Expected impact of COVID-19 outbreak in a major metropolitan area in Brazil

Tarcisio M Rocha Filho; Fabiana S. Ganem dos Santos; Victor B Gomes; Thiago A.H. Rocha; Julio H.R. Croda; Walter M Ramalho; Wildo N Araujo

for the i-the age group, with β i,j the transmission matrix, which is estimated as follows. We first 79 consider the contact matrix C i,j as given by the average number of physical contacts per time 80 unit of and individual of age group i with any individual of group j. Since the present available 81 information does not allow to determine a probability of contagion for each specific group, we 82 consider the transmission probability per contact P c being the same for all infected individuals. 83 We thus have that β i,j = P c C i,j . There are some studies determining the contact matrix for 84 different regions in the world, but none for any Brazilian city. So we considered the study in 85 Ref [29] where the contact matrix was determined from field studies for eight different European 86 countries. Our working hypothesis was that these results can reasonably be transposed for the 87 metropolitan area of São Paulo. Since contact matrices for these different countries do not vary 88 significantly, we take their average for C i,j , and the contact matrix resulting from this procedure 89 is shown as a heat map in Fig 1. The transmission probability is then obtained by adjusting the 90 value of the basic reproduction number from the relation