highly significantp < 0.001
After comparing the patients with mild and moderate COVID-19 at a ratio 1:1, the average ± standard deviation (SD) HEI-2015 for patients with mild COVID-19 was 55.6 ± 2.8, whereas the average HEI-2015 in patients with moderate COVID-19 was 39.7 ± 9.3 ( p < 0.001, highly significant), so the decision was made for the final sample size of 30 subjects per group (a total of 60 participants), we opted to examine 20 participants per group, compensated by 15% for the use of nonparametric tests, and compensated by 30% for suspected losses in order to be able to reject the null hypothesis, that the population mean HEI-2015 values of the patients with mild and moderate COVID-19 are equal with a probability (power) of 0.999.