Hepatitis B vaccines

Biological challenges to effective vaccines in the developing world

The reason for holding a meeting to discuss biological challenges to vaccines is simple: not all vaccines work equally well in all settings. This special issue reviews the performance of vaccines in challenging environments, summarizes current thinking on the reasons why vaccines underperform and considers what approaches are necessary to understand the heterogeneity in responses and to improve vaccine immunogenicity and efficacy.

HPV vaccination's second act: promotion, competition, and compulsion

Developments regarding human papillomavirus (HPV) vaccines will transform HPV vaccination in the United States while simultaneously raising several new policy and ethical concerns. Policymakers, vaccine manufacturers, and the public health community must now respond to the presence of competing vaccines that are similar but distinct, particularly with respect to genital wart prevention and the benefits of vaccinating males. This work arises in the shadow of the contentious introduction of the HPV vaccine Gardasil (Merck & Co, Inc, Whitehouse Station, NJ) in 2006, particularly the opposition to efforts in many states to require the vaccine for school attendance. I review the current status of HPV vaccine policy in the United States and examine issues of public health ethics and policy central to ongoing and future HPV vaccination programs.

Long-term immunogenicity of preservative-free hepatitis B vaccine formulations in adults

Vaccination with recombinant hepatitis B vaccines is highly effective in preventing hepatitis B infection. Recently, a preservative-free (PF) formulation of hepatitis B vaccine [GlaxoSmithKline (GSK) Biologicals, Rixensart, Belgium] has been licensed. The immunogenicity of the PF hepatitis B vaccine and antibody persistence 6 years later was assessed in this study. This formulation was compared with the preservative- containing (PC) formulation of the vaccine and a low-preservative (LP) content formulation. Five hundred forty-one healthy adult subjects were evaluated in the primary study. Over 94% of the subjects in the three study groups had seroprotective anti-HBs antibody concentrations (>or=10 mIU/ml) 1 month after completing primary vaccination. Antibody measurements in 242 healthy adults who returned for the follow-up study and who had received primary vaccination 6 years earlier showed that over 81% of subjects in the three study groups still had anti-HBs antibody concentrations >or=10 mIU/ml. No apparent differences in antibody decline or distribution between the study groups were observed. These results indicate that the removal of preservatives from the hepatitis B vaccine does not affect adversely its immunogenicity both in the short and in the longer term.

Human papillomavirus infection and the primary and secondary prevention of cervical cancer

A wealth of evidence has led to the conclusion that virtually all cases of cervical cancer are attributable to persistent infection by a subset of human papillomavirus (HPV) types, especially HPV type 16 (HPV-16) and HPV-18. These HPV types also cause a proportion of other cancers, including vulvar, vaginal, anal, penile, and oropharyngeal cancers. Although cervical cancer screening, primarily with the Papanicolaou (Pap) smear, has reduced the incidence of this cancer in industrialized countries, cervical cancer remains the second most common cause of death from cancer in women worldwide, because the developing world has lacked the resources for widespread, high-quality screening. In addition to advances in Pap smear technology, the identification of HPV as the etiologic agent has produced 2 recent advances that may have a major impact on approaches to reduce the incidence of this disease. The first is the development of a preventive vaccine, the current versions of which appear to prevent close to 100% of persistent genital infection and disease caused by HPV-16 and HPV-18; future second-generation vaccines may be able to protect against oncogenic infections by a broader array of HPV types. The second is the incorporation of HPV testing into screening programs. In women aged >30 years, HPV testing can identify high-grade cervical intraepithelial neoplasia earlier than Pap smears with acceptable rates of specificity. These results, together with the high sensitivity of HPV testing, suggest that such testing could permit increased intervals for screening. An inexpensive HPV test in development, if successful, may be incorporated as part of an economically viable 'screen-and-treat' approach in the developing world. The manner in which vaccination and screening programs are integrated will need to be considered carefully so that they are efficient in reducing the overall incidence of cervical cancer.