Relationship between index cases and secondary cases with household transmission.

Abstract

<p>Relationship of household transmission (A) among children and (B) among children and adults. Red circles represent index cases, blue triangles represent secondary cases, and arrows show the direction of transmission. The letters represent affiliations; A: school A; B: school B; C: preschool C; D: preschool D; E: preschool E; F: preschool F; G: children at home; H: adults.</p