Objective To better understand and measure the effect from 10-year immunization activities,we conducted seroepidemiological study using the remaining blood samples of the nationwide survey of Nutrition and Health in Chinese residents in 2002.Methods HBsAg,anti-HBs and anti-HBc in blood samples were tested using ELISA reagents and revised by SPRIA and Abbott ELISA reagents.Results Among the children aged(3-12) yearold,the prevalence rate of HBsAg is 5.03%,the rate of HBV infection is 29.10%. For the vaccinated children,the rates are 3.63% and 26.88% respectively.For the unvaccinated children,the rates are 11.19% and 47.03% respectively.Among the children,the rate of HBsAg is 2.07% in urban areas and 8.17% in rural areas.For the vaccinated children,the rate of HBsAg is 1.96% in urban areas and 6.65% in rural areas. For the unvaccinated children,the rate of HBsAg is 2.39% in urban areas and 10.84% in rural areas.Conclusion The prevalence rates of HBsAg and HBV infection have obviously declined in the children aged 3-12 year-old.And the effect from 10-years immunization activities has achieved great success.

Objective To know the status of Hepatitis B of the Eastern,Middle,and Western areas in China.Methods We analyzed the data of the seroepidemiological study using the remaining blood samples of the nationwide survey of Nutrition and Health in Chinese residents,which was done in 2002.Results (1)Among population in the Eastern areas,the adjusted prevalence rate of HBsAg is 9.20%,the rate of HBsAg is 4.29% in the urban areas and 11.79% in the rural areas.For15-years-old children,the rate is 6.46% in the whole children,2.29% in the urban areas and 12.39% in the rural areas respectively.(2)Among population in the Middle areas,the adjusted prevalence rate of HBsAg is 7.24%,the rate of HBsAg is 4.41% in the urban areas and 7.84% in the rural areas.For15-years-old children,the rate is 4.47% in the whole children,1.61% in the urban areas and 6.82% in the rural areas respectively.(3)Among the whole population in the Western areas,the adjusted prevalence rate of HBsAg is 8.24%,the rate of HBsAg is 4.53% in the urban areas and 9.05% in the rural areas.For15-years-old children,the rate is 5.48% in the whole children,2.57% in the urban areas and 7.35% in the rural areas respectively.Conclusions The results show that the prevalence rate of the HBsAg of the Eastern,Middle,and Western areas in China has obviously been descending in different levels,especially to the children less than 15 years old,and suggest that the impacts of(Hepatitis B) are prominent in these areas since the Hepatitis B vaccine has been introduced into expanded program on immunization(EPI) since 1992.

Objective To observe the positive rate and distribution characteristic of the serum IgG antibody to severe acute respiratory syndrome(SARS)coronavirus among different populations,especially the healthy children aged≤14 years old. Methods This study has confirmed and analyzed the reliability and consistence of 2 enzyme-linked immunosorbent assay(ELISA), and evaluated the practical value of specific IgG testing on SARS diagnosis,by 2 ELISA,utilizing the antigens of resolved fluid of the whole virus (CoV) and the purified N protein respectively test the specific antibody of 70 SARS cases,55 healthy infants aged 3-6ms,297 healthy children aged ≤14 ys and 156 healthy adults aged ≥15 ys.The sensitivity,specificity,positive predictive value (PPV),negative predictive value (NPV) and veracity of the 2 ELISA tests were used to evaluate the utility value on laboratory diagnosis of SARS.Kappa and χ 2 were used to evaluate the consistence and difference between the testing results. Results The results showed that the positive rates tested by ELISA using the whole virus as antigen were 75.71% in SARS cases,36.36% in healthy infants,23.91% in healthy children and 1.92% in healthy adults.The positive rates were 51.16% in 0 age group,41.89% in 1 year old group,30.95% in 2 years old group,18.60% in 3 years old group,16.67% in 4 years old,group 2.38% ( in 5-9 years) old group and 4.76% in 10-14 years old group,respectively.With the increase of age the antibody positive rate showed downtrend.The antibody positive rate tested by ELISA using N protein was 80% in SARS cases and negative in healthy population including all age groups.For people ≥15 years old,the consistence of the results by 2 ELISA methods in measurements of SARS antibodies was very high.The kappa value was 0.881,and there was no significant difference(χ 2=0.10,P0.05). For children ≤14 years old,there was significant difference(χ 2=89.0,P0.005).The sensitivity,specificity,PPV,NPV and veracity of 2 ELISA methods on the diagnosis of SARS were 75.71%,81.50%,36.05%,96.06%,80.80% and 80.00%,100.0%,100.0%,97.32%,97.58%,respectively.There were significant differences on specificity,PPV and veracity. Conclusion The whole virus ELISA test could be used to diagnose the adult SARS whose disease course was above 10 days,but the N protein ELISA test was more specific and more verified which was helpful to diagnose the SARS cases of different age groups,especially the children SARS which is difficulf in identification.This method was widely used to confirm the clinical diagnosis and the serum epidemiological investigation and had important reference value.

OBJECTIVETo better understand and measure the impact from immunization activities over the last 10-years, we conducted a sero-epidemiological study using the remaining blood samples of a nationwide survey on Nutrition and Health in Chinese residents, in 2002.METHODSHBsAg, anti-HBs and anti-HBc in blood samples were tested using enzyme-linked immunosorbent assay(ELISA) reagents and revised by solid phase radioimmunoassay and Abbott ELISA reagents.RESULTSAmong population older than 3 years, the prevalence rates of HBsAg, anti-HBs and hepatitis B virus(HBV) infection were 9.09%, 37.48% and 50.04% but for children between 3 and 12 year olds, they were 5.03%, 45.33% and 29.10% respectively. Among population older than 3 years, the rates of HBsAg and HBV infection in urban area were 4.61% and 43.51%, but the rates in rural area were 9.41% and 56.77% respectively while for children from 3-years to 12-years old, they rates were 2.10%, 20.45% in urban area and 8.25%, 39.22% in rural areas, respectively.CONCLUSIONResults revealed that since the hepatitis B vaccine was introduced into the expanded program on immunization(EPI) from 1992, the prevalence rates of HBsAg and HBV infection, especially in the children from 3 to 12 years of age, had obviously declined, suggesting that some changes had happened in the epidemic characters of hepatitis B in China.

Objective To understand and measure the effect of 10-years immunization activities,we decided to conduct seroepidemiological study using the remaining blood sampling of Nationwide Survey of Nutrition and Health in Chinese residents,which was conducted in 2002.Methods HBsAg,anti-HBs,and anti-HBc in blood samples were detected using ELISA reagents and revised by SPRIA and Abbott ELISA reagents.Results(1)Among the vaccinated population,the adjusted prevalence rate of HBsAg is 5.28%,and the rate of HBV infection is 54.44%.For the vaccinated children from 3-12 years old,the rate is 3.63% and 26.88%,respectively.(2)Among the unvaccinatted population,the rate of HBsAg is 9.51% and the rate of HBV infection is 64.63%.For the children of 3-12 years old,the rate is 11.19% and 47.03% respectively.(3)Among the vaccinatted population,the rate of HBsAg is 2.55% in urban area and 7.10% in rural area.For the unvaccinatted population,the rate is 7.24% and 10.12%,respectively.Among the vaccinatted children from 3-12 years old,the rate of HBsAg is 1.96% in urban area and 6.65% in rural area.For the unvaccinated children,the rate is 2.39% and 10.84%,respectively.Conclusion The results showed that the effect of 10years immunization activities is prominent and suggested that it was the most important to improve the coverage of hepatitis B vaccine in the rural children for prevention and control campaign of hepatitis B.

Most cases of severe acute respiratory syndrome (SARS) have occurred in close contacts of SARS patients. However, in Beijing, a large proportion of SARS cases occurred in persons without such contact. We conducted a case-control study in Beijing that compared exposures of 94 unlinked, probable SARS patients with those of 281 community-based controls matched for age group and sex. Case-patients were more likely than controls to have chronic medical conditions or to have visited fever clinics (clinics at which possible SARS patients were separated from other patients), eaten outside the home, or taken taxis frequently. The use of masks was strongly protective. Among 31 case-patients for whom convalescent-phase (>21 days) sera were available, 26% had immunoglobulin G to SARS-associated coronavirus. Our finding that clinical SARS was associated with visits to fever clinics supports Beijing’s strategy of closing clinics with poor infection-control measures. Our finding that mask use lowered the risk for disease supports the community’s use of this strategy.

Superspreading events were pivotal in the global spread of severe acute respiratory syndrome (SARS). We investigated superspreading in one transmission chain early in Beijing's epidemic. Superspreading was defined as transmission of SARS to at least eight contacts. An index patient with onset of SARS 2,months after hospital admission was the source of four generations of transmission to 76 case-patients, including 12 healthcare workers and several hospital visitors. Four (5%) case circumstances met the superspreading definition. Superspreading appeared to be associated with older age (mean 56 vs. 44 years), case fatality (75% vs. 16%, p = 0.02, Fisher exact test), number of close contacts (36 vs. 0.37) and attack rate among close contacts (43% vs. 18.5%, p < 0.025). Delayed recognition of SARS in a hospitalized patient permitted transmission to patients, visitors, and healthcare workers. Older age and number of contacts merit investigation in future studies of superspreading.