Which of the following is true of Chicken pox?

(Virus not found in scab) Chicken pox Is an acute highly infectious disease caused by Varicella zoster virus. As a rule, infectious diseases are not communicable during the incubation period, except, measles, chicken pox, whooping cough and hepatitis A, which are common during the later pa of Incubation Period. A painful, vesicular, pustular "dew-drops" like pleomorphic centripetal rash/eruptions in the distribution of one or more sensory nerve roots is characteristic feature (palms and soles usually not affected). The virus can be readily isolated from the vesicular fluid during the first three days of illness. Scabs begin to form 4-7 days after rash appears. The scabs are not infective. The secondary attack rate in household contacts approaches 90%. It is transmitted from person to person by droplet infection and nuclei, and most patients are infected by "face to face" contacts. IP = 14-16 days. Infectivity of chicken pox and hence the duration of isolation for Chicken pox is until all lesions crusted: usually about 6 days after onset of rash from the onset of catarrhal stage.