antivirals for a future pandemic strain may vary from the known parameters today, and a well‐matched vaccine will only be ready with a lag since the beginning of a global pandemic. Additionally, pharmaceutical policies are resource‐intensive, which implies only certain countries will be able to use them.

The current distribution of global resources indicates that risk‐reduction strategies that emphasize non‐pharmaceutical measures alongside techniques to reduce international spread would be valuable from the perspective of secondary risk countries (the majority of countries). However, modeling of NPIs has shown varying effectiveness according to modeled context and historical evidence from the 1918 pandemic. Globally, NPIs have a role in _mitigation_ at moderate _R0_ and _θ_ , even without antiviral prophylaxis or vaccination in tandem. The timing requirements for NPIs are not more onerous than for drug‐based strategies, but they may have significant societal costs. The NPI effectiveness seen in the studies for S.E. Asia is higher than in studies for the U.S., possibly due to model‐related factors. The early use of NPI intervention, limited seeding, and the lack of reintroductions in the S.E. Asian models may explain the observed difference. In contrast, for U.S.‐specific models, given likely delays in starting interventions, reintroduction risk alongside multiple infection seeds, a persistent decline in susceptibility and infectiousness through pre‐ vaccination with a pre‐pandemic vaccine and/or antiviral prophylaxis is preferred.

However, pharmaceutical policies are resource and capacity intensive, and may be overkill in conditions of moderate _R0_ if a strategy of cooperative IATRs mixed with border control/airport quarantine in secondary risk countries is probable and effective in reducing infection seeds. Also, if containment in frontline countries following the WHO Interim Protocol<sup>1</sup> is progressively successful, and more countries cooperate as seen in a recent study<sup>80</sup> to share antiviral stockpiles, the reintroduction risk globally would fall. In this situation, for countries at secondary risk the policy objective will resemble early containment. This implies that the choice of stringent, layered NPIs at airports and reactive NPIs in communities could minimize the attack rate in secondary risk countries, and be less costly from a social perspective. Backward induction from this insight implies that if international cooperation can be ensured, the pharmaceutical‐focused strategy in certain countries should be recalculated.

In situations of higher infectivity ( _R0_ ), the primary benefit of NPIs will be to delay peak transmission such that a well‐matched vaccination policy becomes viable. However, any such vaccination policy that succeeds internationally will require a plan for the distribution of antigen stocks to resource‐poor settings to mitigate the risk of future outbreaks as well as to meet current ethical standards. Early estimation of the infectiousness of the pandemic strain and timely and complete sharing of viral data will be essential in setting international priorities and control strategies.

**Note:** For specifics on the particular dose and distribution choices for vaccination strategies, see the main text. Also see the main text for details on ethical considerations of particular policies as well as international cooperation on viral data; as well as cost‐effectiveness studies of particular control strategies.

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