IntroductionThe Global Health Security Index benchmarks countries’ capacities to carry out the functions necessary to prevent, detect and respond to biological threats. The COVID-19 pandemic served as an opportunity to evaluate whether the Index contained the correct array of variables that influence countries’ abilities to respond to these threats; assess additional variables that may influence preparedness; and examine how the impact of preparedness components change during public health crises.MethodsLinear regression models were examined to determine the relationship between excess mortality per capita for the first 500 days of countries’ COVID-19 pandemic and internal Index variables, as well as external variables including social cohesion; island status; perceived corruption; elderly population size; previous epidemic experience; stringency of non-pharmaceutical interventions; and social and political polarisation.ResultsCOVID-19 outcomes were significantly associated with sociodemographic, political and governance variables external to the 2019 Index: social cohesion, reduction in social polarisation and reduced perceptions of corruption were consistently correlated with reduced excess mortality throughout the pandemic. The association of other variables assessed by the Index, like epidemiological workforce robustness, changed over time. Fixed country features, including geographic connectedness, larger elderly population and lack of prior coronavirus outbreak experience were detrimental to COVID-19 outcomes. Finally, there was evidence that countries that lacked certain capacities were able to develop these over the course of the pandemic.ConclusionsAdditional sociodemographic, political and governance variables should be included in future indices to improve their ability to characterise preparedness. Fixed characteristics, while not directly addressable, are useful for establishing countries’ inherent risk profile and can motivate those at greater risk to invest in preparedness. Particular components of preparedness vary in their impact on outcomes over the course of the pandemic, which may inform resource direction during ongoing crises. Future research should seek to further characterise time-dependent impacts as additional COVID-19 outcome data become available.