Table 2

Summary of reported secondary cases from 1 January 2015 to 30 April 2020, in Zanzibar

201520162017201820192020*
No of household members tested during index case investigation11 601†8479763810 78214 9638511
Median age (years) of investigated index cases15 (IQR: 7–25)16 (IQR: 8–26)16 (IQR: 7–25)18 (IQR: 8–28)17 (IQR: 8–26)
Fraction of index cases who are male (%)49.741.643.747.448.553.0
No of positive investigated people (secondary cases) (%)591† (5.1%)365 (4.3%)319 (4.2%)445 (4.1%)544 (3.6%)267 (3.1%)
No of positive investigated people (secondary cases) performed from January to April (%)169 (6.7%)167 (4.9%)74 (4.7%)164 (4.8%)177 (5.1%)267 (3.7%)
Probability to find a secondary case during investigation (95% CI)0.048† (0.045 to 0.052)0.041 (0.037 to 0.045)0.040 (0.036 to 0.044)0.040 (0.036 to 0.043)0.035 (0.032 to 0.038)0.030 (0.027 to 0.034)
  • *Time period 1 January to 30 April.

  • †Data available from 1 January to 16 September.