Low- and Moderate-risk Cohort:

Inclusion Criteria:

1. Signed informed consent form (ICF) of the study.
2. Age > 40 years.
3. Willingness to fill in the study questionnaire.
4. No clinically relevant symptoms as assessed by the investigator, subjects with existing medical conditions may be eligible given that they are symptom free and that full treatment of the condition is medically confirmed.
5. Willingness to participate in future visits.

Exclusion Criteria:

1. Self-reported pregnancy (no test).
2. Indications of clinically relevant medical conditions in self-reported healthy subjects.
3. Self-reported symptom-free HIV, HCV and HBV infections. If HIV, HBV or HCV serology test is done and any of them are positive, the subject will be considered a screen failure.
4. Any conditions preventing blood-draw.
5. Vulnerable subjects.
6. Foreseeable lack of compliance.
7. Participation in another sample collection project of the same sponsor, in order to avoid double evaluation of the same subject.
8. Participation (currently or in the past month) in an early phase clinical trial (phases I and II) involving testing of pharmaceutical products, if the last dose of pharmaceutical product administration was within 30 days of the first sample collection, and / or further pharmaceutical product administration is planned.
9. Vaccination within the last 14 days.

High-risk Cohort:

Inclusion Criteria:

1. Signed informed consent form (ICF) of the study.
2. Age > 50 years.
3. Willingness to fill in the study questionnaire.
4. Willingness to participate in future visits and medical investigations, the presence of at least 2 of the following 3 risk factors (inclusion criteria #5-7):
5. Hypertension, receiving antihypertensive treatment.
6. Dyslipidemia/ Hypercholesterolemia (>5.2mmol/L total cholesterol level), on or not on statin-treatment.
7. Active or former smoker, with smoking history of at least 20 pack-years, and/or the presence of intermediate lung nodule on prior LDCT testing.
8. No clinically relevant symptoms as assessed by the investigator; subjects with existing medical conditions may be eligible given that they are symptom free and that treatment of the condition is well documented.

Exclusion Criteria:

1. Self-reported pregnancy (no test).
2. Cardiovascular disease (including obstructive coronary artery disease, peripheral artery disease, aortic aneurysm) or other clinically significant heart disease (congenital, valvular heart disease, cardiomyopathy, heart failure and heart disease requiring ICD [implantable cardioverter defibrillator] or pacemaker therapy).
3. Interstitial lung disease or severe COPD (chronic obstructive pulmonary disease) in GOLD stages 3 or 4.
4. Active cancer or malignant disease with less than 5 years history of remission.
5. Indications of clinically relevant medical conditions in self-reported healthy subjects, especially if (a) the condition requires regular or constant specialist checkups, or (b) pharmacological therapy indicates the presence of significant NCDs or multimorbidity, i.e., chronic polypharmacy (use of 5 or more medications at enrollment or over the last 6 months), or drug therapy necessitating a specialist input for initiation or management (e.g., combined anti-diabetic treatment with two or more medications).
6. Self-reported symptom-free HIV, HCV and HBV infections. If HIV, HBV or HCV serology test is done and any of them are positive, the subject will be considered a screen failure.
7. Any conditions preventing blood-draw or CT scans.
8. Vulnerable subjects.
9. Foreseeable lack of compliance.
10. Participation in another sample collection project of the same sponsor, in order to avoid double evaluation of the same subject. 'High-risk' subjects enrolled in the low- and moderate-risk arm of the H4H study might be reallocated to the high-risk study arm after the first 4-5 visits.
11. Participation (currently or in the past month) in an early phase clinical trial (phases I and II) involving testing of pharmaceutical products, if the last dose of pharmaceutical product administration was within 30 days of the first sample collection, and/or further pharmaceutical product administration is planned.
12. Vaccination within the last 14 days of sample collection.