**2.2 Study population**

Four hundred (400) students of both sexes with a mean age of 24.8 years who are studying at the institution were recruited to be part of this cross-sectional study between June through August 2019. After knowledgeable agreement was retrieved from each student who was between the ages of 16 and above and eligible for the study was identified during the study period and involved in the study. Data concerning the participants socio-demographic and risk factors were retrieved by a self-structured questionnaire.

### **2.3 Sample size determination**

Determination of sample size used for this study was done with the formula by Naing, [25] for calculation at 0.05 level of precision;

$$m = \frac{Z^2pq}{d^2}$$

Where:

**n** = required sample size.

**Z** = standard normal deviation at the necessary confidence interval (1.96) which agrees to 95% confidence interval.

**p** = prevalence of *H. pylori* from previous study (56.3%) (0.2) [26].

**q =** 1 – p = 0.9.

**d =** degree of precision expected (0.05)

$$n = \left(1.96\right)^2 \left(0.2\right) \left(0.9\right) / \left(0.05\right)^2 = 3.8416 \times 0.18 / 0.0025\tag{1}$$

$$3.8416 \times 0.18 / 0.0025 = 0.6915 / 0.0025 \tag{2}$$

$$0.6915/0.0025 = 276.6\tag{3}$$

$$n = 277 \tag{4}$$

To minimize error, this was however rounded up to 400 samples.

#### **2.4 Ethical approval and administration clearance**

Ethical clearance for this chapter was collected from the Health Research Ethics Committee (HREC) of the Federal Medical Centre, Keffi, Nigeria (FMC/KEF/ HREC/212/19). Official permission and administrative clearance was also received from the management of South Atlantic Petroleum Medical Center Keffi, Nasarawa State where specimens were obtained. In addition, each participant included in this study willingly completed and signed an informed consent form. Individual anonymity was treated with privacy and for the aim of the study.

#### **2.5 Blood sample collection**

Approximately 3 ml of blood specimen was drawn from each study participant by venipuncture into a plain tube and was labeled. Samples were left to clot at a minimal room atmosphere and spun at 3, 000 rpm for 5 minutes. The subsequent sera were collected into labeled cryovials and kept at -20 °C till set for analysis.
