Table 3b.

Output of the univariate regression on the COVID-19 deaths percentage by region SE = standard error. Significant level at 0.05, (The variables with p-value <0,05 are marked in bold) CI = confidence interval.

Variable	Regression coefficient	SE	P-value	% of variation explained	Effect size (%)	95% CI
Vitamin D UV exposure	−4.77	0.66	<5.0 × 10−4	74.2	−10.3	−13.0	−7.4
PM10	0.03	0.03	2.4 × 10−1	7.5	1.8	−1.3	5.1
RH	0.06	0.05	2.2 × 10−1	8.2	10.5	−6.3	30.4
T	−0.15	0.05	6.8 × 10−3	34.2	−3.6	−6.0	−1.1
Mean age	0.12	0.08	1.6 × 10−1	10.8	12.9	−5.0	34.0
NHR/population %	132.86	25.56	<5.0 × 10−4	60.0	2.1	1.2	2.9
Mortality rate	0.12	0.09	2.1 × 10−1	8.7	3.0	−1.8	8.0
Ischemic heart diseases	−31.35	15.87	6.4 × 10−2	17.8	−3.6	−7.2	0.2
Circulatory system diseases	−17.91	4.59	1.0 × 10−3	45.9	−5.9	−9.0	−2.8
Cerebrovascular diseases	−41.22	14.69	1.2 × 10−2	30.4	−3.4	−5.9	−0.9
Diabetes mellitus	−18.49	4.28	<5.0 × 10−4	51.0	−2.5	−3.7	−1.3

RH = relative humidity.

NHR = nursing home residents.

T= air temperature.