Information was elicited on whether the participant had ever received hepatitis B vaccination and the number of doses received. Descriptive analysis was done using these data. Dichotomisation of data was also done for logistic regression analysis. As only those with ≥3 doses of hepatitis B vaccination uptake are considered fully protected,11 those with ≥3 doses were labelled ‘vaccinated’ and the rest ‘not vaccinated’. This was noted as the hepatitis B vaccination status of each participant. Here, PPIB is linked to hepatitis B virus infection.