Epidemiological characteristics and serum antibody detection of a COVID-19 aggregated outbreak in vaccinated population / 中华预防医学杂志

An epidemiological investigation was conducted on a cluster epidemic of COVID-19 in the vaccinated population in Beijing in 2022, and serum samples were collected from 21 infected cases and 61 close contacts (including 20 cases with positive nucleic acid in the isolation observation period). The results of antibody detection showed that the IgM antibody of two infected persons was positive, and the IgG antibody positive rates of patients who were converted, not converted to positive and infected persons were 36.84% (7/19), 63.41% (26/41) and 71.43% (15/21), respectively. About 98.78% of patients had been vaccinated with the SARS-CoV-2 inactivated vaccine. The positive rate of IgG antibody in patients immunized with three doses of vaccine was 86.00% (43/50), which was higher than that in patients with one or two doses [16.12% (5/31)]. The antibody level of M (Q1, Q3) in patients immunized with three doses was 4.255 (2.303, 7.0375), which was higher than that in patients with one or two doses [0.500 (0.500, 0.500)] (all P values<0.001). The antibody level of patients who were vaccinated less than three months [7.335 (1.909, 7.858)] was higher than that of patients vaccinated more than three months after the last vaccination [2.125 (0.500, 4.418)] (P=0.007). The positive rate and level of IgG antibody in patients who were converted to positive after three doses were 77.78% (7/9) and 4.207 (2.216, 7.099), respectively, which were higher than those in patients who were converted after one or two doses [0 and 0.500 (0.500, 0.500)] (all P values<0.05).

Analysis on infection sources and transmission chains of three outbreaks caused by 2019-nCoV Omicron variant in Beijing, China / 中华流行病学杂志

Objective: To investigate the infection sources and the transmission chains of three outbreaks caused by 2019-nCoV Omicron variant possibly spread through cross-border logistics in Beijing. Methods: Epidemiological investigation and big data were used to identify the exposure points of the cases. Close contacts were traced from the exposure points, and the cases' and environmental samples were collected for nucleic acid tests. Positive samples were analyzed by gene sequencing. Results: The Omicron variant causing 3 outbreaks in Beijing from January to April, 2022 belonged to BA.1, BA.1.1 and BA.2. The outbreaks lasted for 8, 12 and 8 days respectively, and 6, 42 and 32 cases infected with 2019-nCoV were reported respectively. International mail might be the infection source for 1 outbreak, and imported clothes might be the infection sources for another 2 outbreaks. The interval between the shipment start time of the imported goods and the infection time of the index case was 3-4 days. The mean incubation period (Q1, Q3) was 3 (2,4) days and the mean serial interval (Q1, Q3) was 3 (2,4)days. Conclusions: The 3 outbreaks highlighted the risk of infection by Omicron variant from international logistics-related imported goods at normal temperature. Omicron variant has stronger transmissibility, indicating that rapid epidemiological investigation and strict management are needed.

A real-world study of the efficacy and safety of sofosbuvir and velpatasvir in the treatment of HCV-infected patients in a county in northern China / 中华肝脏病杂志

Objective: To evaluate the real-world efficacy and safety of sofosbuvir and velpatasvir (SOF/VEL) tablets in the treatment of Chinese patients with chronic HCV infection. Methods: An open-label, single-center, prospective clinical study was conducted in a county in northern China. A total of 299 cases were enrolled. Of these, 161 cases with chronic hepatitis C and 73 cases with compensated cirrhosis received SOF/VEL for 12 weeks. 65 cases with decompensated cirrhosis received SOF/VEL combined with ribavirin for 12 weeks (22 cases) or SOF/VEL for 24 weeks (43 cases). Virological indicators, liver and renal function indexes, and liver stiffness measurement were detected at baseline, the fourth week of treatment, the end of treatment, and the 12-weeks of follow-up. Adverse reactions and laboratory abnormalities were observed during the course of treatment . The primary endpoint was undetectable rate of HCV RNA (SVR12) at 12 weeks of follow-up with the use of modified intention-to-treat (mITT) approach. Measurement data between two groups were compared using t-test. One Way ANOVA was used for comparison between multiple groups. Enumeration data were analyzed by chi-square test or Fisher's exact test. Results: 291 cases had completed treatment. HCV RNA was undetectable after 12 weeks of follow-up, and the SVR12 rate was 97.3% (95% confidence interval: 95.4%-99.3%). Among them, 97.4% of genotype 1b, 96.4% of genotype 2a, and 100% of those with undetected genotype achieved SVR12. The SVR12 rates in patients with chronic hepatitis C, compensated and decompensated liver cirrhosis were 98.1%, 98.6% and 93.8%, respectively. An improvement in alanine aminotransferase, aspartate aminotransferase and other liver biochemical indicators accompanied with virological clearance and reduced liver stiffness measurement was observed in patients with compensated cirrhosis, with statistically significant difference. There was no significant abnormality in renal function before and after treatment. The most common adverse reactions were fatigue, headache, epigastric discomfort and mild diarrhea. The overall adverse reactions were mild. One patient died of decompensated liver cirrhosis combined with massive upper gastrointestinal bleeding, which was unrelated to antiviral treatment. Four patients discontinued treatment prematurely due to adverse events. Relapse was occurred in four cases, and drug-resistance related mutations were detected in three cases. Conclusion: Sofosbuvir and velpatasvir tablets in Chinese HCV-infected patients with different genotypes, different clinical stages or previously treated with pegylated interferon combined with ribavirin resulted in higher SVR12, indicating that the treatment safety profile is good.

Survey of possible aerosol transmission of a COVID-19 epidemic caused by 2019-nCoV Delta variant / 中华流行病学杂志

Objective: To investigate the epidemiological characteristics and the transmission chain of a family clustering of COVID-19 cases caused by severe acute respiratory 2019-nCoV Delta variant in Changping district of Beijing. Methods: Epidemiological investigation was conducted and big data were used to reveal the exposure history of the cases. Close contacts were screened according to the investigation results, and human and environmental samples were collected for nucleic acid tests. Positive samples were analyzed by gene sequencing. Results: On November 1, 2021, a total of 5 COVID-19 cases caused by 2019-nCoV Delta variant were reported in a family detected through active screening. The infection source was a person in the same designated isolation hotel where the first case of the family cluster was isolated from 22 to 27, October. The first case was possibly infected through aerosol particles in the ventilation duct system of the isolation hotel. After the isolation discharge on October 27, and the first case caused secondary infections of four family members while living together from October 27 to November 1, 2021. Conclusion: 2019-nCoV Delta variant is prone to cause family cluster, and close attention needs to be paid to virus transmission through ventilation duct system in isolation hotels.

An investigation on serum antibody level of varicella-zoster virus in healthy population in Beijing / 中华预防医学杂志

Objective: To assess the level and trend of varicella-zoster virus (VZV) antibody among healthy population in Beijing in 2017, after the five-year implementation of the two doses varicella vaccination strategy in 2012, and to provide evidence for scientific evaluation of immunization strategy. Methods: A total of 2 144 subjects in ten age groups from 8 districts of Beijing city were recruited in this study using cross-sectional survey based on multi-stage cluster random sampling method. Serum samples were collected and VZV antibody was detected by ELISA. The influencing factors of antibody concentration and positive rate were analyzed and compared with the study in 2012. The antibody concentration and antibody positive rate were analyzed by nonparametric test and χ² test respectively. Results: The ratio of subjects with registered residence in Beijing city to other provinces was 1∶1. The ratio of male to female was 1∶1.08. The median concentration of VZV antibody was 341.4 (78.6, 1 497.8) mIU/ml, and the total antibody positive rate was 71.1% (1 524/2 144). There were significant differences in antibody positive rate (χ²=736.39, P<0.01) and antibody concentration (χ²=740.34, P<0.01) among different age groups. The antibody positive rate generally increased with age (χ²trend=7.32, Ptrend<0.01). Among 862 children under 14 years old, the antibody positive rate of two doses vaccination 72.8% (182/250) was significantly higher than that of one dose vaccination 51.9% (154/297) (χ²=25.14, P<0.01). There was significant difference between 1-4 years old group (χ²=11.71, P<0.01) and 10-14 years old group (χ²=5.95, P=0.02), but not in 5-9 years old group (χ²=3.00, P=0.07). Compared with the study in 2012, the antibody positive rate increased in 5-9 years old group (χ²=14.35, P<0.01) and decreased in 1-4 years old group (χ²=11.51, P=0.01) in 2017. Conclusion: The recommended varicella booster vaccination has significantly improved the VZV antibody level of children in Beijing city. In the future, it is necessary to explore a more optimized two doses varicella vaccination schedule for children in combination with epidemiological evidence.

Investigation on measles cases of new genotype D8 in Beijing, 2013 / 中华流行病学杂志

<p><b>OBJECTIVE</b>To investigate the epidemiological characteristics of measles cases of new genotype D8 in Beijing from January to June, 2013.</p><p><b>METHODS</b>Epidemiological survey and descriptive analysis was conducted.</p><p><b>RESULTS</b>661 suspected measles were reported from January to June, 2013. 416 were confirmed measles cases by serology and etiology detection. 28 measles cases were caused by genotype D8 measles virus by genotype identification. There were 2 measles outbreak including 14 cases and 14 sporadic cases. The incidence peak was during April and May. 25 cases (89.3%, 25/28) occurred in downtown and suburban districts. 22 cases (78.5%, 22/28) were adults aged 15-39 years and 19 cases (67.9%, 19/28) were migrant population. 12 cases (85.7%, 12/14) in outbreak were migrant population working in clothing sales. There was epidemiological association between 2 outbreaks.</p><p><b>CONCLUSION</b>Measles cases of genotype D8 were found for the first time in Beijing. Genotype D8 virus mainly infected migrant adults and caused local outbreak and endemic.</p>

Analysis of measles immunity level in persistent populations in Beijing, 2012 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To analyze the measles immunity level of persistent population in Beijing.</p><p><b>METHODS</b>A total of 2125 objects from 10 age groups, who had been living in Beijing for over 6 months, were selected from urban and rural areas in Beijing in 2012. Demographic characteristics, history of measles and vaccine immunization were investigated by questionnaire. 5 ml blood sample of each subject was collected, and the Measles IgG antibody was measured by ELISA assay.</p><p><b>RESULTS</b>Positive rate of measles antibody was 84.71% (1800/2125) and standardized positive rate was 88.07% . Median of antibody was 960.46 IU/L. Positive rate and median of measles antibody were significantly different between population from different age groups (χ(2) = 341.60, P < 0.01; H = 216.27, P < 0.01). Antibody positive rate and median were lowest in the <1 year age group, which were separately 43.06% (90/209) and 185.80 IU/L; and highest in the 1-4 (97.31% (181/186) and 2448.81 IU/L) and 5-9 years age group (96.46% (218/226) and 1910.72 IU/L). The range of antibody positive rate and median in adults of ≥ 15 years were 81.98%-90.14% and 744.38-1474.84 IU/L. Antibody positive rate and median in persistent population, which were separately 82.45% (883/1071) and 899.82 IU/L, were lower than those in migrant population, which were 87.00% (917/1054) and 166.19 IU/L, respectively (χ(2) = 8.51, P < 0.01;U = 538 704.00, P < 0.01). Antibody positive rate and median in population with vaccination history, which were separately 91.95% (891/969) and 1443.11 IU/L, were higher than those population without vaccination history and people whose history unknown (32.95% (57/173) , 127.33 IU/L; 86.67% (852/983) , 923.73 IU/L). The difference showed statistical significance (χ(2) = 399.92, P < 0.01; H = 202.11, P < 0.01).</p><p><b>CONCLUSION</b>Among the persistent population in China, measles antibody level among the children aging 1-9 years old was high enough to prevent outbreak and epidemic of measles. However, we should try our best to strengthen the measles antibody level among the babies younger than 1 year old and the migrant population aging between 15 and 40 years old.</p>

Survey on seroepidemiological status and vaccine coverage of hepatitis B among children in Chaoyang district of Beijing in 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore seroepidemiological status and vaccine coverage of hepatitis B in children aging under 15 years old in Chaoyang district of Beijing.</p><p><b>METHODS</b>A total of 1602 children aging under 15 years old, residents or floating population who had lived here more than six months, were randomly selected by multistage cluster sampling, from Chaoyang district of Beijing in year 2010. The demographic information and vaccine coverage of hepatitis B vaccine (HepB) were collected by self-designed questionnaire.5 ml blood was collected from each subject and the serum HBsAg, anti-HBs and anti-HBc were detected by Abbott microparticle enzyme-linked immunoassay. Those whose HBsAg was positive were then tested HBeAg and anti-HBe. The positive rate of hepatitis B indicators and coverage rate of HepB in different population were compared.</p><p><b>RESULTS</b>The positive rate of HBsAg, anti-HBs and anti-HBc were 0.56% (9/1602), 64.17% (1028/1602) and 2.12% (34/1602), respectively; while the age standardized rates were separately 0.57%, 66.36% and 1.98%; and the gender-adjusted rates were 0.56%, 64.23% and 2.12% respectively. The positive rate of anti-HBs was statistically significant (χ(2) = 165.445, P = 0.000). The positive rate of anti-HBs was up to 90.73% (235/259) among 1-2 years old children, followed by 76.22% (141/185) among 13 - 15 years old children, 67.21% (166/247) among 3 - 4 years old children, 61.22% (150/245) among 9 - 10 years old children, 60.68% (142/234) among 11 - 12 years old children, 49.05% (103/210) among 5 - 6 years old children and 40.99% (91/222) among 7 - 8 years old children. The average coverage rate of HepB was 90.44% (1371/1516), separately 93.76% (661/705) in residents and 87.55% (719/811) in floating population. The difference was statistically significant (χ(2) = 16.829, P = 0.000).</p><p><b>CONCLUSION</b>HBsAg positive rate in children under 15 years old in Chaoyang district of Beijing dropped to less than 1% and the coverage rate of HepB had reached over 90%. It is suggested that we should pay more attention to increase the coverage rate of HepB among floating children under 15 years old.</p>

Study of immunogenicity after primary vaccination by different sequential program of inactivated poliovirus vaccine and oral poliovirus vaccine / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate immunogenicity after primary vaccination by different sequential program of inactivated poliovirus vaccine (IPV) and oral poliovirus vaccine (OPV).</p><p><b>METHODS</b>Children of 2 months old (60-89 days) selected in Beijing were assigned to 4 groups, 1 dose IPV plus 2 doses OPV (I-O-O, 122 children), 2 doses IPV plus 1 dose OPV(I-I-O, 103 children), 3 doses IPV (I-I-I, 114 children), and 3 doses OPV (O-O-O, 106 children), and were vaccinated at the age of 2, 3, 4 months. Polio neutralizing antibody titers against poliovirus types 1, 2, and 3 were tested and protective rates were calculated before the 1st dose, after the last dose, and after the 1st and 2nd dose of IPV.</p><p><b>RESULTS</b>After the primary immunization, geometric mean titers (GMT) of polio neutralizing antibody titers against poliovirus types 1, 2, and 3 were 788.32, 738.42 and 631.17 in O-O-O group, 212.02, 262.30 and 537.52 in I-I-I group, 940.35, 929.72 and 940.35 in I-O-O group and 901.09, 1102.68 and 1110.12 in I-I-O group (F values were 47.71, 53.84, and 9.81 respectively, all P values<0.01). The protective rate of three types among each group was 98.1% (104/106)-100.0% and the difference was not statistically significant (P>0.05). After the 1(st) dose of IPV, the GMT were 18.88, 37.77, 24.64 and the protective rate was 82.6% (122/138)-96.4% (133/138); after the 2nd dose of IPV, GMT were 177.03, 168.25, 321.86 and the protective rate was 99.1% (108/109)-100.0% (109/109) in antibody types 1, 2 and 3, respectively.</p><p><b>CONCLUSION</b>GMT of polio neutralizing antibody titers against poliovirus is higher after vaccination by sequential program of IPV and OPV than that by IPV or OPV 3-doses program. High level of protective rate after 2 doses of IPV in I-I-O group may lead to better protection from vaccine associated paralytic poliomyelitis (VAPP). Sequential program of IPV and OPV can be used to maintain high level of herd immunity and to prevent VAPP, and the I-I-O sequential program should be the first choice.</p>

Prevalence of hepatitis B in Chaoyang district, Beijing in 2010 / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the prevalence of hepatitis B infections and carrier status among general population in Chaoyang district, Beijing in 2010.</p><p><b>METHODS</b>From May to December 2010, 14 491 subjects over 12 months old were selected by multistage random cluster sampling method from residents in Chaoyang district, Beijing. Five millilitre venous blood specimens were collected from these subjects to test hepatitis B virus antigens and antibodies. Status of hepatitis B infections were analyzed in different age, sex and registered permanent residence groups.</p><p><b>RESULTS</b>The overall positive rate of surface antigen (HBsAg) was 2.66% (383/14 410). The lowest rate of 0.56% (9/1603) was found in the 1 to 14 years old group and the 35 to 44 years old group had the highest rate of 4.27% (92/2154). The rate in subjects younger than 24 years old was 1.03% (31/2986). The overall positive rate of surface antibody (anti-HBs) was 40.21% (5798/14 421). The highest positive rate of anti-HBs (80.59%, 407/505) was found in the 1 to 4 years old group. The overall positive rate of core antibody (anti-HBc) was 30.26% (4364/14 424). The overall hepatitis B virus infection rate was 30.32% (4364/14 393). For male and female groups, the positive rates of HBsAg were 2.93% (179/6108) and 2.44% (202/8287) respectively (χ² = 3.32, P > 0.05); anti-HBs were 41.93% (2563/6113) and 38.96% (3231/8293) respectively (χ² = 12.88, P < 0.01); and anti-HBc were 31.39% (1919/6114) and 29.39% (2438/8295) respectively (χ² = 6.65, P = 0.01). For local residents group and mobile population group, the positive rates of HBsAg were 2.46% (283/11 510) and 3.60% (98/2719) respectively (χ² = 11.08, P < 0.01); anti-HBs were 37.11% (4293/11 568) and 53.07% (1445/2723) respectively (χ² = 233.51, P < 0.01); and anti-HBc were 30.83% (3567/11 570), and 28.41% (774/2724) respectively (χ² = 6.08, P < 0.05).</p><p><b>CONCLUSION</b>The positive rate of HBsAg in population younger than 24 years old has reached a relatively low level. The mobile population has significantly higher positive rate of HBsAg than local residents, indicating the need for enhancing prevention and control measures for hepatitis B for the mobile population and local residents over 25 years old.</p>

Study on family aggregation and risk factors of hepatitis B virus transmission in Chaoyang district, Beijing / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the family aggregation and risk factors of hepatitis B virus (HBV) transmission in Chaoyang district of Beijing.</p><p><b>METHODS</b>A total of 5266 families were randomly selected for the multi-stage cluster sampling study in Chaoyang district of Beijing in 2010. The family members who aged between 1 and 70 years old and lived constantly in Beijing for over half a year, were recruited as subjects. There were 14 491 subjects in total, including temporary residents who did not have Beijing household account, except foreigners. 5 ml venous blood was drawn from every subject. A self-designed questionnaire was used to collect the basic information of the population and the risk factors of the hepatitis B transmission. Microparticle enzyme-linked immunoassay was applied to test five indicators of hepatitis B. Negative binomial distribution test was used among the HBsAg positive families to calculate the family aggregation rate of hepatitis B. Single factor analysis and multi-factor logistic regression model were used to analyze the risk factors of HBV transmission.</p><p><b>RESULTS</b>In all, 308 out of 5266 families had HBsAg positive members, accounting for 5.85%.383 out of 14 410 subjects were HBsAg positive, rating at 2.66%. The HBsAg positive rate among subjects under 14 years old was the lowest, at 0.56% (9/1603); and the positive rate among subjects aging between 35 and 44 years old was the highest, at 4.27% (47/1029). Negative binomial distribution test showed that the family aggregation rate of HBV infection was 7.66% (χ² = 15.10, P < 0.05). The analysis of family aggregation of HBsAg positive showed that 17.39% (8/46) of the transmission was from father to child, 13.04% (6/46) was from mother to child, 30.44% (14/46) was between couples, and another 39.13% (18/46) was between siblings or other relatives. Both single factor analysis and multi-factor logistic regression analysis showed that hepatitis B positive family members (OR = 5.40, 95%CI: 5.24 - 5.55), hepatitis B positive friends and colleagues (OR = 1.55, 95%CI: 1.11 - 1.99) and blood donation and transfusion history (OR = 1.96, 95%CI: 1.76 - 2.15) were the risk factors of HBV infection.</p><p><b>CONCLUSION</b>HBV transmission showed family aggregation in Beijing, however, the risk factors needed further studies.</p>

The epidemiological impact of varicella vaccination in kindergartens, primary and secondary schools in Beijing / 中华预防医学杂志

<p><b>OBJECTIVE</b>To study the epidemiological impact of varicella vaccine vaccination on kindergartens and school children in Beijing.</p><p><b>METHODS</b>According to "China Information System for Diseases Control and Prevention", the reported clinical diagnosis varicella cases were tracked in kindergartens, primary and secondary schools whose onset date were from 2008 to 2010. Epidemiological survey was conducted and epidemiological features were analyzed.</p><p><b>RESULTS</b>A total of 21 474 varicella cases were investigated: 55.3% (11 883 cases) had been vaccinated by varicella vaccine. Of cases with definite immunization history, interval between vaccination date and onset date were from 30 days to 1 year accounted for 3.4% (286/8510), 1 to 3 years accounted for 18.2% (1551/8510), 3 to 5 years accounted for 28.6% (2431/8510), 5 to 10 years accounted for 34.3% (2916/8510) (left-closed right-open interval); The peak age of onset was 4 years old in cases without immunization history, which was 6 years old in cases with immunization history; The proportion of cases with immunization history (≥ 30 days) had increased from 42.4% (2862/6754) in 2008 to 56.3% (4327/7679) in 2010. The cases with no fever had a higher proportion (54.9%, 6413/11 679) of immunization history (≥ 30 days) than cases with fever (47.7%, 4533/9500) (P < 0.01); The cases with rashes less than 50 had a higher proportion (57.4%, 8045/14 020) of immunization history (≥ 30 days) than cases with rashes more than 50 (40.2%, 2902/7216) (P < 0.01).</p><p><b>CONCLUSION</b>Varicella vaccine delays the peak age of onset, alleviates the symptoms. The current immunization strategy can not block varicella spread in kindergartens, primary and secondary schools.</p>

A survey on serological epidemiology of influenza A (H1N1) 2009 in Beijing / 中华流行病学杂志

Objective To investigate the immunological level against influenza A (H1N1)2009 in Beijing and provide evidence to evaluate the developing trend of the disease. Methods Between Nov. 27,2009 and Dec. 23,2009, subjects were randomly selected from patients in hospitals (infectious and respiratory diseases related departments were excluded) ,volunteers in blood donation center and healthy subjects attending the physical examination center. Questionnaire survey was conducted and serum samples were collected to detect the hemagglutination-inhibition (HI) antibody against influenza A(H1N1) 2009 virus. Results 856 subjects participated in this survey, and 127 showed positive HI antibody to this pandemic virus. The proportions of sero-positivity among 0-5 ,was no significant difference in the sero-positivity between males and females (P=0.693). The analysis, factors as age, acute respiratory symptoms and the rate of pandemic (H1N1) 2009 vaccination were significantly associated with sero-positivity of HI antibody to the influenza A (H1N1) 2009 virus. Conclusion Above 15% of the population in Beijing showed protective antibody against influenza A (H1N1) 2009 virus, indicating the development of immunological barrier to this disease had been formed, to some extent.

Etiological characteristics of influenza A (H1N1) 2009 virus in Beijing / 中华流行病学杂志

Objective To analyze the results of detection on influenza A (H1N1) 2009 virus in Beijing from May 2009 to December 2009 and to understand the epidemiologic characteristics during the pandemic period. Methods The study was conducted from the May 1 to December 27,2009. A total of 101 852 throat swab samples were detected with the real-time RT-PCR assay by the Beijing Network Laboratory. Data was statistically analyzed. Results 9843 samples showed influenza A (H1N1) 2009 positive, with an overall positive rate as 9.66%. In terms of the positive rates, they were 2.85% from May to June, 3.32% from July to August and 8.35% from September to October. The peak month fell in November (29.67%) and December (24.33%). The positive rates among the following subpopulations were: 8.40% among the suspected cases, 4.75% among close contact cases, 11.46% among the influenza-like illness cases and 7.33% among the cluster cases with fever. Positive cases mainly fell in age groups 5-14 and 15-24. The ratio of male to female was 1.5:1.Conclusion During the pandemic period of influenza A (H1N1) 2009, positive cases gradually increased during May to November but slowly decreasing in December.

Estimation on the real number of novel influenza A (H1N1) cases, Beijing, 2009 / 中华流行病学杂志

Objective To estimate the real number of novel influenza A(H1N1 ) infection in Beijing, 2009. Methods A multiplier model (Impact 2009 v 1.0 software) based on Monte Carlo approach was used to estimate the real number of novel influenza A (H1N1 ) based on the number of influenza-like illness (ILI) cases, novel influenza A(H1N1 ) positive rate among ILI cases and rate on clinical visit of ILIs in secondary and tertiary hospitals. Results There were 1.80 million (90%CI: 1.46-2.30) estimated novel influenza A (H1N1) cases in 2009 in Beijing with the rate of infection as 11.0%. One reported case would represent 167 real infections. The highest age groups of infection were 0-4 years and 5-14 years, being 32.5% and 33.3%, respectively. Conclusion Laboratory-confirmed infections with novel influenza A (H1N1 ) only represented a fraction of the total cases in a population, suggesting that it was imperative to estimate the real number of novel influenza A (H1N1) infection.

Analysis of adverse events following 2009 influenza A (H1N1) vaccinoprophylaxis in Beijing / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the safety of 2009 influenza A (H1N1) vaccine based on mass immunization initiative in Beijing.</p><p><b>METHOD</b>There were 2 113 280 people were vaccinated during September to December 2009. The information of adverse events following immunization (AEFI) was collected through surveillance system, and descriptive methodology was used for data analysis.</p><p><b>RESULTS</b>A Total of 612 AEFI cases were reported, among which there were 321 vaccine reaction cases following immunization, 203 coincidental illness cases, 82 psychogenic reaction cases, and 6 pending cases. The rates of rare reactions and common reactions associated with vaccination were respectively 5.54/100 000 (117/2 113 280) and 9.65/100 000 (204/2 113 280). The rate of serious rare reaction was 0.19/100 000 (4/2 113 280). The rates of vaccine reactions in urban, suburb and county were 16.87/100 000 (36/213 519), 17.81/100 000 (187/1 049 817) and 11.53/100 000 (98/849 944), respectively. The rates of rare reaction and common reaction in different age groups were between 3.65/100 000 (6/164 604) to 8.99/100 000 (27/300 176), and between 0.61/100 000 (1/164 604) to 22.06/100 000 (85/385 275). The 117 rear vaccine reaction cases were mainly allergic reaction (107 cases), and the 204 common vaccine reaction cases were mainly fever (176 cases). There were 91.90% (295/321) vaccine reactions occurred within 24 hours of administration, and all cases had improved consequence.</p><p><b>CONCLUSION</b>The mostly symptoms of AEFI cases during the period of 2009 influenza A (H1N1) vaccinoprophylaxis were anaphylaxis and fever. The types of adverse reactions and the level of serious events are consistent with the anticipation. There were no rear or new events occurred.</p>

Study on the cellular and humoral immunity effect of recombinant Chinese hamster ovary cell hepatitis B vaccine in adults / 中华预防医学杂志

<p><b>OBJECTIVE</b>To evaluate the cellular and humoral immunity effect of 10 µg and 20 µg recombinant Chinese hamster ovary (CHO) cell hepatitis B vaccine in adults by randomized double-blind controlled trials.</p><p><b>METHOD</b>A total of 642 adults aged 18 - 45 years old, non-vaccinated against hepatitis B, and hepatitis B five blood indicators negative were selected as the study subjects. The study subjects were randomly divided into two groups and each group had 321 subjects. The subjects were given 10 µg and 20 µg recombinant CHO hepatitis B vaccination respectively by 0, 1st, 6th month schedule. Blood sample was collected from each study subject one month after the second dose vaccination. The anti-HBs level was detected by Abbott chemiluminescence detection method (I2000) to evaluate humoral immunity status. Of all the study objects, 153 cases were randomly selected by the Excel random function. Their blood samples were collected and Lymphocyte were separated to detect the IL-4 and IFN-γ levels in vitro by enzyme-linked immunospot (ELISPOT) method to evaluate the cellular immunity status.</p><p><b>RESULTS</b>The anti-HBs seroconversion rates in 10 µg and 20 µg dose group were 88.8% (285/321) and 95.3% (306/321) respectively, and 95%CI were 85.4% - 92.2% and 93.0% - 97.6% respectively. The spot forming cell (SFC) of IL-4 of the 20 µg-dose group (x(-) = 20.31) were significantly higher than the 10 µg-dose group (x(-) = 8.19, t = 3.27, P < 0.01). With the increasing of anti-HBs titer, the SFC of IL-4 also went up significantly. There was a positive correlation between SFC of IL-4 and anti-HBs (Spearman correlation coefficient = 0.538, P < 0.0001). No significant difference was found for IFN-γ SFC in two groups (10 µg group: x(-) = 1.49; 20 µg group: x(-) = 0.86; t = 1.83, P > 0.05).</p><p><b>CONCLUSION</b>The humoral and cellular immune effects of 20 µg recombinant CHO hepatitis B vaccine are better than that of the 10 µg recombinant CHO hepatitis B vaccine.20 µg recombinant CHO hepatitis B vaccine should be chosen as the adult's hepatitis B prevention vaccine.</p>

Pandemic influenza A (H1N1) virus infection factors among healthcare workers - a case-control study / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore factors related to pandemic influenza A (H1N1) virus infection among healthcare workers.</p><p><b>METHODS</b>H1N1 influenza confirmed cases of health workers in hospital of Beijing from Aug 30th 2009 to Jan 31st 2010 were included. A 1:4 matched case-control study was conducted with 54 healthcare workers who were infected by influenza A(H1N1) virus and 216 matched controls who were not infected. Face-to-face interview with questionnaires was used to collect information of work and family aspects of the study participants. Conditional logistic regression was used to analyze the H1N1 infection factors.</p><p><b>RESULTS</b>The age was 29.6 ± 7.4 years old and male subjects accounted for 17.4% (47/270). There were 5.6% (3/54) and 34.4% (74/216) of the cases get the influenza A (H1N1) vaccine immunization separately in the case group and control group. Among 18.5% (10/54) and 40.1% (88/216) of the cases and controls used high protection level masks during the epidemic. Besides, 33 (61.1%)and 161 (74.5%) cases lengthening the time of mask wearing separately. There were 13 (24.1%) and 85 (39.4%) cases using disposable tissue to clean hands in the case group and control group, 24 (44.4%) and 46 (21.3%) cases feel they were much easier to get infected in respiratory disease than others based on experience in the case and control group. Univariate analysis showed that factors such as using disposable tissue to clean hands (OR = 0.15, 95%CI = 0.04 - 0.57), lengthening the time of mask wearing (OR = 0.43, 95%CI = 0.20 - 0.92), using high protection level masks (OR = 0.26, 95%CI = 0.11 - 0.58), getting influenza A (H1N1) vaccine immunization (OR = 0.04, 95%CI = 0.01 - 0.32), much easier to get infected in respiratory disease than others based on experience (OR = 2.85, 95%CI = 1.44 - 5.62), were all associated with influenza A (H1N1) infection. Results of multivariate logistic regression analysis showed that variables such as history of influenza A (H1N1) virus immunization (OR = 0.18, 95%CI = 0.06 - 0.51), using high protection level masks (OR = 0.05, 95%CI = 0.01 - 0.35), much easier to get infected in respiratory disease than others based on experience (OR = 3.69, 95%CI = 1.58 - 8.63) were all correlated to influenza A (H1N1) infection.</p><p><b>CONCLUSIONS</b>Factors such as history of influenza A (H1N1) vaccine immunization, using high protection level masks and improving respiratory health can protect healthcare workers from infection of influenza A (H1N1).</p>

The significance of different sample types in study of pandemic A (H1N1) influenza diagnosis / 中华预防医学杂志

<p><b>OBJECTIVE</b>To explore the value of different types of samples, including throat swabs, stools, bloods in pandemic A (H1N1) influenza diagnosis and virus shedding patterns.</p><p><b>METHODS</b>From May to June in 2009, 135 samples were collected from 23 confirmed cases of pandemic influenza A (H1N1) infection, including 99 throat swabs, 14 stools, 11 bloods, 1 respiratory tract washing from 13 confirmed cases and 10 blood samples from other confirmed cases. The virus was detected by real-time RT-PCR, the antibody was detected by haemagglutination inhibition assay.</p><p><b>RESULTS</b>For 99 throat swabs of 13 patients, the median time of the first positive real-time RT-PCR was 1 day (ranged from 0 to 7 days) after the onset of the symptoms of illness; the median length of time duration of positive real-time RT-PCR results from throat swabs was 3 days (ranged from 1 to 15 days). Four cases intermittently released virus. One respiratory tract washing sample was positive. In 14 stools, 8 stools were real-time RT-PCR positive, the positive rate was 57.14%. The median time of the positive real-time RT-PCR was 3 days (ranged from 1 to 4 days) after the onset of the symptoms of illness. In 21 blood samples collected at 2 to 9 days of onset, 1 blood sample was real-time RT-PCR positive, the positive rate was 4.76%. All these 21 blood samples were antibody negative.</p><p><b>CONCLUSION</b>Throat swabs and stools samples can be used as A (H1N1) influenza early diagnosis. The length of time duration of positive real-time RT-PCR in throat swabs was longer than stool samples and intermittently releasing of virus were found in throat swabs. Influenza A H1N1 cases showed the presence of small amount of viremia and antibody was negative in early blood samples (< 9 days).</p>

Quantitative evaluation on the effectiveness of prevention and control measures against pandemic influenza A (H1N1) in Beijing, 2009 / 中华流行病学杂志

Objective To quantitatively evaluate the effectiveness of prevention and control measures against pandemic influenza A (H1N1) in Beijing, 2009 and to provide evidence for developing and adjusting strategies for prevention and control of the disease. Methods Considering the seasonality and the number of vaccination on pandemic influenza A (H1N1) , data regarding pandemic influenza A (H1N1) in Beijing were collected and analyzed. Based on the dynamics of infectious disease transmission, a quantitative model for evaluation of prevention and control measures was developed. Results Both latency and infectious periods of pandemic influenza A (H1N1) were estimated to be 1.82 days and 2.08 days, respectively. The effective reproduction numbers of the three periods were 1.13,1.65 and 0.96, respectively. Thanks to the implementation of a series of measures to prevent and control pandemic influenza A (H1N1), the cumulative number of laboratory-confirmed cases of pandemic influenza A (H1N1) was reduced, making it much smaller than what would have been under the natural situation. Specifically, the program on pandemic (H1N1) 2009 vaccination reduced the cumulative number of laboratory-confirmed cases by 24.08% and postponed the peak time. Conclusion Measures that had been taken during this period, had greatly contributed to the successful prevention and control of pandemic influenza A (H1N1). The 2009 Pandemic (H1N1)vaccination was confirmed to have contributed to the decrease of cumulative number of laboratoryconfirmed cases and postponed the peak arrival time.