Xiao-Feng Liang

A Novel Influenza A (H1N1) Vaccine in Various Age Groups

BACKGROUNDnThere is an urgent need for a vaccine that is effective against the 2009 pandemic influenza A (H1N1) virus.nnnMETHODSnA split-virus, inactivated candidate vaccine against the 2009 H1N1 virus was manufactured, and we evaluated its safety and immunogenicity in a randomized clinical trial. Subjects were between 3 and 77 years of age, stratified into four age groups. The immunization schedule consisted of two vaccinations, 21 days apart. Subjects were injected with placebo or with vaccine, with or without alum adjuvant, at doses of 7.5 microg, 15 microg, or 30 microg. Serologic analysis was performed at baseline and on days 21 and 35.nnnRESULTSnA total of 2200 subjects received one dose, and 2103 (95.6%) received the second dose, of vaccine or placebo. No severe adverse side effects associated with the vaccine were noted. In the nonadjuvanted-vaccine groups, injection-site or systemic reactions, most mild in nature, were noted in 5.5 to 15.9% of subjects. Among the subjects receiving 15 microg of nonadjuvanted vaccine, a hemagglutination-inhibition titer of 1:40 or more was achieved by day 21 in 74.5% of subjects between 3 and 11 years of age, 97.1% of subjects between 12 and 17 years, 97.1% of subjects between 18 and 60 years, and 79.1% of subjects 61 years of age or older; by day 35, the titer had been achieved in 98.1%, 100%, 97.1%, and 93.3% of subjects, respectively. The proportion with a titer of 1:40 or more was generally highest among the subjects receiving 30 microg of vaccine, with or without adjuvant. Vaccine without adjuvant was associated with fewer local reactions and greater immune responses than was vaccine with adjuvant.nnnCONCLUSIONSnThese data suggest that a single dose of 15 microg of hemagglutinin antigen without alum adjuvant induces a typically protective immune response in the majority of subjects between 12 and 60 years of age. Lesser immune responses were seen after a single dose of vaccine in younger and older subjects. (ClinicalTrials.gov number, NCT00975572).

Safety and immunogenicity of 2009 pandemic influenza A H1N1 vaccines in China: a multicentre, double-blind, randomised, placebo-controlled trial

BACKGROUNDnThe current influenza pandemic calls for a safe and effective vaccine. We assessed the safety and immunogenicity of eight formulations of 2009 pandemic influenza A H1N1 vaccine produced by ten Chinese manufacturers.nnnMETHODSnIn this multicentre, double-blind, randomised trial, 12 691 people aged 3 years or older were recruited in ten centres in China. In each centre, participants were stratified by age and randomly assigned by a random number table to receive one of several vaccine formulations or placebo. The study assessed eight formulations: split-virion formulation containing 7.5 microg, 15 microg, or 30 microg haemagglutinin per dose, with or without aluminium hydroxide adjuvant, and whole-virion formulation containing 5 microg or 10 microg haemagglutinin per dose, with adjuvant. All formulations were produced from the reassortant strain X-179A (A/California/07/2009-A/PR/8/34). We analysed the safety (adverse events), immunogenicity (geometric mean titre [GMT] of haemagglutination inhibition antibody), and seroprotection (GMT >or=1:40) of the formulations. Analysis was by per protocol. Two sites registered their trial with ClinicalTrials.gov, numbers NCT00956111 and NCT00975572. The other eight studies were registered with the State Food and Drug Administration of China.nnnFINDINGSn12 691 participants received the first dose on day 0, and 12 348 participants received the second dose on day 21. The seroprotection rate 21 days after the first dose of vaccine ranged from 69.5% (95% CI 65.9-72.8) for the 7.5 microg adjuvant split-virion formulation to 92.8% (91.9-93.6) for the 30 microg non-adjuvant split-virion formulation. The seroprotection rate was 86.5% (796 of 920; 84.1-88.7) in recipients of one dose of the 7.5 microg non-adjuvant split-virion vaccine compared with 9.8% (140 of 1432; 8.3-11.4) in recipients of placebo (p<0.0001). One dose of the 7.5 microg non-adjuvant split-virion vaccine induced seroprotection in 178 of 232 children (aged 3 years to <12 years; 76.7%, 70.7-82.0), 211 of 218 adolescents (12 years to <18 years; 96.8%, 93.5-98.7), 289 of 323 adults (18-60 years; 89.5%, 85.6-92.6), and 118 of 147 adults older than 60 years (80.3%, 72.9-86.4), meeting the European Unions licensure criteria for seroprotection in all age-groups. In children, a second dose of the 7.5 microg formulation increased the seroprotection rate to 97.7% (215 of 220, 94.8-99.3). Adverse reactions were mostly mild or moderate, and self-limited. Severe adverse effects occurred in 69 (0.6%, 0.5-0.8) recipients of vaccine compared with one recipient (0.1%, 0-0.2) of placebo. The most common severe adverse reaction was fever, which occurred in 25 (0.22%; 0.14-0.33) recipients of vaccine after the first dose and four (0.04%; 0.01-0.09) recipients of vaccine after the second dose compared with no recipients of placebo after either dose.nnnINTERPRETATIONnOne dose of non-adjuvant split-virion vaccine containing 7.5 microg haemagglutinin could be promoted as the formulation of choice against 2009 pandemic influenza A H1N1 for people aged 12 years or older. In children (aged <12 years), two 7.5 mug doses might be needed.nnnFUNDINGnSinovac Biotech, Hualan Biological Bacterin, China National Biotec Group, Beijing Tiantan Biological Products, Changchun Institute of Biological Products, Changchun Changsheng Life Sciences, Jiangsu Yanshen Biological Technology Stock, Zhejiang Tianyuan Bio-Pharmaceutical, Lanzhou Institute of Biological Products, Shanghai Institute of Biological Products, and Dalian Aleph Biomedical.

Safety of Influenza A (H1N1) Vaccine in Postmarketing Surveillance in China

BACKGROUNDnOn September 21, 2009, China began administering vaccines, obtained from 10 different manufacturers, against 2009 pandemic influenza A (H1N1) virus infection in priority populations. We aimed to assess the safety of this vaccination program.nnnMETHODSnWe designed a plan for passive surveillance for adverse events after immunization with the influenza A (H1N1) vaccine. Physicians or vaccination providers were required to report the numbers of vaccinees and all adverse events to their local Center for Disease Control and Prevention (CDC), which then reported the data to the Chinese CDC through the online National Immunization Information Systems National Adverse Event Following Immunization Surveillance System. Data were collected through March 21, 2010, and were verified and analyzed by the Chinese CDC.nnnRESULTSnA total of 89.6 million doses of vaccine were administered from September 21, 2009, through March 21, 2010, and 8067 vaccinees reported having an adverse event, for a rate of 90.0 per 1 million doses. The age-specific rates of adverse events ranged from 31.4 per 1 million doses among persons 60 years of age or older to 130.6 per 1 million doses among persons 9 years of age or younger, and the manufacturer-specific rates ranged from 4.6 to 185.4 per 1 million doses. A total of 6552 of the 8067 adverse events (81.2%; rate, 73.1 per 1 million doses) were verified as vaccine reactions; 1083 of the 8067 (13.4%; rate, 12.1 per 1 million doses) were rare and more serious (vs. common, minor events), most of which (1050) were allergic reactions. Eleven cases of the Guillain-Barré syndrome were reported, for a rate of 0.1 per 1 million doses, which is lower than the background rate in China.nnnCONCLUSIONSnNo pattern of adverse events that would be of concern was observed after the administration of influenza A (H1N1) vaccine, nor was there evidence of an increased risk of the Guillain-Barré syndrome.

Identification of a new Neisseria meningitidis serogroup C clone from Anhui province, China

BACKGROUNDnOutbreaks of a new serogroup C meningococcal disease emerged during 2003-04 (five outbreaks with 43 cases) and in 2004-05 (five outbreaks with 29 cases), all in Anhui province, China. We describe the molecular epidemiology and features of the causative bacterial strains.nnnMETHODSnWe used pulsed-field gel electrophoresis (PFGE) and multi-locus sequence typing (MLST) to analyse the strains.nnnFINDINGSnOf 34 strains of Neisseria meningitidis cultured during 2003-04 from Anhui province, 31 were group C meningococci, 28 of which were associated with three of five outbreaks; one from a patient and 27 from close contacts of eight patients. Of 30 strains isolated from Anhui province during 2004-05, 17 were identified as serogroup C meningococci, ten of which were associated with four of five outbreaks. In a nationwide survey, 542 strains were isolated during 2004-05; 58 were serogroup C meningococci interspersed among 11 other provinces where no serogroup C outbreak occurred. Of the 106 serogroup C strains analysed, 89 had identical PFGE patterns, designated AH1. Of 28 strains selected for MLST analyses, 25 were sequence type 4821 (ST-4821), which did not belong to any of the previously reported sequence types that can form a new hypervirulent lineage.nnnINTERPRETATIONnST-4821 seems to be unique and caused the serogroup C meningitis outbreaks during the two seasons from 2003 to 2005 in Anhui province. The emergence of this sequence type has epidemiological importance that should be monitored for future spread in China and the rest of the world.

Japanese encephalitis outbreak, Yuncheng, China, 2006.

To the Editor: Japanese encephalitis (JE) epidemics have occurred only in Asia. More than 50,000 cases of JE with ≈10,000 deaths have been reported since 1998 (1,2). The People’s Republic of China reported 5,104 cases and 214 deaths in 2005. Most of these deaths occurred in infants (3,4). n nDuring July and August 2006, an outbreak of viral encephalitis occurred in Yuncheng, Shanxi Province, People’s Republic of China. A total of 66 cases (1.32/100,000 population) were reported, including 19 deaths (case-fatality rate 28.8%). The cases had a widespread distribution over 9 counties and involved 37 towns and 61 administrative villages. The ratio of male-to-female patients was 1:0.89. A distinct clinical feature of this outbreak was the age distribution. More than 86% of the patients were >30 years of age, with only 10% of patients 50 years of age (5). n nWe report serologic and virologic findings for the 2006 outbreak of viral encephalitis. Forty-six clinical specimens collected from 34 patients who had a diagnosis of viral encephalitis, including 33 serum samples and 13 cerebrospinal fluid (CSF) samples, were studied. All serum samples were screened for immunoglobulin M (IgM) to West Nile virus (WNV) by using the WNV IgM-capture ELISA kit (PanBio, Brisbane, Queensland, Australia) and for IgM to dengue virus or Japanese encephalitis virus (JEV) by using the JE-Dengue IgM Combination ELISA kit (PanBio). Results for JEV were confirmed by using the JE Virus IgM-Capture ELISA kit (Shanghai B & C Enterprise Development Co. Ltd, Shanghai, People’s Republic of China). n nWNV-specific or dengue virus–specific IgM was not detected in any samples. JEV-specific IgM was detected in 27 (80%) patients, which indicated recent JEV infections. The other 7 patients were negative for JEV by ELISA and reverse transcription–PCR (RT-PCR). Increases >4-fold in neutralizing antibodies were detected in acute- and convalescent-phase serum samples from 9 patients (10 serum pairs were collected during the outbreak). n nAttempts were made to detect virus in CSF of patients and in 2,400 mosquitoes. Mosquitoes (mainly Culex spp.) were collected in cow sheds and hog pens around houses and processed into pools of 100. Total RNA was extracted from CSF or mosquito homogenate by using the QIAamp viral RNA extraction kit (QIAGEN, Valencia, CA, USA) according to the manufacturer’s specifications. RT was performed by using Ready-To-Go-You Prime First Strand Beads (Amersham Pharmacia Biotech, Piscatawy, NJ, USA) and a seminested PCR to amplify 492-bp gene fragments of the premembrane (PrM) sequence of JEV by using the Takara LA Taq PCR kit (Takara Bio Inc., Shiga, Japan). The primers were derived from Ishikawa strain genome sequences (GenBank accession no. {type:entrez-nucleotide,attrs:{text:AB051292,term_id:12082323,term_text:AB051292}}AB051292). Primers PrMF: 5′-CGT TCT TCA AGT TTA CAG CAT TAG C-3′ (251–275), PrMR1: 5′-CGY TTG GAA TGY CTR GTC CG-3′ (724–743), and PrMR2: 5′-CCY RTG TTY CTG CCA AGC ATC CAM CC-3′ (901–925) were used. n nJEV PrM gene was amplified from CSF of 6 (46%) of 13 patients and 10 of 24 pools of mosquitoes by using the same seminested RT-PCR. To identify JEV genotype(s) involved in this outbreak, PCR products were sequenced. Eleven sequences (GenBank accession nos. {type:entrez-nucleotide-range,attrs:{text:EF434264-EF434274,start_term:EF434264,end_term:EF434274,start_term_id:148925198,end_term_id:148925218}}EF434264-EF434274) were obtained from 6 patients and 5 pools of mosquitoes. The 11 sequences were compared phylogenetically with17 known JEV strains of the 4 recognized genotypes (classified on the basis of a 240-nt region of the prM gene). As shown in the Figure, the 11 sequences were those of JEV. n n n nFigure n nPhylogenetic analysis of Japanese encephalitis virus strains predicted from premembrane gene sequences. Neighbor-joining tree was generated by using MEGA 3.1 software (www.megasoftware.net) and rooted with Murray Valley encephalitis (MVE) virus sequence ... n n n nFurther analysis showed that these 11 sequences can be grouped into genotypes I and III. Both genotypes were found in patient and mosquito samples, indicating that these genotypes co-circulated during this JE outbreak. n nJE has been endemic in Yuncheng for many years (6). A vaccine against JE (SA14–14–2) has been used in this area in infants, but not in adults. This might be 1 reason why a higher adult incidence was found in this outbreak. JEV genotype III had been the predominant genotype in previous years, but genotype I has been recently detected at increased frequencies (7–10). Detection of 2 JEV genotypes in 1 epidemic has not been reported. Whether simultaneous circulation of >1 genotype during an outbreak indicates a new type of emergence of JEV or that this has occurred and not been detected is unknown.

Japanese Encephalitis, Tibet, China

To the Editor: Tibet is located in the Qinghai-Tibet Plateau of western People’s Republic of China and has been internationally recognized as a Japanese encephalitis (JE)–nonendemic area because the average altitude is thought to be too high to facilitate the cycle of Japanese encephalitis virus (JEV) between mosquitoes and vertebrates (1,2). In addition, JE is a reportable infectious disease in China, and no clinically confirmed case has been reported in Tibet since establishment of a national case reporting system in 1951 (3,4). Neither the mosquito vector of JEV nor JEV isolates have been described in Tibet. In this study, JEV was isolated from Culex tritaeniorhynchus mosquitoes, the main vectors of JEV, collected in Tibet. Serologic assays detected anti-JEV antibodies in a large number of human and porcine serum samples collected in this region. These data demonstrate that JEV is currently circulating in Tibet. n nDuring August 5–15, 2009, mosquitoes were collected in Mainling County (altitude 2,900 m) and Medog County (altitude 1,000 m) in the Nyingchi area of Tibet. A total of 4,089 mosquitoes representing 7 species (Cx. tritaeniorhynchus, Cx. pipiens pallens, Cx. bitaeniorhynchus, Armigeres obturbans, Anopheles maculatus maculates, An. peditaeniatu, and Aedes albopictus) from 4 genera were collected in this study. The dominant mosquito species detected in Medog County was Cx. tritaeniorhynchus (2,442 [71.1%] of 3,436 mosquitoes collected there) (Table); no previous reports have described this species in Tibet. A total of 653 mosquitoes were collected in Mainling County, of which 489 (74.9%) were Armigeres obturban. No Cx. tritaeniorhynchus mosquitoes were collected in Mainling County. n n n nTable n nResults from testing of mosquitoes, humans, and pigs for JEV, Nyingchi area, Tibet, People’s Republic of China, 2009* n n n nMosquitoes were homogenized in 97 pools by using TissueLyser (QIAGEN, Hilden, Germany) and screened with reverse transcription–PCR (RT-PCR) by using seminested primers designed to detect the JEV PreM gene (5). One Cx. tritaeniorhynchus pool, XZ0938, collected in Medog County was positive by PCR. Isolation of virus was conducted from PCR-positive sample by injecting mosquito homogenate supernatants into monolayers of BHK-21 and C6/36 cells. The supernatant of pool XZ0938 caused cytopathic effects in BHK-21 and C6/36 cells in successive cell passages. The complete genome of 10,965 nt was sequenced (GenBank accession no. {type:entrez-nucleotide,attrs:{text:HQ652538,term_id:337263366,term_text:HQ652538}}HQ652538) as described (6), which included a 96-nt 5′ nontranslated region and a 570-nt 3′ nontranslated region. The single open reading frame coded for a polyprotein of 3,432 aa. Compared with the complete genome sequences of 62 known JEV isolates, the nucleotide sequence identity varied from 83.6% to 97.8% and amino acid sequence identity from 94.9% to 99.7%. Phylogenetic trees derived from nucleotide sequences of the complete genome of JEV strains indicated that XZ0938 was a member of genotype I JEV. A more detailed analysis indicated that the Tibet JEV is most closely related to JEV isolates KV1899 (1999, Korea, {type:entrez-nucleotide,attrs:{text:AY316157,term_id:32187331,term_text:AY316157}}AY316157), and JEV/sw/Mie/41/2002 (2002, Japan, {type:entrez-nucleotide,attrs:{text:AB241119,term_id:81687252,term_text:AB241119}}AB241119) (data not shown). n nTo determine whether local residents were infected by JEV, 248 human serum samples were collected in Mainling and Medog Counties from healthy persons. Neutralizing antibody against JEV was tested by 90% plaque-reduction neutralization tests by using standard methods (7). Serum samples were tested with serial 2-fold dilutions from 1 to 5. Diluted serum was mixed with equal volumes of culture medium containing JEV P3 strain. The samples were considered positive when the neutralizing antibody titers >10. Sixty-eight positive samples were determined by 90% plaque-reduction neutralization tests, which constituted 68 (27.4%) of all 248 serum samples. Twenty-two (22.0%) of 100 and 46 (31.1%) of 148 serum samples in Mainling and Medog Counties, respectively, were positive (Table). Currently, the local population is not vaccinated against JEV (8) because Tibet is considered a JE-nonendemic area (1–4). The observation that 68 (27.4%) of 248 serum samples from healthy humans contained neutralizing antibody against JEV at titers >10 suggests that this population is subject to substantial levels of subclinical JEV infection. n nTo determine the present situation of JEV infection in local pigs, we analyzed 66 serum samples collected from piglets 1–6 months of age in Mainling and Medog Counties; immunoglobulin M antibodies against JEV were detected by capture ELISA as described (9). That 22 (33.3%) of 66 piglet serum samples were positive for immunoglobulin M against JEV suggested that local pigs have been newly infected by JEV in 2009 and have participated in the cycles of JEV in the local area (Table). n nJE is a global public health issue that has spread to >20 countries in Asia (6,10). In this study, we present evidence that JEV has extended its geographic range to Tibet, a region that previously was believed to be free of JE because of its elevation. Factors such as global warming, increased pig farming, and increased tourism and transportation may have contributed to the emergence of JE in Tibet. Conditions in Tibet, including the presence of the primary vector (Cx. tritaeniorhynchus mosquitoes), abundant amplification hosts (pig), and a naive population that has not been vaccinated against JEV, present the possibility for JE outbreaks. Increased surveillance for JE in this region is needed.

Prevention of Chronic Hepatitis B after 3 Decades of Escalating Vaccination Policy, China

China’s hepatitis B virus (HBV) prevention policy has been evaluated through nationally representative serologic surveys conducted in 1992 and 2006. We report results of a 2014 serologic survey and reanalysis of the 1992 and 2006 surveys in the context of program policy. The 2014 survey used a 2-stage sample strategy in which townships were selected from 160 longstanding, nationally representative, county-level disease surveillance points, and persons 1–29 years of age were invited to participate. The 2014 sample size was 31,713; the response rate was 83.3%. Compared with the 1992 pre–recombinant vaccine survey, HBV surface antigen prevalence declined 46% by 2006 and by 52% by 2014. Among children <5 years of age, the decline was 97%. China’s HBV prevention program, targeted toward interrupting perinatal transmission, has been highly successful and increasingly effective. However, this progress must be sustained for decades to come, and elimination of HBV transmission will require augmented strategies.

Distribution of serogroups and sequence types in disease-associated and carrier strains of Neisseria meningitidis isolated in China between 2003 and 2008

Given the unpredictability of Neisseria meningitidis outbreaks and the increased prevalence of serogroup C strains following the introduction of serogroup A-based vaccines, we conducted an analysis of serogroups and sequence types (STs) in disease-associated and carrier N. meningitidis isolates that have emerged in China since 2003. We used multilocus sequence-typing techniques to investigate 371 N. meningitidis strains isolated from patients with meningitis and healthy carriers. Two lineages were identified in serogroup A and C isolates, genotyped as the ST5 complex and ST4821 complex, respectively. Both clonal complexes were found throughout China, although ST4821 was more concentrated in the eastern region of the country. The ST5 complex has been persistent in China since the late 1980s and has since spread across the entire country. Isolates belonging to the ST4821 complex have been a dominant lineage since 2003.

Population-based Surveillance for Bacterial Meningitis in China, September 2006–December 2009

Greater use of appropriate specimen collection and confirmatory laboratory testing is needed.

Genotypic characterization of Neisseria meningitidis serogroup B strains circulating in China

OBJECTIVEnIn China, comparatively little research has been directed at serogroup B meningococci, which are mainly isolated from healthy individuals. We attempted to study the genotypic characterization of Neisseria meningitidis serogroup B strains.nnnMETHODSnWe analyzed 150 N. meningitidis strains isolated in China during 1975-2005 by multilocus sequence typing (MLST) and porA typing.nnnRESULTSnA total of 88 different sequence types (STs) were identified by MLST, 73 of which were newly identified. Seven complexes previously identified in other countries and three unique clonal lineages first identified in China were detected, seven of which had previously been described as hyperinvasive meningococcal lineages. Several lineages were found in specified period. A total of 63 different porA types were found, 11 of which were novel. The most common porA types were P1.5-1,2-2 (17 isolates), P1.5-1,10-4 (12 isolates), P1.5-2,2-2 (eight isolates) and P1.7-2,4 (seven isolates).nnnCONCLUSIONnIn this context, serogroup B meningococci provide a diverse, continually reassorted gene pool from which new genotypes arise. The most important mechanism is probably horizontal genetic exchange among N. meningitidis serogroup B strains, possibly resulting in the emergence of new meningococcal clones. These results may help our understanding of the genotypic distribution of serogroup B meningococci and provide clues for further study of this organism.