*2.1. Study Design*

A cross-sectional study was carried out in November–December 2020 on a sample of 500 Polish adults aged 60 years or older using computer-assisted telephone interviews. The response rate was 40%. A stratified sampling per the demographic structure of voivodeship was used to obtain a representative sample of the elderly population. Target quotas were set for age and gender strata in each geographical region. The interviewers were properly trained and prepared to ensure the quality and accuracy of the interview. A data collection supervisor supervised all interviews, and a study coordinator randomly evaluated the recordings of the dialogue. The transcripts were not returned to participants for comment and/or correction, nor were repeat interviews carried out. The duration of the interview ranged from 15 to 20 min. Participants provided their consent at the beginning of the interview. No compensation was provided for participating in the study. The study was approved by the Bioethics Committee of Wroclaw Medical University.

#### *2.2. Explanatory Variables*

The questionnaire was designed in a way to provide the most crucial information regarding the respondent's socio-demographic data, economic situation, and general, subjective knowledge about COVID-19. Socio-demographic data included (1) gender (male/female), (2) age (categorized as 60–64; 65–69; 70 and more), (3) place of residence (village; town, less than 20,000 inhabitants; town, between 20,000 to 100,000 inhabitants; town, between 100,000 to 200,000 inhabitants; town, between 200,000 to 400,000 inhabitants; town, more than 400,000 inhabitants), (4) education (primary, vocational, secondary, higher), (5) body mass (kg), (6) body height (cm), and (7) BMI (kg/m2). Patients were also asked for (8) household income per person per month (in Polish currency-PLN: less than 500 PLN; 501–1000 PLN; 1001–2000 PLN; 2001–3000 PLN; more than 3000 PLN; refusal to answer), (9) existing comorbidities (coronary heart disease, diabetes mellitus, asthma, COPD, heart failure, kidney failure, and gastroesophageal reflux disease) (10) the number of medications taken (1 to 3; 4 to 6; 7 to 10; more than 10), (11) type of class of currently taken medicines (cardiac drugs, antihypertensive drugs, analgesics, digestive ailments drugs, anticoagulants, antidepressants, and nootropics), and (12) the type of medications and/or supplements bought without a prescription (analgesics, drugs for heartburn, herbal drugs, vitamins, others). Surveyed patients were also asked about vaccination against influenza (Table 1).


**Table 1.** General, clinical and psychological characteristics of the surveyed people.

**Table 1.** *Cont.*


**Table 1.** *Cont.*

