Public health evaluation in the twenty-first century: time to see the wood as well as the trees.

This paper argues that concepts, methodologies and practices within public health need further development if they are to be sufficient to allow us to develop, undertake and evaluate interventions in the twenty-first century. The public health profession, and the disciplines that contribute to it, maintains the historical focus upon detailed micro analysis (individual and health sector) and not broader macro analysis (societal and system). This brief paper suggests why this is and outlines three challenges it poses: specifying and evaluating outcomes; specifying and understanding complex causal pathways in social interventions and the development of multisector evaluation, to meet information demands from multiple stakeholders. While there is general agreement that public health evaluation needs development, this paper argues that the focus needs to be more upon a broader evaluative space than is currently practiced. There is a need to move beyond primary and secondary health-related effects upon individuals, and focus more on evaluation of the wider range and distribution of direct and indirect effects upon individuals, communities and populations. That is, those involved in public health evaluation need to step back and first consider the wood before focusing in on specific trees

Adjuvanted H5N1 vaccine induces early CD4+ T cell response that predicts long-term persistence of protective antibody levels

Immune responses to vaccination are tested in clinical trials. This process usually requires years especially when immune memory and persistence are analyzed. Markers able to quickly predict the immune response would be very useful, particularly when dealing with emerging diseases that require a rapid response, such as avian influenza. To address this question we vaccinated healthy adults at days 1, 22, and 202 with plain or MF59-adjuvanted H5N1 subunit vaccines and tested both cell-mediated and antibody responses up to day 382. Only the MF59-H5N1 vaccine induced high titers of neutralizing antibodies, a large pool of memory H5N1-specific B lymphocytes, and H5-CD4+ T cells broadly reactive with drifted H5. The CD4+ response was dominated by IL-2+ IFN-γ− IL-13− T cells. Remarkably, a 3-fold increase in the frequency of virus-specific total CD4+ T cells, measurable after 1 dose, accurately predicted the rise of neutralizing antibodies after booster immunization and their maintenance 6 months later. We suggest that CD4+ T cell priming might be used as an early predictor of the immunogenicity of prepandemic vaccines

Changes in H5N1 influenza virus hemagglutinin receptor binding domain affect systemic spread

The HA of influenza virus is a receptor-binding and fusion protein that is required to initiate infection. The HA receptor-binding domain determines the species of sialyl receptors recognized by influenza viruses. Here, we demonstrate that changes in the HA receptor-binding domain alter the ability of the H5N1 virus to spread systemically in mice. The A/Vietnam/1203/04 (VN1203) and A/Hong Kong/213/03 (HK213) viruses are consistently lethal to domestic chickens but differ in their pathogenicity to mammals. Insertion of the VN1203 HA and neuraminidase (NA) genes into recombinant HK213 virus expanded its tissue tropism and increased its lethality in mice; conversely, insertion of HK213 HA and NA genes into recombinant VN1203 virus decreased its systemic spread and lethality. The VN1203 and HK213 HAs differ by 10 aa, and HK213 HA has shown greater binding affinity for synthetic α2,6-linked sialyl receptor. Introduction of an S227N change and removal of N-linked glycosylation at residue 158 increased the α2,6-binding affinity of VN1203 HA. Recombinant VN1203 virus carrying the S227N change alone or with the residue-158 glycosylation site removed showed reduced lethality and systemic spread in mice but not in domestic chickens. Wild-type VN1203 virus exhibited the greatest efficiency in systemic spread after intramuscular inoculation and in infection of mouse bone marrow-derived dendritic cells and conventional pulmonary dendritic cells. These results show that VN1203 HA glycoprotein confers pathogenicity by facilitating systemic spread in mice; they also suggest that a minor change in receptor binding domain may modulate the virulence of H5N1 viruses

Early and sustained innate immune response defines pathology and death in nonhuman primates infected by highly pathogenic influenza virus

The mechanisms responsible for the virulence of the highly pathogenic avian influenza (HPAI) and of the 1918 pandemic influenza virus in humans remain poorly understood. To identify crucial components of the early host response during these infections by using both conventional and functional genomics tools, we studied 34 cynomolgus macaques (Macaca fascicularis) to compare a 2004 human H5N1 Vietnam isolate with 2 reassortant viruses possessing the 1918 hemagglutinin (HA) and neuraminidase (NA) surface proteins, known conveyors of virulence. One of the reassortants also contained the 1918 nonstructural (NS1) protein, an inhibitor of the host interferon response. Among these viruses, HPAI H5N1 was the most virulent. Within 24 h, the H5N1 virus produced severe bronchiolar and alveolar lesions. Notably, the H5N1 virus targeted type II pneumocytes throughout the 7-day infection, and induced the most dramatic and sustained expression of type I interferons and inflammatory and innate immune genes, as measured by genomic and protein assays. The H5N1 infection also resulted in prolonged margination of circulating T lymphocytes and notable apoptosis of activated dendritic cells in the lungs and draining lymph nodes early during infection. While both 1918 reassortant viruses also were highly pathogenic, the H5N1 virus was exceptional for the extent of tissue damage, cytokinemia, and interference with immune regulatory mechanisms, which may help explain the extreme virulence of HPAI viruses in humans