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Table 2 Country co-variates data and sources

From: The relative effects of non-pharmaceutical interventions on wave one Covid-19 mortality: natural experiment in 130 countries


Reason for inclusion


Population density (people per sq. km)

As an infectious disease, higher density of population is likely to aid spread

% Population aged 65+

Older persons more vulnerable to adverse effects of infection

% Population male

Adverse effect of infection might vary by sex

Life expectancy at birth (years)

To adjust for relative baseline health prior to pandemic

Hospital beds (per 1000 people)

To adjust for relative hospital capacity prior to pandemic

Physicians (per 1000 people)

To adjust for relative workforce capacity prior to pandemic

GDP PPP (current international $)

Gross Domestic Product (at Purchasing Power Parity), comparable measure of country wealth and relative average living standard. To adjust for relative deprivation across countries

Manufacturing, value added (%GDP)

Healthcare treatment responses to the pandemic required scale-up of various equipment (e.g. ventilators, testing equipment, and personal protective equipment), globally. Extent of manufacturing base might conceivably have changed how a country was able to respond to changes in demand internally

Health expenditure (%GDP)

To adjust for relative importance given to health budgets prior to pandemic

International tourism, number of arrivals

The virus originated in Wuhan, China. Infectious disease spread from an external source (for all other countries) will conceivably vary by extent of international movement

Governance (Voice and Accountability)

Different governance structures might impact when and how policies were introduced, and how strictly they were adhered to. We use a measure which captures the extent to which a country’s citizens are able to select their government, freedom of expression, association and media, i.e. extent of democracy


The virus originated in the East Asia & Pacific region (Wuhan, China), so region might affect relative timing of virus arrival and any associated technological/virus evolution changes over time

Testing policy (h2)

With Covid-19 testing policy closely tied to attribution of Covid-19 deaths, testing policies will be inextricably linked to the outcome, i.e. more testing will offer more opportunity to attribute a death to Covid-19. We control for this difference by controlling for the extent of testing policy in a given country at a given time

Coding: 0 - No testing policy; 1 - Only those who both (a) have symptoms AND (b) meet specific criteria (e.g. key workers, admitted to hospital, came into contact with a known case, returned from overseas); 2 - Testing of anyone showing COVID-19 symptoms; 3 - Open public testing (eg “drive through” testing available to asymptomatic people)

Contact tracing (h3)

As above, contact tracing is closely linked and reliant on testing policy/capacity. We additionally control for the extent of contact tracing policy in a given country at a given time

Coding: 0 - No contact tracing; 1 - Limited contact tracing - not done for all cases; 2 - Comprehensive contact tracing – done for all cases.