policy of contact tracing and confinement implemented for 70% of reported cases worked well to limit the attack rate, as did general school and workplace closure started after a threshold of infections was reached. These results are in tune with the insights from the historical studies, but confound those from Ferguson _et al._ (2006).<sup>59</sup> It is likely that during a pandemic substantial number of secondary infections may occur in households, where the index cases acquire the disease in community transmission. Wu _et al._ (2006)<sup>27</sup> compare the effect on the overall attack rate of community‐level policies that reduce such within‐ and between‐household transmission. The model used is a ‘stochastic SEIR’ simulation, which lacks a spatial component unlike the other comparative studies. Wu _et al_ . make the claim that rapid spread will make this issue less relevant<sup>47</sup> .

|**_Table 11: Effectiveness o_**<br>**_strategies_** **_in apop. o_**<br>**_f different NPIs/mixed_**|**_f_**<br>**_1 mn._** _(Wu et a_<br>_l_|_. 2_<br>_006)_|
|---|---|---|
|Policy/mixed strategy|.8_, θ_<br>=<br>_R0_=1<br>|30<br>%<br><br>|
||Atta<br>e %<br>ck rat|P<br>*<br>eakQ|
|_No intervention_|74%|0|
|**_Q_:**<br>_u_<br>_antine_‐<br> _Q ar_<br>segregation within their own homes of a complying<br>household contacts ofsuspected case|49%|9.6%|
|**_QI_**:<br>_solation_(_I_ c<br> _Q_+_I_<br>, omplying symptomatic individuals are removed<br>fromtheir household to a separatefacility)|43%|7.1%|
|**_QA_**: +<br>_v_<br>embers<br>t<br>)<br>_Q_ _Anti irals_(_A_, complying symptomatic household m<br>a e<br>fantiviraland s m<br>k 2doses o<br>y<br>ptom‐freemembers take1|44%|0<br>.5%<sup>**</sup>|
|**_QIA_**:_Q_+_I_+_A_forallcomplyingindividuals, as appropriate|40%|6.2%|
|**_QIAC_**:_Q_+_I_+_A_+_Contact tracing_(_C_, symptomatic and isolated<br>individuals name people they may have infected, and those are<br>notified and asked to take precautionarymeasures _Q_ and _A_)|34%|≈13.5%|

* Peak % of the population living in conditions of household quarantine<sup>**</sup> 3.9 oses per person in the population d

The authors find a significant role in mitigation for NPIs at moderate levels of compliance even without TAP. At similar compliance levels in Ferguson _et al._ (2006), quarantine had lower relative effectiveness (policy **_12_** , Table 8). Antiviral prophylaxis reduces the number of people in quarantine, thus reducing the social and ethical burden. However, for the baseline simulation (Table 11) at 50% compliance for the policies and _R0_ =1.8, the antiviral stockpile required is quite large. The proportion of presymptomatic or asymptomatic transmission, _θ_ , was assumed to be 30% in the baseline simulation<sup>60</sup> .

The major contribution of their study is highlighting aspects of feasibility for community‐level policies. First, they explicitly compare their assumptions to those in the studies by Germann _et al._ and Ferguson _et al._ (2006). While Wu _et al._ assume 67% of cases will show symptoms and be reported (vs. 50% in Ferguson _et al._ and 60% in Germann _et al._ ), they conservatively assume a 50% compliance with subsequent policy interventions. The other two studies mostly model higher levels of implementation with their reported cases. Wu _et al._ rule out contact tracing as infeasible in large networks (even if effective as **_QIAC_** ), though Germann _et al._ allow that TAP for 60‐100% of contacts outside the household will be feasible in early stages of a US epidemic. Second, Wu _et al._ consider compliance more carefully. For policies that confer immediate benefits to the individual ( **_QA_** , as well as **_QI_** since guaranteed access to antiviral is assumed in case isolation) compliance may be higher, while lower for quarantine policy. Compliance with isolation would be affected by the characteristics of the index case and household structure. Third, with the peak quarantine rate as an outcome, the authors discuss feasibility in terms of the demands various policies place on authorities to ensure essential supplies for the restricted population. Finally, they 29