An Observational Prospective Cohort Study of Vaccine Effectiveness Against Severe Acute Respiratory Syndrome Coronavirus 2 Infection of an Aerosolized, Inhaled Adenovirus Type 5-Vectored Coronavirus Disease 2019 Vaccine Given as a Second Booster Dose in Guangzhou City, China.

Using a prospective, observational cohort study during the post-"dynamic COVID-zero" wave in China, we estimated short-term relative effectiveness against Omicron BA.5 infection of inhaled aerosolized adenovirus type 5-vectored ancestral strain coronavirus disease 2019 (COVID-19) vaccine as a second booster dose approximately 1 year after homologous boosted primary series of inactivated COVID-19 vaccine compared with no second booster. Participants reported nucleic acid or antigen test results weekly until they tested positive or completed predesignated follow-up. After excluding participants infected <14 days after study entry, relative effectiveness among the 6576 participants was 61% in 18- to 59-year-olds and 38% in ≥60-year-olds and was sustained for 12 weeks.

Safety, immunogenicity and protection of heterologous boost with an aerosolised Ad5-nCoV after two-dose inactivated COVID-19 vaccines in adults: a multicentre, open-label phase 3 trial.

BACKGROUND: Aerosolised Ad5-nCoV is one of the first licensed mucosal respiratory vaccine against SARS-CoV-2 in the world; however, the safety profile of this vaccine has not been reported in a large population yet. METHODS: This multicentre, open-label phase 3 trial, done in 15 centres in six provinces (Jiangsu, Hunan, Anhui, Chongqing, Yunnan, Shandong) in China, aimed to evaluate the safety and immunogenicity of aerosolised Ad5-nCoV in healthy adults (members of the general population with no acute febrile disorders, infectious disease, serious cardiovascular diseases, serious chronic diseases or progressive diseases that cannot be controlled) at least 18 years old, who had received two doses of inactivated COVID-19 vaccine as their primary regimen. This study contained a non-randomly assigned safety cohort and a centrally randomly assigned (1:1) immunogenicity subcohort. The patients in the immunogenicity subcohort received aerosolised Ad5-nCov (aerosolised Ad5-nCoV group) or inactivated vaccine (inactivated COVID-19 group) The primary endpoints were the incidence of adverse reactions within 28 days following the booster vaccination with aerosolised Ad5-nCoV in the safety population (collected through a daily record of any solicited or unsolicited adverse events filled by each participant) and the geometric mean titre of neutralising antibodies at day 28 after the booster dose in the immunogenicity subcohort (measured with a pseudovirus neutralisation test). This study was registered with ClinicalTrials.gov, NCT05204589. FINDINGS: Between Jan 22, 2022, and March 12, 2022, we recruited 11 410 participants who were screened for eligibility, of whom 10 267 (99·8%) participants (5738 [55·9%] men, 4529 [44·1%] women; median age 53 years [18-92]) received the study drugs: 9847 (95·9%) participants in the open-label cohort to receive aerosolised Ad5-nCoV, and 420 (4·1%) in the immunogenicity subcohort (212 in the aerosolised Ad5-nCoV group and 208 in the inactivated vaccine group). Adverse reactions were reported by 1299 (13%) of 10 059 participants within 28 days after receiving the booster vaccination with aerosolised Ad5-nCoV, but most of the adverse reactions reported were mild to moderate in severity. Participants in the aerosolised Ad5-nCoV group had a significantly higher level of the neutralising antibodies against omicron BA.4/5 (GMT 107·7 [95% CI 88·8-130·7]) than did those in the inactivated vaccine group (17·2 [16·3-18·2]) at day 28. INTERPRETATION: The heterologous booster regimen with aerosolised Ad5-nCoV is safe and highly immunogenic, boosting both systemic and mucosal immunity against omicron subvariants. FUNDING: National Natural Science Foundation of China, Jiangsu Provincial Science Fund for Distinguished Young Scholars, and Jiangsu Provincial Key Project of Science and Technology Plan. TRANSLATION: For the Chinese translation of the abstract see Supplementary Materials section.

Real-World Effectiveness of Primary Series and Booster Doses of Inactivated Coronavirus Disease 2019 Vaccine Against Omicron BA.2 Variant Infection in China: A Retrospective Cohort Study.

BACKGROUND: China has been using inactivated coronavirus disease 2019 (COVID-19) vaccines as primary series and booster doses to protect the population from severe to fatal COVID-19. We evaluated primary and booster vaccine effectiveness (VE) against Omicron BA.2 infection outcomes. METHODS: This was a 13-province retrospective cohort study of quarantined close contacts of BA.2-infected individuals. Outcomes were BA.2 infection, COVID-19 pneumonia or worse, and severe/critical COVID-19. Absolute VE was estimated by comparison with an unvaccinated group. RESULTS: There were 289 427 close contacts ≥3 years old exposed to Omicron BA.2 cases; 31 831 turned nucleic acid amplification test-positive during quarantine, 97.2% with mild or asymptomatic infection, 2.6% with COVID-19 pneumonia, and 0.15% with severe/critical COVID-19. None died. Adjusted VE (aVE) against any infection was 17% for primary series and 22% when boosted. Primary series aVE in adults >18 years was 66% against COVID-19 pneumonia or worse and 91% against severe/critical COVID-19. Booster dose aVE was 74% against pneumonia or worse, and 93% against severe/critical COVID-19. CONCLUSIONS: Inactivated COVID-19 vaccines provided modest protection from infection, very good protection against pneumonia, and excellent protection against severe/critical COVID-19. Booster doses are necessary to provide strongest protection.

Detection of a Highly Divergent Type 3 Vaccine-Derived Poliovirus in a Child with a Severe Primary Immunodeficiency Disorder - Chongqing, China, 2022.

Oral poliovirus vaccine (OPV) has proven to be highly effective in the global effort to eradicate poliomyelitis because of its ability to induce both humoral and intestinal immunity, ease of administration, and low cost (1). Sabin-strain OPV contains live attenuated virus and induces immunity by replicating in the intestinal tract, triggering an immune response that clears the vaccine virus. However, among undervaccinated communities and persons with immunodeficiency, OPV mutations that arise during prolonged replication can result in the emergence of genetically divergent, neurovirulent vaccine-derived polioviruses (VDPVs). In addition, OPV has resulted in rare cases of vaccine-associated paralytic poliomyelitis (VAPP) among vaccine recipients or their close contacts (1). Identification of circulating polioviruses relies on surveillance of acute flaccid paralysis (AFP) and environmental surveillance of wastewater (i.e., sewage). In 2022, type 3 VDPV (VDPV3) was detected in stool specimens from an infant with primary immunodeficiency disorder (PID) through a pilot surveillance program to identify VDPVs in children with PIDs. Integrated AFP, environmental, and immunodeficiency-associated VDPV (iVDPV) surveillance is critical to detecting and containing all polioviruses and achieving the goal of global polio eradication.

A case-case study on the effect of primary and booster immunization with China-produced COVID-19 vaccines on prevention of pneumonia and viral load among vaccinated persons infected by Delta and Omicron variants.

Using a three-prefecture, two-variant COVID-19 outbreak in Henan province in January 2022, we evaluated the associations of primary and booster immunization with China-produced COVID-19 vaccines and COVID-19 pneumonia and SARS-CoV-2 viral load among persons infected by Delta or Omicron variant. We obtained demographic, clinical, vaccination, and multiple Ct values of infections ≥3 years of age. Vaccination status was either primary series ≥180 days prior to infection; primary series <180 days prior to infection, or booster dose recipient. We used logistic regression to determine odds ratios (OR) of Delta and Omicron COVID-19 pneumonia by vaccination status. We analysed minimum Ct values by vaccination status, age, and variant. Of 826 eligible cases, 405 were Delta and 421 were Omicron cases; 48.9% of Delta and 19.0% of Omicron cases had COVID-19 pneumonia. Compared with full primary vaccination ≥180 days before infection, the aOR of pneumonia was 0.48 among those completing primary vaccination <180 days and 0.18 among booster recipients among these Delta infections. Among Omicron infections, the corresponding aOR was 0.34 among those completing primary vaccination <180 days. There were too few (ten) Omicron cases among booster dose recipients to calculate a reliable OR. There were no differences in minimum Ct values by vaccination status among the 356 Delta cases or 70 Omicron cases. COVID-19 pneumonia was less common among Omicron cases than Delta cases. Full primary vaccination reduced pneumonia effectively for 6 months; boosting six months after primary vaccination resulted in further reduction. We recommend accelerating the pace of booster dose administration.

Changes in the epidemiology of hepatitis A in three socio-economic regions of China, 1990-2017.

BACKGROUND: Hepatitis A (HepA) vaccination and economic transitions can change the epidemiology of HepA. China's Gross Domestic Product (GDP) per capita was known to be inversely associated with the incidence of HepA, but a deeper understanding of the epidemiology of HepA in different socio-economic regions is lacking. We compare the changing epidemiology of HepA in three socioeconomic-geographic regions of China. METHODS: We obtained data on all HepA cases reported through the National Notifiable Disease Reporting System and assessed trends and changes in age-specific incidence rates by age quartile and season. We categorized the country into three regions, the sequential years into five era, compared the incidence, quartile age, seasonal intensity and coverage of HepA of the three regions. Linear regression was performed to analyse trends in incidence of HepA and to analyse the association between coverage and incidence. RESULTS: The annual mean incidences of HepA in the eastern, central, and western regions decreased from 63.52/100 000, 50.57/100 000 and 46.39/100 000 in 1990-1992 to 1.18/100 000, 1.05/100 000 and 3.14/100 000 in 2012-2017, respectively. Decreases in incidence were seen in all age groups in the three regions; the incidence was highest (9.3/100 000) in the youngest age group (0-4 years) of the western region, while in the central region, the age group with the highest incidence changed from 0 to 9 years to adults ≥60 years old. In 2017, the median age of HepA cases was 43 years (Q1-Q3: 33-55), 47 years (Q1-Q3: 32-60) and 33 years (Q1-Q3: 9-52) in the eastern, central, and western provinces, respectively. Seasonal peaks became smaller or were nearly elimination nationwide, but seasonality persisted in some provinces. After the Expanded Program on Immunization (EPI) included HepA vaccine into the routine schedule in 2007, HepA coverage increased to > 80% in the three regions and was negatively association with the HepA incidence. CONCLUSION: The incidence of HepA decreased markedly between 1990 and 2017. A socioeconomic inequity in coverage of HepA vaccine was almost eliminated after HepA vaccine was introduced into China's EPI system, but inequity in incidence still existed in lower socio-economic developed region.

Compliance among infants exposed to hepatitis B virus in a post-vaccination serological testing program in four provinces in China.

BACKGROUND: Mother to child transmission of hepatitis B virus (HBV) remains the most common form of HBV infection in China. Prevention of HBV vertical transmission involves timely administration of the complete hepatitis B vaccine (HepB) series and hepatitis B immunoglobulin. Post-vaccination serological testing (PVST) is utilized to determine an infant's outcome after HBV exposure and completion of HepB series. We aim to determine the frequency of compliance with a PVST testing cascade for HBV infected mothers and analyze factors associated with infant lost to follow up (LTFU). METHODS: We conducted a retrospective cohort review of previously collected data in Fujian, Jiangxi, Zhejiang and Chongqing provinces in China from 1 June 2016-31 December 2017. The study population included all HBV-exposed infants and their mothers. SAS software was used for statistical analyses. Bivariate and multivariate regression analyses (presented in odds ratio [OR] with 95% confidence intervals [CI]) were used to compare the proportional differences of factors associated with PVST not being completed. RESULTS: Among enrolled 8474 target infants, 40% of them transferred out of the study provinces without further information and 4988 were eligible for PVST. We found 20% (994) of infants were not compliant with the testing cascade: 55% of LTFU occurred because parents refused venous blood sample collection or failure of sample collection in the field, 16% transferred out after 6 months of age, and 10% of families chose to have independent, confidential PVST completed without reporting results. High PVST noncompliance rates were more likely to be from Fujian (aOR = 17.0, 95% CI: 9.7-29.9), Zhejiang (aOR = 5.7, 95% CI: 3.2-10.1) and Jiangxi (aOR = 1.9, 95% CI: 1.0-3.4), and from HBV e antigen positive mother (aOR = 1.2, 95% CI: 1.1-1.4). CONCLUSIONS: This study found that the LTFU rate reached 20% in PVST program, which was a significant problem. We recommend implementing a national electronic information system for tracking HBV at risk mother-infant pairs; encourage further research in developing a less invasive means of completing PVST, and take effective measures nationally to reduce HBV stigma. Without reducing the loss to follow up rate among infants eligible for PVST, elimination of vertical HBV transmission will be impossible.

The Public Health Burden of Rotavirus Disease in Children Younger Than Five Years and Considerations for Rotavirus Vaccine Introduction in China.

BACKGROUND: Rotavirus is the leading cause of severe diarrhea among young children worldwide. Rotavirus vaccines have demonstrated substantial benefits in many countries that have introduced vaccine nationally. In China, where rotavirus vaccines are not available through the national immunization program, it will be important to review relevant local and global information to determine the potential value of national introduction. Therefore, we reviewed evidence of rotavirus disease burden among Chinese children younger than 5 years to help inform rotavirus vaccine introduction decisions. METHODS: We reviewed scientific literature on rotavirus disease burden in China from 1994 through 2014 in China National Knowledge Infrastructure, Wanfang and PubMed. Studies were selected if they were conducted for periods of 12 month increments, had more than 100 patients enrolled and used an accepted diagnostic test. RESULTS: Overall, 45 reports were included and indicate that rotavirus causes ~40% and ~30% of diarrhea-related hospitalizations and outpatient visits, respectively, among children younger than 5 years in China. Over 50% of rotavirus-related hospitalizations occur by age 1 year; ~90% occur by age 2 years. Regarding circulating rotavirus strains in China, there has been natural, temporal variation, but the predominant local strains are the same as those that are globally dominant. CONCLUSIONS: These findings affirm that rotavirus is a major cause of childhood diarrheal disease in China and suggest that a vaccination program with doses given early in infancy has the potential to prevent the majority of the burden of severe rotavirus disease.

A practical community-based response strategy to interrupt Ebola transmission in sierra Leone, 2014-2015.

BACKGROUND: The Ebola virus disease spread rapidly in West Africa in 2014, leading to the loss of thousands of lives. Community engagement was one of the key strategies to interrupt Ebola transmission, and practical community level measures needed to be explored in the field and tailored to the specific context of communities. METHODS: First, community-level education on Ebola virus disease (EVD) prevention was launched for the community's social mobilizers in six districts in Sierra Leone beginning in November 2014. Then, from January to May of 2015, in three pilot communities, local trained community members were organized to engage in implementation of EVD prevention and transmission interruption measures, by involving them in alert case report, contact tracing, and social mobilization. The epidemiological indicators of transmission interruption in three study communities were evaluated. RESULTS: A total of 6 016 community social mobilizers from 185 wards were trained by holding 279 workshops in the six districts, and EVD message reached an estimated 631 680 residents. In three pilot communities, 72 EVD alert cases were reported, with 70.8 % of them detected by trained local community members, and 14 EVD cases were finally identified. Contact tracing detected 64.3 % of EVD cases. The median duration of community infectivity for the cases was 1 day. The secondary attack rate was 4.2 %, and no third generation of infection was triggered. No health worker was infected, and no unsafe burial and noncompliance to EVD control measures were recorded. The community-based measures were modeled to reduce 77 EVD cases, and the EVD-free goal was achieved four months earlier in study communities than whole country of Sierra Leone. CONCLUSIONS: The community-based strategy of social mobilization and community engagement was effective in case detection and reducing the extent of Ebola transmission in a country with weak health system. The successfully practical experience to reduce the risk of Ebola transmission in the community with poor resources would potentially be helpful for the global community to fight against the EVD and the other diseases in the future.

A Centralized Report on Pediatric Japanese Encephalitis Cases from Beijing Children's Hospital, 2013.

Fifteen pediatric cases of suspected Japanese encephalitis (JE) were reported in Beijing Children's Hospital during the late summer of 2013. The clinical manifestations in most cases included high fever, seizures, and abnormal magnetic resonance imaging findings. Twelve of 15 cases were laboratory-confirmed as JE cases by pathogen identification. Epidemiological investigations showed that five of the 12 laboratory-confirmed patients had an incomplete JE vaccination history. Follow-up investigations after discharge indicated that seven laboratory-confirmed JE patients without JE vaccinations had relatively poor prognoses, with an average Modified Rankin Scale (MRS) score of 2.6 when compared with the other five laboratory-confirmed, JE-vaccinated patients with an average MRS score of 0.5. The observation of pediatric JE cases among those with a history of JE vaccination warrants further attention.

An outbreak of type π vaccine-derived poliovirus in Sichuan province, China: emergence and circulation in an under-immunized population.

BACKGROUND: During August 2011-February 2012, an outbreak of type Π circulating vaccine-derived poliovirus (cVDPVs) occurred in Sichuan Province, China. METHODS: A field investigation of the outbreak was conducted to characterize outbreak isolates and to guide emergency response. Sequence analysis of poliovirus capsid protein VP1 was performed to determine the viral propagation, and a coverage survey was carried out for risk assessment. RESULTS: One clinical compatible polio case and three VDPV cases were determined in Ngawa County, Ngawa Tibetan and Qiang Autonomous Prefecture, Sichuan Province. Case patients were unimmunized children, 0.8-1 years old. Genetic sequencing showed that the isolates diverged from the VP1 region of the type Π Sabin strain by 5-12 nucleotides (nt) and shared the same 5 nt VP1 substitutions, which indicate single lineage of cVDPVs. Of the 7 acute flaccid paralysis cases (all>6 months) reported in Ngawa Prefecture in 2011, 4 (57.1%) cases (including 2 polio cases) did not receive oral attenuated poliovirus vaccine. Supplementary immunization activities (SIAs) were conducted in February-May, 2012, and the strain has not been isolated since. CONCLUSION: High coverage of routine immunization should be maintained among children until WPV transmission is globally eradicated. Risk assessments should be conducted regularly to pinpoint high risk areas or subpopulations, with SIAs developed if necessary.

Epidemiological characteristics of Japanese encephalitis in Guizhou Province, China, 1971-2009.

OBJECTIVE: The aim of the study was to establish the contemporary epidemiological characteristics of Japanese encephalitis (JE) in Guizhou Province. METHODS: A retrospective study of National Notifiable Disease Reporting System (NNDRS) data from 1971 through 2009, was conducted to ascertain the geographical, seasonal, and age distributions of JE incidence in Guizhou Province, China. RESULTS: A total of 68 425 JE cases were reported in Guizhou from 1971-2009. The JE cases occurred sporadically in all 9 prefectures of Guizhou, mostly among residents of rural areas. Seasonal distribution of JE remained consistent over the period from 1971-2009 with the main transmission season starting from June to September and peaking in August. JE occurred mainly in children under the age of 15 years with peak incidence in the 0-6-year age group. Pearson's correlation analysis showed that JE vaccine distribution had a negative correlation with JE incidence rates during 1971-2009 (coefficient of correlation=-0.475, P<0.01). CONCLUSION: Over the period of 1971-2009, the JE incidence rate had declined dramatically in terms of geographical and age distributions due to JE vaccination to children at risk.

[Surveillance of healthy people's Japanese encephalitis neutralizing antibody in some areas of Henan Province].

OBJECTIVE: To analyze the prevalence characteristics and influence factors of Japanese encephalitis (JE) neutralizing antibody in healthy people. METHODS: Xinyang and Luoyang is the two cities in Henan Province. In 2010, healthy people of these two cities were selected by random sampling method to eight age groups: less than one year old, 1 -2 years old, 3 -4, 5 -6, 7 -14, 15 -19, 20 -59,and above 60 years old, their blood specimens were collected in May before JE infection and in November after JE infection, then followed with epidemiological investigation for JE neutralizing antibody by MCPENT. RESULTS: 519 healthy people were surveyed, 1008 effective blood specimens were collected and tested. The JE neutralizing antibody positive rate was 59.52% in men, and 67.39% in male, these two rates had no statistical significance (chi2 = 3.41, P > 0.05). The JE neutralizing antibody was 58.66% in May, and 61.20% in November, these two rates had no statistical significance (chi2 = 0.68, P > 0.05). The JE neutralizing antibody positive rate of 0 - 14 years old age group was 55.19% in Xinyang, and 45.03% in Luoyang,these two rates had no statistical significance (chi2 = 3.53, P > 0. 05). The JE neutralizing antibody positive rate of above 15 years old age group is 97.78% in Xinyang,and 48.94% in Luoyang, these two rates had statistical significance (chi2 = 55.42, P < 0.05). The JE neutralizing antibody positive rate of JE vaccination was 56.85%, and 38.35% in no JE vaccination, these two rates had statistical significance (chi2 = 10.88, P < 0.05). CONCLUSION: The JE neutralizing antibody positive rate was showing significant differences in people above 15 years old between Xinyang and Luoyang. The JE neutralizing antibody positive rate was showing significant differences between JE vaccination and no vaccination. Xinyang and Luoyang City, recommended strengthening the 0 - 14 year-olds immunized, and at the same time, exploring and paying attention to JE immunization strategy of people above 15 years old in Luoyang.

[Analysis on disease burdern of Japanese encephalitis (JE) in Gansu province].

OBJECTIVE: To evaluate the disease burden of Japanese Encephalitis (JE), and provide strategy for disease control and prevention. METHODS: Firstly, analysis the incidence, mortality and fatality rate of JE in Gansu province in 2006. Then the investigation was carried out for calculating all expenditure items of the patients, including medical cost of the hospitalization, medicines, the transport costs, and other non-medical direct cost. RESULTS: In 2006, among the 27 type A and B notifiable infectious diseases in Gansu Province, JE mortality rate was at the top 3, fatality rate was at first rank. The direct cost of JE disease was 6889 RMB per case. In 2006, the direct cost of JE cases was 1,116,000 RMB in Gansu Province. CONCLUSION: JE had the high mortality, and fatality. The fatality in adult was higher than in children. JE patients had to pay high costs. JE disease burden should not be underestimated.

[Meta-analysis on serological effect of the primary vaccination for Japanese encephalitis of the literatures].

OBJECTIVES: To summary and compare the different seroconversion rates after the primary vaccination for the Japanese encephalitis (JE), and to evaluate the serological effect of 3 kinds of JE vaccines. METHOD: Searching "CHKD", "Wanfang" database and "EMCC" databases, the studies of the immunogenicity after the primary JEV vaccination, all randomized controlled trials or non-randomized controlled trials were included, and statistical analysis were made by RevMan 4.2.10 software. RESULTS: A total of 12 literatures were included, 7 studies had control groups. The seroconversion rates after the primary vaccination, JEV-L, JEV-I (Vero) and JEV-I (PHK), were 86% (95% CI: 80%-91%), 83% (95% CI: 72% -94%) and 64% (95% CI: 58%-69%) respectively. Comparing the seroconversion rates of the 3 kinds of vaccines after primary immunization, the rate of JEV-I (Vero) was significantly higher than the rate of JEV-I (PHK), other comparisons were no significant difference. CONCLUSION: The serological effects of JEV-L and JEV-I (Vero) after the primary vaccination were higher than that of JEV-I (PHK).

[Analysis of prevalence season and trend of meningococcal disease by circular distribution in China].

OBJECTIVE: To analyze the prevalence season and trend of meningococcal disease in China by epidemic years from 2004 to 2008 in order to provide scientific basis for making strategies ofmeningococcal disease prevention and control. METHODS: The incidence numbers of meningococcal disease were calculated by weeks, epidemic years and areas. The seasonality and prevalence trends of meningococcal disease were analyzed by circular distribution. RESULTS: The incidence trend of meningococcal disease had obvious seasonality in China (P < 0.01). The peak of meningococcal disease were different by epidemic years and areas (P < 0.01). There were no association between annual incidence rates and seasonality. CONCLUSIONS: We should strength meningococcal disease surveillance before epidemic peak period,and put immunoprophylaxis first and carry out comprehensive measures of prevention and control.

[Analysis on data from the clinical acute viral encephalitis surveillance system in three prefectures in Shaanxi during 2005 - 2006].

OBJECTIVE: To describe the epidemiological features of viral encephalitis and burden of Japanese encephalitis (JE), and to identify potential strategies for effective JE control measures, using data from the Viral Encephalitis Surveillance Program (VESP) launched in Ankang, Baoji, and Weinan prefectures, Shaanxi province. METHODS: Data was gathered from sentinel hospitals reporting system on all the viral encephalitis (VE) cases identified between June 2005 and May 2007. County Center for Disease Control and Prevention (CDC) investigated the cases, drawing blood and cerebrospinal fluid (CSF) samples from the hospitals, and testing IgM antibody against JE using ELISA. We used Epi Data and Excel for data entry and analysis. RESULTS: A total of 1097 VEs were reported and 1053 (96.0%) had blood or CSF samples collected and tested for IgM antibody against JE. Three hundred and eleven cases (29.5%) showed JE antibody positive (JE confirmed case). Among the JE confirmed cases, numbers of those under 15 year of age accounted for 33.7%, 43.9% and 88.3% in Baoji, Weinan and Ankang prefectures respectively. The rest were mainly children aged 5-14 years old (53.3%). Toddlers,farmers and children accounted for 85.2% in JE confirmed cases. About half of other VE cases (51.0%) were students of all age. Data an investigation on 398 reported VE cases at discharge, showed that 67.1% of JE confirmed cases recovered while 83.7% of the other VE cases fully recovered. The case fatality rates were 9.2% for JE confirmed cases and 3.1% for other VE cases. 578 cases were followed up at 90-days after discharge, 69.6% of JE confirmed cases and 90.2% of other VE cases recovered, with case fatality rates were 13.6% and 3.6% for JE confirmed cases and for other VE cases, respectively. The sequelae rates were 10.0% for JE confirmed cases and 4.5% for other VE cases. CONCLUSION: The peak of the VE season was the same as that of JE. There were 45.6% of reported JE cases with negative JE IgM, suggesting that it is necessary to carry out laboratory testing for clinical diagnosis cases. The fact that high risk population was different at prefectures levels suggested that more attention be paid in JE control and prevention.