| Subgroupa,b,c,d | n | Spearman’sρ | P value |
|---|---|---|---|
| All countries | 38 | 0.5275 | 0.0007 |
| Countries with testing policy = 1 | 25 | 0.5297 | 0.0065 |
| Countries with testing policy = 2 | 6 | 0.3714 | 0.4685 |
| Countries with border closures = 0 | 7 | 0.6071 | 0.1482 |
| Countries with border closures = 3 | 13 | 0.4622 | 0.1118 |
| Countries with border closures = 4 | 9 | 0.5500 | 0.1250 |
| Countries with young populations | 19 | 0.4952 | 0.0311 |
| Countries with older populations | 19 | 0.1667 | 0.4953 |
| Countries with oldest populations | 10 | 0.0303 | 0.9338 |
| High-income countries | 23 | 0.2490 | 0.2519 |
| Upper-middle income countries | 9 | 0.2176 | 0.5739 |
| Lower-middle income countries | 5 | –0.3591 | 0.5528 |
aTesting policy as ranked by the Oxford COVID-19 Government Response Tracker: 0 = no testing policy; 1 = only those who both a) have symptoms; and b) meet specific criteria (for example, key workers, admitted to hospital, came into contact with a known case, and/or returned from overseas); 2 = testing of anyone showing COVID-19 symptoms; 3 = open public testing (for example, ’drive through’ testing available to asymptomatic people); and Blank = no data. bBorder closure metric measures restrictions on international travel as ranked by the Oxford COVID-19 Government Response Tracker: 0 = no restrictions; 1 = screening arrivals; 2 = quarantine arrivals from some or all regions; 3 = ban arrivals from some regions; 4 = ban on all regions or total border closure; and Blank = no data. cAge of population: young populations = proportion of the population aged ≥65 years is below 50th percentile; older populations = proportion of the population aged ≥65 years is between 50th and 75th percentile; and oldest populations = proportion of the population aged ≥65 years is above the 75th percentile. dOnly subgroups with a minimum of five countries were included, hence low-income countries were excluded from subgroup analyses.