Institut Pasteur, Center for Translational Research, Paris, France.
Department of Bacteriology, Pertussis Reference Laboratory, Pasteur Institute of Iran, Tehran, Iran.
PLoS One. 2020 Sep 1;15(9):e0238398. doi: 10.1371/journal.pone.0238398. eCollection 2020.
Pertussis remains endemic despite high vaccine coverage in infants and toddlers. Pertussis vaccines confer protection but immunity wanes overtime and boosters are needed in a lifetime. Iran, eligible for the Expanded Program on Immunization that includes the primary immunization, implemented two additional booster doses using a whole-cell vaccine (wPV) at 18 months-old and about 6 years-old. Duration of protection induced by the wPVs currently in use and their impact as pre-school booster are not well documented. This study aimed at assessing vaccination compliance and at estimating the duration of protection conferred by vaccination with wPV in children aged < 15 years in Tehran, Iran.
Detailed information on vaccination history and capillary blood samples were obtained from 1047 children aged 3-15 years who completed the 3 doses-primary pertussis immunization, in Tehran. Anti-pertussis toxin IgG levels were quantified by ELISA.
Compliance was very high with 93.3% of children who received the three primary and 1st booster doses in a timely manner. Timeliness of the 2nd booster was lower (63.3%). Rate of seropositive samples continuously and significantly increased from 1-2 to 5-6 years after 1st booster attaining 30.4% of children exhibiting serological sign of recent contact with B. pertussis. Second booster dating back 1 or 2 years was associated with high antibody titers, which significantly decreased within 3 years from injection. Among children who received 2nd booster injection more than 2 years before serum analysis, seroprevalence of pertussis infection was 8.4% and seropositivity rate was higher from the 10 years-old group.
Seropositivity in children aged 6-7 years with no 2nd booster supports the need for a vaccination at that age. Adolescent booster may also be considered.
尽管婴儿和幼儿的疫苗接种率很高，但百日咳仍然流行。百日咳疫苗可提供保护，但免疫力会随时间减弱，因此需要在一生中进行加强免疫。伊朗有资格实施扩大免疫规划，其中包括基础免疫，在 18 个月大和 6 岁左右使用全细胞疫苗（wPV）实施了两次额外的加强免疫。目前使用的 wPV 诱导的保护持续时间及其作为学前加强免疫的作用尚未得到充分记录。本研究旨在评估疫苗接种的依从性，并估计在伊朗德黑兰，wPV 接种对<15 岁儿童的保护持续时间。
从德黑兰 1047 名 3-15 岁完成 3 剂基础百日咳免疫的儿童中获取详细的疫苗接种史和毛细血管血样信息。采用 ELISA 法定量检测抗百日咳毒素 IgG 水平。
93.3%的儿童及时接种了 3 剂基础免疫和 1 剂加强免疫，接种依从性非常高。第 2 剂加强免疫的及时性较低（63.3%）。从第 1 剂加强免疫后 1-2 年到 5-6 年，血清阳性样本的比例持续且显著增加，达到 30.4%的儿童表现出近期接触 B. pertussis 的血清学迹象。第 2 剂加强免疫 1 或 2 年前接种的儿童，抗体滴度较高，接种后 3 年内显著下降。在进行血清分析前 2 年以上接受第 2 剂加强免疫的儿童中，8.4%的儿童感染百日咳，10 岁组的阳性率更高。
6-7 岁未接种第 2 剂加强免疫的儿童呈血清阳性，支持该年龄段需要接种疫苗。青少年加强免疫也可能需要考虑。
