目的 探讨百日咳疫苗接种对婴幼儿百日咳临床表现的影响。方法 回顾性分析不同百日咳疫苗接种状态的百日咳婴幼儿临床表现及外周血细胞水平的差异。结果 共入组1 083例<3岁百日咳患儿，其中未接种组551例，接种组532例；发病年龄<3月龄392例，含未接种372例，接种20例；≥3月龄691例，含未接种179例，接种512例。未接种组住院时间长于接种组（P < 0.05），呼吸衰竭的发生率高于接种组（P < 0.05）。≥3月龄未接种组重症肺炎的发生率高于接种组（P < 0.05）；重症肺炎的发生率在0剂次组最高（10.6%）， 4剂次组最低（1.2%）。在101例重症肺炎患儿中，未接种组占比79.2%（80例），仅21例（20.8%）发生在4个不同剂次接种组。≥3月龄患儿中，未接种组外周血白细胞计数、淋巴细胞绝对值及血小板计数均高于接种组（P < 0.05）。结论 百日咳疫苗接种可有效降低百日咳患儿重症肺炎、呼吸衰竭等并发症的发生率，减轻呼吸道并发症的严重程度。

Objective To study the effect of pertussis vaccination on the clinical manifestations of infants and young children with pertussis. Methods A retrospective analysis was performed to investigate the differences in clinical manifestations and peripheral blood cell levels between pertussis children with different pertussis vaccination status. Results A total of 1 083 children with pertussisat at age of <3 years were enrolled, with 551 children in the unvaccinated group and 532 in the vaccinated group. Of all the children, 392 had an age of onset of < 3 months (372 were unvaccinated and 20 were vaccinated) and 691 children had an age of onset of ≥ 3 months (179 were unvaccinated and 512 were vaccinated). Compared with the vaccinated group, the unvaccinated group had a longer length of hospital stay and a higher incidence rate of respiratory failure (P < 0.05). Among the children ≥ 3 months of age, the incidence of severe pneumonia in the unvaccinated group was higher than that in the vaccinated group (P < 0.05), and the incidence of severe pneumonia was the highest in the unvaccinated group (10.6%) and the lowest in the 4-dose vaccination group (1.2%). Among the 101 patients with severe pneumonia, 80 (79.2%) were observed in the unvaccinated group and only 21 (20.8%) in the four different doses vaccination groups. For the children with an age of onset of ≥ 3 months, the unvaccinated group had higher white blood cell count, absolute value of lymphocytes, and platelet count than the vaccinated group (P < 0.05). Conclusions Pertussis vaccination can reduce the incidence of severe pneumonia and respiratory failure and alleviate the severity of respiratory complications in infants and young children with pertussis.