A Study On The Epidemic Of Pneumonia And The Effectiveness Of7-valent Pneumococcal Conjugate Vaccine Among Children Under5Years Old In Ningbo City

Purpose: To describe the epidemiological characteristics, the bacterial pathogen compositionand the tendency of pneumonia, and evaluate the effectiveness of7-valent pneumococcal conjugatevaccine(PCV7), among children under5years old in Ningbo, which will provide basic clues andorientations of children pneumonia prevention and may be useful to inform PCV7policy ofchildren.Methods: Stratified cluster random sampling was used to to select three hospitals. Themedical records from three hospitals between January1,2009and December31,2012werecollected, and the epidemiologic characteristics, bacterial spectrum and treatment cost of pneumonia(bronchial pneumonia) among children under5years old were described. The risk differencesbetween the PCV7-inoculated and non-inoculated subjects were compared, with prospective cohortstudy design, to evaluate the protective effect of PCV7. The database was built up by Epidata3.02,and statistical analyses were finished in PASW Statistics18.0.Results:1、16740eligible cases, accounting for29.08%of the total hospitalization patients, wereselected.2、As for the time distribution, the number of incident cases of pneumonia among childrenunder5years old reached the highest in December, and the second in March, while the lowest inJune.3、As for the age distribution, the children under1year old was the highest risk group(42.75%of all the and pneumonia (bronchial pneumonia) cases), with a downward trend by theage(F=136.48，P<0.0001). More importantly, this group were also the highest incident groupwith severe pneumonia (bronchial pneumonia)（F=47.053，P<0.001）.4、 The detection rate of bacterial pathogens was23.78%, and the Klebsiellapneumoniae(19.16%), Haemophilus influenzae(16.73%), Acinetobacter baumannii(13.65%),Escherichia coli(12.00%), Staphylococcus aureus(10.46%), and Streptococcus pneumoniae(7.05%)were the most common type. 5、The cost of children under1year old were significantly higher than others groups（P<0.000）.6、The prospective cohort study showed that the cumulative incidence rates of pneumoniaand bronchitis were2.08%、and4.58%in the PCV7-inoculated group, and3.33%and6.88%inthe non-inoculated group, prospective. The PCV-7vaccination was negatively associated withpneumonia (RR=0.443，95%CI：0.207～0.946) and bronchitis (RR=0.467，95%CI：0.254～0.861). The vaccine protective effect were54.59%（95%CI：5.40%～79.30%） and53.50%（95%CI：13.90%～74.60%）among infants under2years old, respectively.Conclusion: The pneumonia is one of the most common type diseases among children under5years old, which has become an important public health problem in Ningbo City. The incidenceof children’s pneumonia has obvious seasonality, which highly occurs in winter and spring.Children under1year old are the major suffering group of pneumonia and severe pneumonia,which should be the key prevention group. The major bacterial pathogens of children’s pneumoniain Ningbo are Klebsiella pneumoniae, Haemophilus influenzae, Acinetobacter baumannii,Escherichia coli, Staphylococcus aureu, and Streptococcus pneumoniae. The vaccination of PCV7among children under2years old can decrease the risk of the incidence of children’s pneumoniaand bronchitis.