Meeting Report: WHO consultation on considerations for regulatory expectations of Zika virus vaccines for use during an emergency.

On 1 February 2016, in the context of the ongoing Zika virus epidemic, the WHO declared that the recently reported clusters of microcephaly and other neurological disorders constituted a Public Health Emergency of International Concern (PHEIC). In response, WHO in collaboration with UNICEF and a working group of independent subject matter experts developed a Zika virus vaccine Target Product Profile (TPP) for use in an emergency, or in a future outbreak scenario. The drafting process of the Zika virus vaccine TPP included the opportunity for public comment, as well as consultation with epidemiologists, flavivirus vaccine subject matter experts, vaccine developers and global regulators to consider the regulatory expectations and potential emergency use pathways for a vaccine with the characteristics described in the TPP. This report summarizes an expert consultation held 6-7 June 2016 on the regulatory considerations for a Zika vaccine for emergency use.

Developing evidence-based immunization recommendations and GRADE.

The Strategic Group of Advisory Experts (SAGE) on immunization is an independent advisory committee with a mandate to advise the World Health Organization (WHO) on the development of vaccine and immunization related policies. SAGE working groups are established on a time-limited basis to review and provide evidence-based recommendations, together with their implications, for open deliberation and decision-making by SAGE. In making its recommendations, SAGE takes into consideration: the epidemiologic and clinical characteristics of the disease; vaccine and immunization characteristics; economic analysis; health system considerations; the existence of and interaction with other intervention and control strategies; costing and social impacts; and legal and ethical concerns. Since 1998, WHO has produced evidence-based vaccine position papers for use primarily by national public health officials and immunization programme managers. Since April 2006 all new or updated position papers have been based on SAGE recommendations. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach has been adopted by WHO and, since 2008, GRADE tables that rate the quality of evidence have been produced in support of key recommendations. SAGE previously expressed concern that GRADE was not ideally suited to many immunization-specific issues such as the vaccine population level effect and the inclusion of surveillance system data, particularly for vaccine safety. Extensive productive interactions with various advisory groups including the US Advisory Committee on Immunization Practices, the European Centres for Disease Control, the German Standing Committee on Vaccination (STIKO), WHO's Global Advisory Committee on Vaccine Safety and the GRADE working group resulted in key enhancements to accommodate vaccine-relevant evidence. This facilitated integration and acceptability of the GRADE approach in the development of immunization related SAGE and WHO recommendations. Ongoing utilisation should result in further fine-tuning of the approach to ensure that recommendations are based on the full range of appropriate evidence.