Selecting and harmonising metrics of global health security
The GHS Index conceptualises a health security capacity as a state’s ability or potential to carry out a discrete public health or healthcare function necessary to prevent, detect or respond to acute infectious disease threats, be they naturally occurring, accidental or deliberate. Featured indicators in the GHS Index are intended to aid users in monitoring and measuring the investments and processes that enable states to build, sustain and implement these capacities. The GHS Index does not, however, purport to forecast health outcomes or impacts resulting from country investments in strengthening health security capacities.
Some have asserted that the indicators selected for inclusion in the GHS Index may reflect a systematic bias towards higher-income countries.17 Given that national gross domestic product (GDP) and GDP per capita correlate only weakly with overall GHS Index scores—as evidenced by Pearson’s r values of 0.37 and 0.45, respectively—this seems unlikely. Fidler writes, however, that global health security ‘ultimately depends on the quality of national public health systems.’18 As such, we have taken care to include indicators in the GHS Index that measure material determinants of country-level health security capacities, such as preparedness spending—which do correlate strongly with national income.
However, the GHS Index also incorporates social, political, technical and environmental determinants of health security, which do not necessarily correlate directly with national income level alone. On measures of healthcare access (Indicator 4.3), for example, the first-ranking, second-ranking and fifth-ranking countries were Thailand (upper-middle-income), Georgia (lower-middle-income) and Nigeria (lower-middle-income), respectively. Other factors, such as strength of laboratory systems (Indicator 2.1) and international commitments (Indicator 5.3), also correlate more strongly with overall GHS Index scores (r=0.80 and 0.76, respectively) than with overall GDP (r=0.25 and 0.23, respectively). To further prevent potential confounding by income level, users might consider comparing overall, indicator and sub-indicator-level scores across countries within a given income group and adjusting model weights to align more closely with the specific health priorities of a given country or region.
Moreover, indicators were developed with the aim of ensuring the GHS Index’s integration with existing global health security assessment tools and frameworks such as the GHSA, the JEE and the IHR Monitoring and Evaluation Framework, as well as the NAPHS development process, as Razavi et al recommend. However, other scholars have highlighted a need for global health security metrics that do not simply mirror global patterns of wealth distribution, and that more accurately capture health system functionality and performance rather than capacity alone.19 20 Though the GHS Index does extrapolate beyond the metrics featured in the aforementioned frameworks to encompass novel measures of risk, vulnerability and health system readiness, its primary goals remain (1) supporting and enhancing existing health security-strengthening mechanisms in a comprehensive, accessible format; and (2) motivating decision makers in all countries to make needed investments in epidemic and pandemic preparedness.
Thus, while more meaningful metrics of health security capacity are certainly warranted and merit deeper consideration by the international community, we contend that developing these metrics supersedes the original intention of the GHS Index to leverage existing, publicly available data. However, as we learn from COVID-19, we do plan to revise the GHS Index Framework to include new, more targeted measures of pandemic readiness (see the Next steps section).