(Un)contested Evidence: Scientific Literature, Systematic Reviews and the Politics of Evidence in the Introduction of HPV Vaccines in Colombia

"...how to provide reliable, trustworthy but simple information to policymakers about scientific evidence?"

In Colombia, the introduction of human papillomavirus (HPV) vaccines imposed on public health authorities the need to justify the choice of the right vaccine for the national immunisation programme by testing the tools of evidence-based medicine (EBM), one of which is systematic reviews. Systematic reviews are designed to help people navigate the complexities of scientific literature through a clear and simple account of the knowledge on a particular issue. However, as Oscar Javier Maldonado Castañeda explains in this article, systematic reviews are shaped according to the interest of the local groups that produce them. By exploring the formatting, making, and managing of systematic reviews of evidence relating to HPV vaccines in Colombia, he shows the ways in which systematic reviews mediate between the requirement of presenting the evidence that emerges from the international literature and the necessity of having data locally relevant.

Noting that the use of systematic reviews to inform public decision-making is relatively rare in the global south, Castañeda reports that 2 institutions were involved in the making of systematic reviews for the introduction of HPV vaccines in Colombia: Universidad Nacional (UNAL 2009, 2011) and Colombian National Cancer Institute (INC 2011). Drawing on document analysis and 20 interviews with members of the National Committee of Immunisations Practice (NCIP), the article describes the role of systematic reviews in the controversy around the choice between Gardasil (quadrivalent HPV vaccine) and Cervarix (bivalent vaccine). The main function of the NCIP is to manage evidence and to give advice to the Ministry of Health based on that.

Castañeda analyses each of the reviews and questions what kind of "evidence" was included. For example, in the case of the INC systematic review, what is discussed is not the performance of HPV vaccines in relation to different epidemiological profiles of HPV infection but, rather, the "trust" that regulatory authorities and healthcare institutions have in the safety and the efficacy of these vaccines. He argues that the systematic review, in this case, is "a device to introduce local (Colombian) policymaking into an extended network of institutions and policies. This international support provides legitimacy to the national introduction of the vaccine."

As Castañeda observes, both systematic reviews were focused on cervical cancer and pre-cancerous lesions and HPV vaccines but neither addressed the issue of genital warts and other cancers linked to HPV infection. He argues that the burden of genital warts is a key factor in the choice of Gardasil as against Cervarix as the vaccine for public vaccination programmes in Colombia. Most of the time, the relation between other cancers related to HPV infection, such as throat and anal cancer, and vaccines is kept invisible because of its relation with non-hetero-normative sexualities like anal and oral sex.

Table 1 presents the most contested aspects of the debate between Gardasil and Cervarix as the right vaccine for the immunisation programme. None of these elements is presented in the systematic reviews made by INC or UNAL. The key elements that shape the debate cannot be addressed by the technology of systematic reading and organising of the scientific literature about the subject, according to Castañeda.

"Some members of the committee perceived that the systematic review and the models produced by UNAL was extremely partial, and maximised explicitly the burden of genital warts and minimised the problem of cross-protective efficacy." Furthermore, as Castañeda shows, there is a gap between the consensus enacted in the minutes and the controversy that can be reconstructed through interviews with committee members.

In conclusion: "A view of systematic reviews in practice shows how local and practical concerns shape the design of the review and thus interfere in the enactment of evidence. At least two alternatives of calculation were formulated in order to present the evidence gathered as legitimate. One strategy relies on locating the local case in an international network of texts and institutions part of the EBM movement. Another strategy was gathering data from local studies made by local communities. The legitimacy of evidence depends on emphasising its local nature."