Figure 3. Household Secondary Attack Rates (SARs) by Index Case Vaccination Status.

All contacts are included regardless of vaccination status. For Harris et al,⁴⁸ most of the vaccinated index cases (93%) had received only the first dose of vaccine and SARs were not disaggregated by dose. Point sizes (squares) are an inverse function of the precision of the estimates, and bars correspond to 95% CIs. Diamonds represent summary SAR estimates with corresponding 95% CIs. Heterogeneity indexes are as follows: Alpha (unvaccinated: I² = 94.6%; fully vaccinated: I² = 52.7%), Delta (unvaccinated: I² = 99.1%; partially vaccinated: I² = 91.7%; fully vaccinated: I² = 98.6%), and Omicron (unvaccinated: I² = 93.5%; partially vaccinated: I² = 70.5%; fully vaccinated: I² = 0.4%; booster vaccinated: I² = 78.5%).