Prior to this, most blood donors were paid to give. The transfusion-transmissible infections that are most commonly tested for are hepatitis B virus (HBV), hepatitis C virus (HCV), human immunodeficiency virus (HIV), and syphilis. A study was conducted in China to determine the percentage of donors with a transfusion-transmissible infection and what classifications make a person more likely to get one of these infections. Some of the classifications relate to education, ethnicity, age and number of donations. Donors were tested for hepatitis B antigen using a screening test before donating blood, and if they tested for hepatitis B, they were excluded from the study . The results concluded that there is a higher rate of transfusion-transmissible infections among first-time donors, older donors, and donors other than Hans Chinese ethnicity. Donors with higher education were less likely to have a transfusion-transmissible infection (Zaller, Nelson, Ness, P., Wen, Kewir, Bai, & Shan,