A study on the influenza surveillance program in Tianjin, 2004 / 中华流行病学杂志

<p><b>OBJECTIVE</b>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.</p><p><b>METHODS</b>Data on epidemiological studies and on virus surveillance was gathered. Monte Carlo mathematical simulation modelwas used for data analyses.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>

Epidemiological characteristics of severe acute respiratory syndrome in Tianjin and the assessment of effectiveness on measures of control / 中华流行病学杂志

<p><b>OBJECTIVE</b>To analyze the epidemiologic characteristics of severe acute respiratory syndrome (SARS) and to evaluate the effectiveness on its major control measures in Tianjn.</p><p><b>METHODS</b>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.</p><p><b>RESULTS</b>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.</p><p><b>CONCLUSION</b>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.</p>