Effectiveness of 10-year vaccination (2001-2010) on Hepatitis A in Tianjin, China.

Vaccination is an effective strategy to prevent and control the transmission of hepatitis A. Hepatitis A immunization program has been taken into effect since 2001 in Tianjin, China. This study evaluated the effectiveness of strategies in the prevention and control of hepatitis A. Data of serological survey, annual hepatitis A incidence, immunization coverage and the positive rate of hepatitis A IgG before and after the immunization program in residents under 15 years old were used to do the analysis. The results indicated that hepatitis A vaccine induced a striking decrease of hepatitis A incidence and a significant increase in the positive rate of anti-HAV IgG among the children younger than 15 years old. Hepatitis A vaccination in children was proved to be effective in the prevention and control of hepatitis A in Tianjin, China.

[Current status of hepatitis B immunization and strengthened immune memory among first-year middle school students in Tianjin].

OBJECTIVE: To investigate the immunization status of hepatitis B vaccine who were inoculated at birth, HBV infections and the vaccine booster effect in the first-year middle school students (12 - 14 years old). METHODS: A cluster, stratified simplified random sampling method was administrated. The sample size was at least 218, which was calculated by Epi Info 3.3.2 software at 53% the minimum acceptable anti-HBs positive rate and 95% confidence level. A total of 250 and 236 students participated in the infection status and booster immunization effects investigation. The HBsAg, anti-HBs and anti-HBc IgG were detected by Enzyme-linked immunosorbent assay (ELISA). HBV DNA was detected by fluorescence quantitative PCR, and the diagnostic test kit were produced respectively by ABBOTT, Diasorin and Beijing Wantai Biological Pharmacy Enterprise Co. RESULTS: For the immunization status before booster: the positive rate of anti-HBs was 62.80% (157/250), the GMT was 73.79 IU/L; the currently HBV infection rate (HBsAg and anti-HBc positive) was 2.80% (7/250). After injection, the anti-HBs positive rate was 94.92% (224/236). Compared with the before booster results, the significant difference was observed (χ(2) = 73.92, P = 0.00). The GMT was 521.15 IU/L, comparing with the before booster results, there was significant difference (t = 15.98, P = 0.00). The anti-HBs conversion rate (from negative to positive) was 91.86% (79/86) after immune-enhancement; of which, 11 students got the second dose of booster vaccine who are no-responders after first injection, in addition 8 students got the anti-HBs. CONCLUSION: It is an effective method to put the first-year middle school students into the immune-enhancement program, so as to improve the immunization memory effect and avoid the loss of protective antibodies.

[Study on the report criteria and focus management mode of the virus hepatitis cases in Tianjin].

OBJECTIVE: To establish the focus management mode and the report criteria more perfectly for the virus hepatitis cases, especially for the hepatitis B. METHODS: One district was set as the research area, in which there was enough cases resource and relatively separated from the other districts, then a first or second-class hospital was appointed to take the cases focus diagnosis, report and management. RESULTS: The focus hospitals had reported 97% (323/331) of cases in the research area between June,2007 and June,2008; moreover,the rate in establishing case-card was 97.21% (314/323), as compared with that in period of 2007 (261), the cases reported declined 61.30% in the first half year of 2008 (101). CONCLUSION: It should be an imperative situation to establish a report criteria and management mode for virus hepatitis (hepatitis B), however it is necessary to have more supports from health administrations.

[A study on the influenza surveillance program in Tianjin, 2004].

OBJECTIVE: To explore the trend of influenza epidemics, predominate strains of the virus in Tianjin city and to analyze the economic impact of vaccine-based interventions for the prevention and control of influenza. METHODS: Data on epidemiological studies and on virus surveillance was gathered. Monte Carlo mathematical simulation modelwas used for data analyses. RESULTS: From 29, December, 2003 to 2, January, 2005, the proportion of influenza-like infection cases was accounted for 8.93% of the total number of patients from the outpatient departments of 4 general hospitals in Tianjin. The proportion reached its peak from November to February and it was accounted for 9.39% in epidemic period, which was significantly different from that in the non-epidemic period (u = 15.53, P< 0.05). There was 56 strains of influenza virus isolated in which 45 were indentified as A(H3N2) and 11 as B with a total positive rate as 13.21%. Predominant strain was found bing type A(H3N2). The positive rate was 15.41% in the epidemic period, which was significantly different from that in the non-epidemic period (u = 2.519, P < 0.05). The cost per visit ranged from 475.93 to 581.69 Yuan (RMB) with an average cost of 528.81 Yuan. When the attack rate increased to 30 percent, the positive mean net returns would have been 24 million Yuan among the 0-19 age group. CONCLUSION: Influenza did not seem to be prevalent in Tianjin from 29, December, 2003 to 2, January, 2005. The main type of influenza was type A(H3N2). It is necessary to pay attention to the all-year round surveillance program due to the transformation of influenza type A and the slight increase of incidence in summer.

[Epidemiological characteristics of severe acute respiratory syndrome in Tianjin and the assessment of effectiveness on measures of control].

OBJECTIVE: To analyze the epidemiologic characteristics of severe acute respiratory syndrome (SARS) and to evaluate the effectiveness on its major control measures in Tianjn. METHODS: Adopting two case reports 1 and 2, designed by the Tianjin Centers for Disease Control and Prevention to develop a unified case-tracing table including the map of the distribution of close contacts to SARS patients. With those methods, investigation on patients and their close contacts at hospital wards, families, communities and institutions of the patients were carried out. RESULTS: From April 13 through May 8, 2003, there were 175 SARS cases including imported ones, were identified with an incidence rate of 1.9 cases per 100,000. Among them, 14 died with a fatality of 8.0%. The whole process of epidemic in Tianjin was less than one month with the following features: (1) 93.7% of the total SARS cases in Tianjin were directly or indirectly transmitted by a super-spreader. (2) 68.6% of the total SARS patients were concentrated in 3 hospitals A, B and C which was menifastated in 'clustering'. Through study on the rest of the SARS patients, results showed that 16.8% of them were transmitted through family close contact and 2.3% due to contact to colleagues. However, 12.6% of the patients were not able to show evidence that they had any contact to a diagnosed SARS patient. At the early stage of the epidemic, a number of medical practitioners were infected, taking up 38.2% of the total SARS cases. Among the total number of 1 975 medical workers who participated in the SARS medical cares and treatments, 3.4% of them got infected. During the outbreak, all index cases and chains of transmission seemed to be clear, with only 3 patients not able to be traced for the source of infection, taking up 2% of the total SARS patients in Tianjin. Among the 10 index cases, only the super spreader and another one index case transmitted the virus to their contacts but the rest of index cases did not cause any secondary infection. CONCLUSION: Though SARS is clinically severe and can be spreaded quickly, the epidemic can be under control within a short period of time if chains of SARS transmission are broken down and effective measures as isolation and quarantine against patients as well as underscoring awareness among the publics in a scientific way, being carried out.