Toh Zheng Quan, Tang Ke Xin, Vilivong Keoudomphone, Lai Jana, Bounkhoun Toukta, Chanthaluanglath Valin, Chanthongthip Anisone, Balloch Anne, Newton Paul N, Dubot-Pérès Audrey, Dance David A B, Licciardi Paul V, Russell Fiona M
Infection, Immunity and Global Health, Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, VIC 3052, Australia.
Department of Pediatrics, The University of Melbourne, Parkville, VIC 3052, Australia.
Vaccines (Basel). 2025 Aug 18;13(8):873. doi: 10.3390/vaccines13080873.
BACKGROUND/OBJECTIVES: Pneumococcal serotypes 1 and 5 are associated with invasive pneumococcal disease (IPD). However, data on the circulation of these serotypes in Asia following the introduction of the pneumococcal conjugate vaccine (PCV) is limited. The Lao People's Democratic Republic (Lao PDR) introduced PCV13 into its national immunisation programme in 2013. We undertook a serosurvey to assess the IgG responses to serotypes 1 and 5 from a convenience sample of children aged under 5 years in Vientiane, Lao PDR.
This cross-sectional analysis used a convenience sample of the close contacts of children under five years old who had been hospitalised with acute respiratory infections between 2013 and 2016 in Vientiane, Lao PDR. Serotype-specific IgG concentrations to serotypes 1 and 5 were measured using a modified WHO ELISA method.
A total of 214 participants were included, 130 of whom were unvaccinated and 84 were vaccinated with PCV13. Compared to unvaccinated participants, a higher number of PCV-vaccinated participants met the IgG threshold for IPD (≥0.35 μg/mL) [41.5% (54/130) vs. 71.4% (60/84)] for serotype 1. In contrast, for serotype 5, a similar number of participants in the PCV-vaccinated and unvaccinated group met the IgG threshold for IPD (85.7% (72/84) vs. 82.3% (107/130). Among unvaccinated children, serotype 1 IgG levels peaked at 12 and 23 months at 0.49 µg/mL (95% CIs: 0.25-0.96), while serotype 5 IgG levels were similar across age groups, ranging from 0.55 to 0.79 µg/mL.
Our findings indicate the considerable circulation of serotypes 1 and 5 within the community in Lao PDR. Ongoing surveillance is important for informing PCV vaccination strategies.
背景/目的：肺炎球菌1型和5型与侵袭性肺炎球菌疾病（IPD）相关。然而，在引入肺炎球菌结合疫苗（PCV）后，关于这些血清型在亚洲地区传播情况的数据有限。老挝人民民主共和国（老挝）于2013年将PCV13纳入其国家免疫规划。我们进行了一项血清学调查，以评估老挝万象5岁以下儿童便利样本中对1型和5型血清型的IgG反应。
这项横断面分析使用了2013年至2016年期间在老挝万象因急性呼吸道感染住院的5岁以下儿童密切接触者的便利样本。使用改良的世卫组织ELISA方法测量针对1型和5型血清型的血清型特异性IgG浓度。
共纳入214名参与者，其中130名未接种疫苗，84名接种了PCV13。与未接种疫苗的参与者相比，接种PCV疫苗的参与者中达到IPD的IgG阈值（≥0.35μg/mL）的人数更多，1型血清型为[41.5%（54/130）对71.4%（60/84）]。相比之下，对于5型血清型，接种PCV疫苗组和未接种疫苗组达到IPD的IgG阈值的参与者人数相似（85.7%（72/84）对82.3%（107/130））。在未接种疫苗的儿童中，1型血清型IgG水平在12个月和23个月时达到峰值，为0.49μg/mL（95%CI：0.25 - 0.96），而5型血清型IgG水平在各年龄组中相似，范围为0.55至0.79μg/mL。
我们的研究结果表明，1型和5型血清型在老挝社区内广泛传播。持续监测对于制定PCV疫苗接种策略很重要。
