Moore D A, Hopkins R S
Division of Field Services, Centers for Disease Control, Atlanta, GA.
Am J Epidemiol. 1991 Jun 1;133(11):1161-7. doi: 10.1093/oxfordjournals.aje.a115828.
Two Ohio schools experienced an outbreak of over 200 cases of chickenpox during the period from October 5 to December 21, 1988, despite adherence to the 1986 American Academy of Pediatrics' recommendation that children be excluded from school for 1 week or until all lesions have crusted. In grades kindergarten through four, the attack rate for susceptibles was 51% (167/329). With the use of person-time analysis, classmates of a child with chickenpox in grades kindergarten through four were 3.6 times more likely to become a case 12-17 days (the range of one incubation period) after the last day the child with subsequent chickenpox was in class than at any other time during the 2.5-month study period (95% confidence interval (Cl) 2.4-5.4). This was even more pronounced during the first half of the outbreak (relative risk (RR), 10.8; 95% Cl 4.4-26.5). Cases were not more likely to aggregate 12-17 days after a child returned to school after having chickenpox (RR, 0.9; 95% Cl 0.5-1.5). No cases occurred in classmates 12-17 days after the 15 children absent less than 5 days returned to class. Because substantial chickenpox transmission may occur before rash onset, exclusion practices may have a limited effect on outbreak control and increase the indirect costs associated with chickenpox.
1988年10月5日至12月21日期间，俄亥俄州的两所学校爆发了200多例水痘疫情，尽管学校遵循了1986年美国儿科学会的建议，即让患病儿童停课1周或直至所有皮疹结痂。在幼儿园至四年级，易感儿童的发病率为51%（167/329）。通过人时分析发现，幼儿园至四年级患水痘儿童的同班同学，在该患病儿童最后一天上课后的12 - 17天（一个潜伏期范围）内发病的可能性是2.5个月研究期内其他任何时间的3.6倍（95%置信区间（Cl）2.4 - 5.4）。在疫情爆发的前半期，这种情况更为明显（相对风险（RR）为10.8；95% Cl 4.4 - 26.5）。水痘患儿返校后12 - 17天内，同班同学发病的可能性并未增加（RR，0.9；95% Cl 0.5 - 1.5）。15名缺课少于5天的儿童返校后12 - 17天内，其同班同学未出现病例。由于水痘在出疹前可能大量传播，因此隔离措施对疫情控制的效果可能有限，且会增加与水痘相关的间接成本。
