American Journal of Law & Medicine

Overcoming barriers and ensuring access to HPV vaccines in low-income countries.(Symposium)

ABSTRACT

The inequitable burden of cervical cancer falls on women in poorer countries, due primarily to a disparity in access to screening services. To ensure that access to the new human papillomavirus ("HPV") vaccines is not similarly skewed toward higher-income populations, it is important to understand the appropriate priority group for receiving vaccines, the potential barriers to reaching that group, and the options for overcoming those barriers. Based on vaccine efficacy data, the likelihood of achieving high coverage with various groups, and the resultant cost-effectiveness ratios, it is widely agreed that young adolescent girls should be the primary recipients. Potential barriers include the fact that young adolescents are not currently reached by many health services; that there might be stigma attached to a vaccine for a sexually transmitted infection; that financing for the vaccine must be allocated; and that there is limited political commitment to women's health, to cancer prevention, or to this particular vaccine when so many other new vaccines are also becoming available. Despite these very real challenges, there is reason to be cautiously optimistic that those most in need of an HPV vaccine can receive it in programs that are affordable, effective, and acceptable to girls, their families, and their societies.

INTRODUCTION

Cervical cancer is a global problem that causes untold suffering and premature death, but its burden does not fall equally on women around the world. Of the nearly 500,000 new cases and about 274,000 deaths that occur each year, more than eighty percent occur in the developing world. (1) While relatively low incidence rates prevail in North America, Europe, and Japan (generally about 10 per 100,000 women), rates in sub-Saharan Africa are many times higher, as are those for poorer countries in Latin America and the Caribbean, Melanesia, South and Southeast Asia. In the Americas, Haiti has the highest estimated age-standardized rate per 100,000 women (87.3), while countries in East and Southern Africa also experience very high rates, such as Tanzania (68.6), Lesotho (61.6), Zambia (53.7) and Republic of Guinea (50.9). (2) This disparity in rates between North America and the rest of the Americas and Africa cannot be explained by simple geography. In fact, the United States and Europe both experienced much higher rates of cervical cancer well into the twentieth century, until screening and treatment programs were established by national health services. (3) In the United States, for example, rates have fallen by seventy-five percent or more since the 1960s, when screening was instituted. (4)

The differences in disease burden are due primarily to stark differences in both the availability and the utilization of screening and treatment services. While screening with cytology (the "Pap smear") has become a staple of women's health care in the developed world, very few women in the developing world have access to such screening. (5) This is due in large part to the difficulties governments face in establishing complex laboratory services that require coordinated, multi-visit screening and treatment services, and the inherent limitations in cytology as a screening tool. (6) In addition, cultural, social, and economic constraints keep women from taking advantage of these services when they are available. (7) These constraints include the social stigma associated with sexually transmitted infections (STIs) and with gynecological exams, the low status of women and their health needs in many societies, and the direct and indirect costs associated with clinic visits.

Human papillomavirus (HPV) vaccines represent a scientific breakthrough in their ability to prevent, with nearly 100 percent efficacy, persistent infection with the two HPV genotypes (known as types 16 and 18) that are the underlying cause of about seventy percent of cervical cancer cases. (8) Gardasil[R] (Merck, Whitehouse Station, New Jersey) is designed to prevent infection with types 16 and 18, as well as types 6 and 11 (which cause genital warts). (9) Gardasil[R] was licensed in the United States and Europe in 2006 and is now licensed in more than 100 countries. Cervarix[R] (GlaxoSmithKline, Rixensart, Belgium), designed to prevent types 16 and 18, was licensed in Australia and Europe in 2007 and is now licensed in more than seventy-five countries. (10) The high cost of these vaccines (about $100-150 per dose, with three doses needed) has led to heated debates about their use, in wealthy as well as poorer countries. (11) Questions remain, though, as to whether the vaccines can overcome the hurdles faced by screening programs in lower-income countries and finally deliver on the promise of cervical cancer prevention already enjoyed by women in the industrialized world. This paper elucidates the potential barriers that could prevent equitable access to the vaccines by those who need them most and describes strategies to address those barriers in low-income countries where the need is greatest.

I. IDENTIFYING THE PRIORITY GROUP FOR ACCESS

Before embarking on a discussion of access to HPV vaccines, it is essential that the priority group (those to whom vaccine should be directed first) is appropriately defined with a clear public health rationale. In the case of HPV vaccines, the priority group is determined by the efficacy of the vaccines, the likelihood of achieving high coverage, and the resultant cost-effectiveness ratio for various groups. With regard to efficacy, the clinical trials of the vaccines demonstrated that the vaccines are neither protective nor therapeutic for an HPV type with which a person has already been infected. (12) It would be extremely expensive and not very feasible to test girls or women for type-specific HPV history before vaccination. Since most girls and young women rapidly acquire HPV infection of at least one type within months or a few years of becoming sexually active, it is clear the vaccines will be most beneficial to girls who have not yet initiated sexual activity. (13) A study in England showed that even among young women with only one lifetime sexual partner, about half had acquired an HPV infection within four years of initiating sexual relations. (14) In the Phase 3 clinical studies of the quadrivalent vaccine, the protective efficacy of the vaccine against HPV types 16 and 18 was just forty-four percent (95 percent Confidence Interval [CI]: 31-55 percent) when all women 16 to 25 years old were included in the analysis regardless of their prior HPV-infection status). (15) While there are very few studies of sexual debut among young adolescents in developing countries, a study in four African countries found that among girls 12 to 14 years old, two to eight percent reported themselves as sexually experienced, while 11 to 42 percent reported a close friend as sexually experienced. …

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