OBJECTIVETo analyze the epidemiological characteristics and the bacterial pathogen composition of pneumonia among children under 5 years old in Ningbo.

METHODSIn 2013 February-April, we selected pediatric ward in three hospitals according to stratified cluster random sampling, and from which we collected all 57 556 hospitalized cases in January 2009-December 2012 period of children under 5 years old. A total of 16 740 medical records and bacterial spectrum records of pneumonia or bronchial pneumonia cases among children under 5 years old were described to calculate the proportions of children pneumonia or bronchial pneumonia hospitalized cases accounted for hospitalized children over the same period(referred to as proportions of pneumonia incidence), the detection rate of bacterial pathogens, proportions of bacterial spectrum, and to analyze the characteristics and bacterial pathogen composition of pneumonia among children under 5 years.

RESULTSThe proportions of children pneumonia in 2009-2012 were 26.16% (2 882/11 017), 31.23% (4 004/12 819), 29.35% (4 898/16 689) and 29.10% (4 956/17 031)(Z = 3.13, P < 0.01), and were in a downward trend by the increasing of age(Z = -113.74, P < 0.01). The proportions of children pneumonia of 0-5 age group were 50.71% (6 756/13 318), 26.60% (3 159/11 877), 24.17% (2 574 /10 648), 22.36% (2 509 /11 223) and 16.63% (1 745 /10 490). The proportions of children pneumonia with different season were 26.90% (3 725/13 850), 26.51% (3 788/14 287), 29.59% (4 442/15 011) and 33.21% (4 785 /14 408) (χ² = 198.77, P < 0.01). The proportions of severe children pneumonia of 0-5 age group were 1.10% (74/6 753), 0.47% (15/3 159), 0.19% (5 /2 574),0.08% (2 /2 509) and 0.06% (1 /1 745), with a downward trend by the age(F = 57.62, P < 0.01). The detection rate of Klebsiella pneumoniae, Haemophilus influenzae,Acinetobacter baumannii, Escherichia coli, Staphylococcus aureus, and Streptococcus pneumoniae was 19.3% (540/2 805), 16.4% (460/2 805), 13.6% (381/2 805), 11.9% (335/2 805), 11.5% (323/2 805) and 6.8% (192/2 805).

CONCLUSIONIn 2009-2012, the proportions of children pneumonia under 5 year old constituted a relatively high proportion in Ningbo city. Children under 1 year old were the major suffering group of pneumonia and severe pneumonia, which should be the key prevention group. The major bacterial pathogens of children's pneumonia in Ningbo are gram-negative bacteria.

Acinetobacter baumannii ; Child ; Epidemics ; Escherichia coli ; Gram-Negative Bacteria ; Haemophilus influenzae ; Humans ; Incidence ; Infant ; Klebsiella pneumoniae ; Pneumonia ; Staphylococcus aureus ; Streptococcus pneumoniae

OBJECTIVETo evaluate the breakthrough varicella infection rate and varicella vaccine effectiveness (VE) among children who received 1-dose varicella vaccine.

METHODSA total of 57 180 subjects for the consecutive 4-year birth cohorts were selected from the local children born between 2007 and 2010 in Yinzhou District, Ninghai County and Yuyao City. And they were followed up for varicella from 2008 to 2013. The recipients of the vaccinations were identified through Ningbo Immunization Information System and data on breakthrough infections among the recipients were collected by using China Information System for Disease Control and Prevention. The breakthrough varicella rate and the VE were calculated and the trends of them were described from 2008 to 2013 among 4-year birth cohorts. The cumulative incidence of varicella was compared between vaccinated and unvaccinated children among the consecutive 4-year birth cohorts.

RESULTSThe rate of varicella vaccine coverage, vaccine cumulative incidence among the cohorts was 96.74% (55 317/57 180) and 0.56% (321/57 180). The breakthrough varicella infection for 4-year birth cohorts was 0.44% (244/55 317), and for each birth cohort was 0.95% (142/14 928), 0.44% (61/13 855), 0.22% (29/13 433) and 0.09% (12/13 101), respectively. It was on the rise from 2008 to 2013 and the 2007 birth cohort of it increased fastest from 0.04% (6/14 928) in 2007 to 0.32% (48/14 834) in 2013. The vaccine cumulative incidence of these who vaccinated 1-dose varicella (the breakthrough varicella infection) was lower than these who were unvaccinated (the incidence: 6.25% (37/592), 3.52% (15/426), 3.69% (17/461) and 2.08% (8/384)) by each birth cohort (χ²= 130.27, P < 0.001 for 2007 birth cohort; χ²= 74.11, P < 0.001 for 2008 birth cohort; χ²= 162.80, P < 0.001 for 2009 birth cohort; χ²= 100.01, P < 0.001 for 2010 birth cohort). The vaccine effectiveness for 4-year birth cohorts was 89.33% (95% CI: 86.7%-92.1%) and for each birth corhort was 84.78% (95% CI: 77.94%-89.50%), 86.82% (95% CI: 77.82%-92.95%), 93.99% (95% CI: 89.27%-96.81%) and 95.60% (95% CI: 89.18%-98.21%), respectively. The effectiveness of each birth cohort declinedgradually from 2008 to 2013 and the 2009 birth cohort of it decreased fastest from 98.86% in 2010 to 66.83% in 2013.

CONCLUSIONSThe 1-dose varicella vaccine effectiveness was good, but breakthrough varicella infection rate was on the rise with time and the VE declined gradually from 2008 to 2013.

Chickenpox ; Chickenpox Vaccine ; Child ; China ; Humans ; Incidence ; Vaccination ; Vaccine Potency