Vaccines have prevented countless infections but poor vaccine responses remain a major challenge in many scenarios. Hepatitis B vaccine nonresponses are common but immunologically not well-understood. This study aims to study the immunology of hepatitis B vaccine responses by comparing traditional HBV vaccine, which is associated with nonresponses in some patients, to CpG-adjuvanted HBV vaccine, which is associated with far fewer rates of nonresponses. This research will build upon prior studies of the human immune response to infection to gain a deeper understanding of the complexity of these responses. This information will be broadly useful as many vaccine candidates fail due to lack of immunogenicity, potentially enabling improved vaccine design and better protection.