. Data from primary and secondary schools are shown in S1 Table, obtained from the Government of Catalonia.
Fig 5.
Heatmap of the ratio between homogenised monthly cumulative incidence by age group and that of Catalunya, excluding data from nursing homes.
Colour scale indicates homogenised incidence below the mean (green) and above the mean (red), as shown by the legend. December has been split between working period (Dec-work) and Christmas holidays (Dec-hol).