Vaccine Preventable Disease Seroprevalence in a Nationwide Assessment of Timor-Leste (VASINA-TL): Study protocol for a population-representative cross-sectional serosurvey

Paul Arkell, Sarah L. Sheridan, Nelson Martins, Maria Y. Tanesi, Nelia Gomes, Salvador Amaral, Tessa Oakley, Vanessa Solano, Michael David, Anthony D.K. Draper, Nevio Sarmento, Endang da Silva, Lucsendar Alves, Carlito Freitas, Filipe de Neri Machado, Celia Gusmão, Ismael da Costa Barreto, Nicholas S.S. Fancourt, Kristine Macartney, Jennifer YanJoshua R. Francis

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INTRODUCTION: Historic disruption in health infrastructure combined with data from a recent vaccine coverage survey suggests there are likely significant immunity gaps to vaccine preventable diseases and high risk of outbreaks in Timor-Leste. Community-based serological surveillance is an important tool to augment understanding of population-level immunity achieved through vaccine coverage and/or derived from prior infection. METHODS AND ANALYSIS: This national population-representative serosurvey will take a three-stage cluster sample and aims to include 5600 individuals above 1 year of age. Serum samples will be collected by phlebotomy and analysed for measles IgG, rubella IgG, SARS-CoV-2 antispike protein IgG, hepatitis B surface antibody and hepatitis B core antigen using commercially available chemiluminescent immunoassays or ELISA. In addition to crude prevalence estimates and to account for differences in Timor-Leste's age structure, stratified age-standardised prevalence estimates will be calculated, using Asia in 2013 as the standard population. Additionally, this survey will derive a national asset of serum and dried blood spot samples which can be used for further investigation of infectious disease seroepidemiology and/or validation of existing and novel serological assays for infectious diseases. ETHICS AND DISSEMINATION: Ethical approval has been obtained from the Research Ethics and Technical Committee of the Instituto Nacional da Saúde, Timor-Leste and the Human Research Ethics Committee of the Northern Territory Department of Health and Menzies School of Health Research, Australia. Co-designing this study with Timor-Leste's Ministry-of-Health and other relevant partner organisations will allow immediate translation of findings into public health policy, which may include changes to routine immunisation service delivery and/or plans for supplementary immunisation activities.

Original languageEnglish
Article numbere071381
Pages (from-to)1-10
Number of pages10
JournalBMJ Open
Issue number5
Publication statusPublished - 18 May 2023


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