TY - JOUR
T1 - A population-representative serosurvey estimating vaccine-induced immunity against measles, rubella, hepatitis B and severe acute respiratory syndrome coronavirus 2 in Timor-Leste
AU - Arkell, Paul
AU - Tanesi, Maria Y.
AU - Martins, Nelson
AU - Gomes, Nelia
AU - Oakley, Tessa
AU - Solano, Vanessa
AU - David, Michael
AU - Amaral, Salvador
AU - Sheridan, Sarah L.
AU - Yip, Teem Wing
AU - Draper, Anthony D.K.
AU - Sarmento, Nevio
AU - Soares da Silva, Endang
AU - Alves, Lucsendar
AU - Nicholson, Suellen
AU - Stambos, Vicki
AU - Pedrina, Kate
AU - Freitas, Carlito
AU - de Neri Machado, Filipe
AU - Gusmão, Celia A.
AU - da Costa Barreto, Ismael
AU - Fancourt, Nicholas S.S.
AU - Macartney, Kristine
AU - Yan, Jennifer
AU - Francis, Joshua R.
PY - 2025/3
Y1 - 2025/3
N2 - Background: Serosurveillance can be used to assess population immunity to vaccine-preventable diseases (VPDs). This study aimed to determine seroprevalence of four VPDs across Timor-Leste and identify immunity gaps. Methods: A population-representative three-stage cluster random sample of census-enumerated households were visited between October 2021 and February 2023. Occupants aged above one year were tested for measles immunoglobulin G (IgG), rubella IgG, hepatitis B surface antibody (HBsAb), hepatitis B core antibody (HBcAb) and severe acute respiratory syndrome 2 (SARS-CoV-2) IgG, using serological assays with a priori determined cut-offs. Sample- and response-weighted mixed effects logistic regression models were used to estimate seroprevalence in relevant age-strata. Findings: Of 2613 eligible households, 1908 (73.0%) participated. Of 8427 occupants, 4750 (56.4%) participated. Measles IgG seroprevalence was low among children, particularly those aged 10–14 (33.2%, 95% confidence interval (CI) 27.8–38.6%). Rubella IgG seroprevalence was high in all ages (93.2%, 95% CI 92.2–94.2%). SARS-CoV-2 IgG seroprevalence was high, including in young children not eligible for vaccination (74.0%, 95% CI 70.4–77.6%). HBsAb seroprevalence was lowest among adolescents aged 15–19 (12.1%, 95% CI 6.8–17.5%) but higher among younger children, who also had low HBcAb seroprevalence. Interpretation: The pattern of measles immunity is consistent with low virus transmission and suboptimal childhood vaccine uptake. These data have informed supplementary immunisation activities. High rubella IgG seroprevalence suggests recent or ongoing virus transmission and a need for congenital rubella syndrome surveillance. Hepatitis B data provide evidence of recent improvements in vaccine-induced immunity and protection. This study demonstrates how serosurveillance can directly influence national vaccine strategies. Funding: This study was funded by the Department for Foreign Affairs and Trade, Australian Government (Complex Grant Agreement Number 75889).
AB - Background: Serosurveillance can be used to assess population immunity to vaccine-preventable diseases (VPDs). This study aimed to determine seroprevalence of four VPDs across Timor-Leste and identify immunity gaps. Methods: A population-representative three-stage cluster random sample of census-enumerated households were visited between October 2021 and February 2023. Occupants aged above one year were tested for measles immunoglobulin G (IgG), rubella IgG, hepatitis B surface antibody (HBsAb), hepatitis B core antibody (HBcAb) and severe acute respiratory syndrome 2 (SARS-CoV-2) IgG, using serological assays with a priori determined cut-offs. Sample- and response-weighted mixed effects logistic regression models were used to estimate seroprevalence in relevant age-strata. Findings: Of 2613 eligible households, 1908 (73.0%) participated. Of 8427 occupants, 4750 (56.4%) participated. Measles IgG seroprevalence was low among children, particularly those aged 10–14 (33.2%, 95% confidence interval (CI) 27.8–38.6%). Rubella IgG seroprevalence was high in all ages (93.2%, 95% CI 92.2–94.2%). SARS-CoV-2 IgG seroprevalence was high, including in young children not eligible for vaccination (74.0%, 95% CI 70.4–77.6%). HBsAb seroprevalence was lowest among adolescents aged 15–19 (12.1%, 95% CI 6.8–17.5%) but higher among younger children, who also had low HBcAb seroprevalence. Interpretation: The pattern of measles immunity is consistent with low virus transmission and suboptimal childhood vaccine uptake. These data have informed supplementary immunisation activities. High rubella IgG seroprevalence suggests recent or ongoing virus transmission and a need for congenital rubella syndrome surveillance. Hepatitis B data provide evidence of recent improvements in vaccine-induced immunity and protection. This study demonstrates how serosurveillance can directly influence national vaccine strategies. Funding: This study was funded by the Department for Foreign Affairs and Trade, Australian Government (Complex Grant Agreement Number 75889).
KW - Global health
KW - Immunisation
KW - Serosurveillance
KW - Vaccine preventable diseases
UR - http://www.scopus.com/inward/record.url?scp=85218629512&partnerID=8YFLogxK
U2 - 10.1016/j.lansea.2024.100525
DO - 10.1016/j.lansea.2024.100525
M3 - Article
AN - SCOPUS:85218629512
SN - 2772-3682
VL - 34
SP - 1
EP - 19
JO - The Lancet Regional Health - Southeast Asia
JF - The Lancet Regional Health - Southeast Asia
M1 - 100525
ER -
