目的 探讨影响百日咳患儿血清百日咳毒素抗体（PT-IgG）水平的相关因素。方法 回顾性分析2018年4月1日至2019年7月31日住院治疗的百日咳患儿的临床资料。分析不同病程、百日咳疫苗接种剂次、发病年龄、疾病严重程度对于百日咳患儿PT-IgG水平的影响。结果 共纳入638例患儿,其中未接种组313例,男177例、女136例,中位年龄78.0（52.0~125.0）天;接种组325例,男163例、女162例,中位年龄232.0（144.0~483.0）天。未接种组患儿不同采样时病程（≤14d、15~21d、>21d）组间不同PT-IgG水平分布差异有统计学意义（P<0.01）;病程>21d组PT-IgG≥80 IU/mL的比例较高。接种组患儿不同采样时病程组间不同PT-IgG水平分布差异有统计学意义（P<0.01）;病程15~21d组和>21d组PT-IgG≥80 IU/mL的比例较高。不同疫苗接种剂次组之间PT-IgG水平的差异有统计学意义（P<0.01）;随着疫苗接种剂次增加,PT-IgG水平逐渐增高。未接种组中,无论重症组还是普通组,不同采样时病程之间PT-IgG水平的差异均有统计学意义（P<0.05）。接种组中,普通组不同采样时病程之间PT-IgG水平的差异有统计学意义（P<0.05）。结论 我国百日咳鲍特菌急性感染期患儿PT-IgG不高,59.9%低于20IU/mL;PT-IgG水平受到疫苗接种剂次及采样时病程的影响。

Objective To investigate the relative factors of serum pertussis toxin antibodies (PT-IgG) in children with pertussis.Methods Clinical data of children hospitalized with pertussis from April 1, 2018 to July 31, 2019 were retrospectively analyzed. To analyze the influence of different course of disease, pertussis vaccine dose, onset age and disease severity on PT-IgG level in children with pertussis. Result A total of 638 children were included. In the unvaccinated group, 313 patients (177 boys and 136 girls) had a median age of 78.0 (52.0-125.0) days. In the vaccination group, there were 325 patients (163 boys and 162 girls) with a median age of 232.0 (144.0-483.0) days. There were statistically significant differences in the distribution of PT-IgG levels among different disease course groups at sampling (≤14d, 15-21d, >21d) in the unvaccinated group (P<0.01). The proportion of PT-IgG≥80 IU/mL was higher in patients with disease course >21 days. There was significant difference in PT IgG level between different vaccine groups (P<0.01). The proportion of PT-IgG≥80 IU/mL was higher in patients with disease course of 15~21 days and >21 days. There were statistically significant differences in PT-IgG levels between groups receiving different doses of vaccine (P<0.01). The levels of PT-IgG gradually increased with the increase of vaccine doses. In the unvaccinated group, no matter in the severe group or the normal group, the difference of PT-IgG level among different disease course groups at sampling was statistically significant (P<0.05). In the inoculation group, the difference of PT-IgG levels among different disease course groups at sampling in the normal group was statistically significant (P<0.05).Conclusions The level of PT-IgG in children with acute infection of Bordetella pertussis in China was not high, and 59.9% of them had a PT-IgG level lower than 20IU/mL. PT-IgG levels were affected by the dose of vaccine and the course of disease at the time of sampling.