The control vector includes country size, the log of population ( _POPj_ ); a measure of geographic distance to global markets, the log of market penetration ( _MPj_ ), computed as a distance ( _dij_ ) weighted measure of other countries’ GDP ( _GDPi_ ), i.e. _MPj_ = Σ i( _GDPi/dij_ ); and a measure of government effectiveness ( _GEj_ ). Both equations also include (i) the share of imports of medical goods in country _j_ ’s total imports ( _Mshj)_ ; (ii) country _j_ ’s standardized revealed comparative advantage index ( _RCAj_ ) for medical goods;<sup>13</sup> and (iii) the (log of) simple average applied tariff rate [ _ln(1+Tarj_ )] in country _j_ on medical goods.

Large, populous countries are likely to have market power, which in turn may induce governments to use trade policy to affect their terms of trade. Government effectiveness is directly correlated with per capita income. A more effective government is more likely to adapt procurement processes to source needed medical supplies, thereby reducing the incentive to change trade policy. The import share, RCA and import tariff variables proxy for political economy forces that shape pre-crisis trade policy and can be expected to influence the duration of crisis trade measures.<sup>14</sup> Higher import dependence is suggestive of a pro-liberalization domestic political economy. Conversely, high levels of import restrictions suggest a country has industrial development goals. Such countries may relax import barriers temporarily to improve access to essential commodities but are more likely to reimpose import barriers more rapidly to support local production, reflecting prevailing industrial policy objectives. An RCA > 1 for exports of medical products implies supply-side capacity that may induce governments to remove export controls more rapidly if a decision is taken to temporarily restrict exports in response to the pandemic spike in demand.

We also control for the number of COVID-19 cases ( _Covid_casesj_ ) and the number of related deaths ( _Covid_deathsj_ ) as of 22 July 2020. We do this because the number of cases and deaths may affect the likelihood of removing (retaining) trade policy instruments, with greater case numbers potentially associated with more export restrictions, keeping them on longer and/or deeper liberalization of imports of essential supplies. We do not use number of cases/deaths for the early months of the pandemic because in most countries case numbers and deaths were low in the initial period – February-March – when most of trade measures were put in place by those countries that decided to do so.

The dependent variable in all equations is characterized by over-dispersion, which biases log linear OLS estimation. Given the scale-dependence of the negative binomial pseudo-maximum likelihood estimator, we estimate the equations using the Poisson- pseudo-maximum likelihood estimator (PPML) (Santos Silva and Tenreyro, 2006). Given that our interest is in trade policy measures imposed in response to COVID-19 in the first half of 2020 and all the explanatory variables pertain to 2017-2018 (see Section 5 below), endogeneity emanating from reverse causality is unlikely to be a concern in estimating equations (1) and (2). There could however be omitted variable biases, especially given that we cannot include any fixed effects. We therefore refrain from drawing any inferences about causality in the presentation of our results.

# **5. Data sources and descriptive statistics**

The procurement variables used as explanatory variables in the empirical analysis are sourced from the World Bank Doing Business Contracting with the Government indicator and pertain

> 13 The RCA is defined as the ratio <mark>of country</mark> _<mark>j</mark>_ <mark>exports of product</mark> _<mark>i</mark>_ <mark>to its total exports of all products divided by the same ratio for the world. If the RCA</mark> j _i_ <mark>> 1 a country is said to have a revealed comparative advantage in</mark> _<mark>i</mark>_ <mark>.</mark> 14 Leibovici and Santacreu (2020) analyze the potential role of net importer and net exporter status as a potential driver of trade policy activism in a pandemic.

8