The impact of COVID-19 on recent tendencies towards international isolationism has been much speculated on but remains to be seen. We suggest that valuable evidence can be gleaned from the “Spanish” flu of 1918–20. It is well-known that the world fell into a protectionist spiral following the First World War, but scholars have almost exclusively ignored the impact of the pandemic. We employ a difference-in-differences strategy and find that the flu had a significant impact on trade policy, independent of the war. In our preferred specification, a one standard deviation increase in excess deaths during the outbreak implied 0.022 percentage points higher tariffs subsequently, corresponding to an increase of one third of a standard deviation in tariffs. Health policy should aim to avoid the experience of the interwar period and consider the international macroeconomic impact of measures (not) taken.

人们对 COVID-19 对近期国际孤立主义趋势的影响进行了大量猜测，但仍有待观察。我们建议可以从 1918-20 年的“西班牙”流感中收集有价值的证据。众所周知，第一次世界大战后世界陷入保护主义漩涡，但学者们几乎完全忽视了大流行的影响。我们采用差异化策略，发现流感对贸易政策产生了重大影响，与战争无关。在我们的首选规范中，疫情期间超额死亡人数每增加一个标准差意味着随后关税提高 0.022 个百分点，对应于关税标准差的三分之一增加。