Incidence of infection
Space of contact (sq. meters) No. tested Infected (%)
  -24 108 18(16.7)
25-49 81 19(23.5)
  50-99 151 28(18.5)
  100-399 191 18(9.4)
  400- 60 2(3.3)
Total   591 85(14.4)
P of trend of linear trend of proportion <0.01, Unknown space of contact; 22 cases
Table 5: Incidence of infection according to area of space where contacts occurred.