A case study of an influenza vaccination program for health care workers in Vietnam.

BACKGROUND: In 2017, the Vietnam Ministry of Health conducted a demonstration project to introduce seasonal influenza vaccination to health care workers. A total of 11,000 doses of influenza vaccine, single-dose prefilled syringes, were provided free to HCWs at 29 selected hospitals, clinics, and research institutes in four provinces: Hanoi, Khanh Hoa, Dak Lak and Ho Chi Minh City. METHODS: Before the campaign, a workshop was organized to discuss an implementation plan including technical requirements, cold chain, uptake reporting, and surveillance for adverse events following immunization. All sites distributed communication materials and encouraged their staff to register for vaccination. Following immunization sessions, sites sent reports on uptake and adverse events following immunization. Left-over vaccine was transferred to other sites to maximize vaccine use. RESULTS: The average uptake was 57% for all health care workers, with 11 sites achieving 90% and above. These 11 sites were small with less than 500 staff, including 5 primary hospitals, 3 preventive medicine units, and 2 referral hospitals. Among the six biggest sites with over 1000 staff, four sites had the lowest uptake (14-47%). Most of the high-uptake sites were from the central to the south; only one site, a referral hospital, was from the north. After redistribution of left-over vaccine, only 130 vaccine doses (1.2%) were not used and destroyed. Based on factors that affected uptake, including registration levels, differing communication strategies, availability of vaccination, and commitment by health facility leaders, we recommended ways to increase health care worker coverage; recommendations to improve reporting adverse events following immunization were also made. CONCLUSIONS: The project demonstrated that it was feasible to conduct influenza vaccination campaigns among health care workers in Vietnam. Improvements in promotion of registration, more intense pre-planning, especially at larger facilities, and wider, more consistent availability of communication materials will result in increased efficiency and coverage in this program's future expansion.

Development of a highly sensitive magneto-enzyme lateral flow immunoassay for dengue NS1 detection.

BACKGROUND: Dengue infection represents a global health issue of growing importance. Dengue non-structural protein 1 (NS1) plays a central role in the early detection of the disease. The most common method for NS1 detection is testing by lateral flow immunoassays (LFIAs) with varying sensitivity. In this study, we present a highly sensitive magneto-enzyme LFIA for prompt diagnosis of dengue. METHODS: We have demonstrated the development of a magneto-enzyme LFIA combining super-paramagnetic nanoparticles as labels and Biotin-Streptavidin signal amplification strategy to detect dengue NS1. Factors affecting the test performance including antibody pair, super-paramagnetic nanoparticle size, nitrocellulose membrane type, amounts of detection and capture antibodies, and amounts of Streptavidin-polyHRP were optimized. Analytical sensitivity and cross-reactivity were determined. Clinical performance of the novel assay was evaluated using a panel of 120 clinical sera. RESULTS: This newly developed assay could detect NS1 of all four serotypes of dengue virus (DENV). The limit of detection (LOD) was found to be as low as 0.25 ng ml-1 for DENV-1 and DENV-3, 0.1 ng ml-1 for DENV-2, and 1.0 ng ml-1 for DENV-4. The LOD for DENV-2 was a 50-fold improvement over the best values previously reported. There was an absence of cross-reactivity with Zika NS1, Hepatitis B virus, Hepatitis C virus, and Japanese encephalitis virus. The sensitivity and specificity of the novel assay were 100% when tested on clinical samples. CONCLUSIONS: We have successfully developed a magneto-enzyme LFIA, allowing rapid and highly sensitive detection of dengue NS1, which is essential for proper management of patients infected with DENV.