Risk factors for pertussis among children hospitalized for pertussis during 2016-2017, in Guizhou Province of China: a case-control study

Aim:Pertussis is a respiratory tract infection,the vaccine for which was introduced in the Expanded Programme on Immunization(EPI)in Guizhou Province of China(hereafter referred as Guizhou)in the 1980s.This vaccine rapidly decreased incidence rates of pertussis in the province,however,despite the wide high coverage of the diphtheria,tetanus and acellular pertussis(DTaP)combined vaccine,there has been a resurgence of pertussis since 2014.Even with this recent increase in disease transmission,risk factors for pertussis infection have not been evaluated in Guizhou.We aimed to provide information on pertussis risk factors and insight on designing targeted pertussis control policies and measures through this study.Methods:A 1:2 matched retrospective case-control study was conducted between 2016 and 2017,involving infants and children younger than 6 years old and parents of the participants.The enrolled cases included clinical and laboratory confirmed pertussis cases according to the WHO-recommended pertussis definition.Controls were selected from children in the same neighborhood who were not diagnosed with pertussis prior to our investigation and did not exhibit any clinical manifestations of pertussis.Results:The household size[Matched odds ratio(OR_(m)=1.4,95%confidence interval(Cl):1.1-1.7]and household members with antecedent cough(OR_(m)=3.6,95%CI:1.8-7.2)were significantly associated with their child’s pertussis onset.The parents’occupations were significantly associated with their child’s pertussis onset(ORm=9.4,95%CI:1.6-54.8,for mother side;ORm=4.5,95%CI:1.2-16.5,for father side),when they worked in the business and/or service industry.Having family members with a history of cough was an independent risk factor for pertussis[Adjusted odds ratio(AOR)=43.6,95%CI:2.7-694.0].Besides,the parents’demographic characteristics and DTaP doses were not found to be independent factors.Conclusion:Household exposure is an important risk factor for pertussis infection in infants and young children and should therefore be considered as a major factor during formulation of pertussis control policies and measures.

Prevalence and factors associated with pentavalent vaccination:a cross-sectional study in Southern China

Background Immunization is one of the most far-reaching and cost-effective strategies for promoting good health and saving lives.A complex immunization schedule,however,may be burdensome to parents and lead to reduced vaccine compliance and completion.Thus,it is critical to develop combination vaccines to reduce the number of injections and simplify the immunization schedule.This study aimed to investigate the current status of the pentavalent diphtheria-tetanus-acellular pertussis inactivated poliomyelitis andHaemophilus influenzae type B conjugate(DTaP-IPV/Hib)vaccination in Southern China as well as explore the factors in the general population associated with uptake and the differences between urban and rural populations.Methods A cross-sectional study was conducted with recently enrolled kindergarten students in Hainan Province between December 2022 and January 2023.The study employed a stratified multistage cluster random sampling method.Information regarding the demographic characteristics and factors that influence decisions were collected from the caregivers of children via an online questionnaire.Multivariate logistic regression was used to determine the factors associated with the status of DTap-IPV/Hib vaccinations.Results Of the 4818 valid responses,95.3%of children were aged 3-4 years,and 2856(59.3%)held ruralhukou.Coverage rates of the DTaP-IPV/Hib vaccine,from 1 to 4 doses,were 24.4%,20.7%,18.5%,and 16.0%,respectively.Caregivers who are concerned about vaccine efficacy[adjusted odds ratio(aOR)=1.53,95%confidence interval(CI):1.30-1.79],the manufacturer(aOR=2.05,95%CI:1.69-2.49),and a simple immunization schedule(aOR=1.26,95%CI:1.04-1.54)are factors associated with a higher likelihood of vaccinating children against DTaP-IPV/Hib.In addition,caregivers in urban areas showed more concern about the vaccine price(P=0.010)and immunization schedule(P=0.022)in regard to vaccinating children.Conclusions The DTaP-IPV/Hib vaccine coverage rate in Hainan Province remains low.Factors such as lower socioeconomic status,cultural beliefs,concerns about vaccine safety,and cost may hinder caregivers from vaccinating their children.Further measures,such as health education campaigns to raise knowledge and awareness,and encouragement of domestic vaccine innovation,which would reduce out-of-pocket costs,could be implemented to improve the coverage of DTap-IPV/Hib vaccination.