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The defects of lack of fusion (LOF) and cracks produced in the process of direct laser deposition 24CrNiMoY alloy steel have a great influence on the mechanical properties of samples. The effects of laser energy area density (EAD) on the distribution and formation mechanism of the LOF and cracks are studied by TEM, EBSD, SEM, OM, laser confocal microscopy (LCM) and macroscopic stereo microscope (MSM). The results show that different EADs have an important influence on the formation and elimination of defects in direct laser deposition 24CrNiMoY alloy steel sample. When the EAD is 67 J/mm2, the wettability is adverse, the molten pool parameters do not satisfy the complete fusion formula, and the LOF defects occur in the samples. However, as the number of deposition layers increases, the proportion of LOF defects decrease. When the EAD is increased to 78 J/mm2, thermal stress causes the liquid film to rupture and inclusion cracking, and cracks appear in the sample. However, when the EAD is 72 J/mm2, due to good liquid flow in the molten pool, the solid–liquid phase wettability is increased and elemental segregation is weakened. Meanwhile, the thermal stress in the sample is moderate. Therefore, the sample without LOF defects and cracks is prepared, and the sample has the best microhardness (386 HV) and tensile properties (ultimate tensile strength is 788 MPa; elongation is 9.1%), which lays a foundation for the preparation of defect-free 24CrNiMoY alloy steel samples by direct laser deposition.

To more accurately analyze the atomization process of vacuum induction melting gas atomization (VIGA) technology at high gas pressure, a new method was proposed based on the combination of VOF and DPM theories. Numerical simulations and powder preparation tests were used to verify the applicability of this method. The results indicated that the large eddy simulation model could accurately visualize the large droplet separation process from the liquid column in the primary atomization. Additionally, the TAB model was used to predict the particle size distribution in the secondary atomization. The simulated results were consistent with the powder preparation test. 24CrNiMoY alloy steel powder prepared at 9.0 MPa had the highest flowability and apparent density. The powder is suitable for selective laser melting technology. This research is of guiding significance and serves as a methodological reference for understanding the atomization process of VIGA technology.

Long noncoding RNA (lncRNA) have been reported to be crucial regulators for carcinogenesis, including rectal cancer. This work aimed to explore the roles and associated mechanisms of small nucleolar RNA host gene 17 (SNHG17) in rectal cancer. A quantitative real-time polymerase chain reaction was performed to measure the expression level of SNHG17 in rectal cancer tissues and cells. Cell counting kit-8 (CCK-8) assay and flow cytometry assay were conducted to measure the biological roles of SNHG17 in rectal cancer. In addition, luciferase activity reporter assay, RNA immunoprecipitation (RIP) assay, and rescue experiments were conducted to explore the mechanisms of SNHG17 in rectal cancer. The upregulation status of SNHG17 was identified in rectal cancer tissues and cells. Functionally, knockdown the expression of SNHG17 inhibits rectal cancer cell proliferation via stimulating cell apoptosis. In vivo assay showed that the knockdown of SNHG17 inhibits tumor growth. Furthermore, we showed that microRNA-361-3p (miR-361-3p) has decreased expression in tumor tissues and cells, and SNHG17 functions as a sponge for miR-361-3p. The upregulation status of stanniocalcin 2 (STC2) was also found in rectal cancer, and the knockdown of STC2 hinders cancer progression. In conclusion, lncRNA SNHG17 functions as an oncogenic lncRNA in rectal cancer by regulating the miR-361-3p/STC2 axis.

COVID-19 vaccines from multiple manufacturers are needed to cope with the problem of insufficient supply. We did two single-center, randomised, double-blind, placebo-controlled phase 1 and phase 2 trials to assess the safety, tolerability and immunogenicity of a recombinant COVID-19 vaccine (Sf9 cells) in healthy population aged 18 years or older in China. Eligible participants were enrolled, the ratio of candidate vaccine and placebo within each dose group was 3:1 (phase 1) or 5:1 (phase 2). From August 28, 2020, 168 participants were sequentially enrolled and randomly assigned to receive the low dose vaccine, high dose vaccine or placebo with the schedule of 0, 28 days or 0, 14, 28 days in phase 1 trial. From November 18, 2020, 960 participants were randomly assigned to receive the low dose vaccine, high dose vaccine or placebo with the schedule of 0, 21 days or 0, 14, 28 days in phase 2 trial. The most common solicited injection site adverse reaction within 7 days in both trials was pain. The most common solicited systematic adverse reactions within 7 days were fatigue, cough, sore throat, fever and headache. ELISA antibodies and neutralising antibodies increased at 14 days, and peaked at 28 days (phase 1) or 30 days (phase 2) after the last dose vaccination. The GMTs of neutralising antibody against live SARS-CoV-2 at 28 days or 30 days after the last dose vaccination were highest in the adult high dose group (0, 14, 28 days), with 102.9 (95% CI 61.9–171.2) and 102.6 (95% CI 75.2–140.1) in phase 1 and phase 2 trials, respectively. Specific T-cell response peaked at 14 days after the last dose vaccination in phase 1 trial. This vaccine is safe, and induced significant immune responses after three doses of vaccination.

Background: To evaluate the persistence of antibody for 10 years, and investigate the effect of one or two booster doses with Kanghua human diploid cells rabies vaccine (HDCV) in China. Methods: Participants were re-recruited at year 10 post the primary phase 3 clinical study. Some of them in Kanghua HDCV group who had been boosted one dose at year 8, received one more dose at this boosted study. Participants who never boosted were randomly assigned to boost 1 or 2 doses of Kanghua HDCV. Blood samples were collected at day 0, 1, 3, 7, and 14. Safety was evaluated from day 0–14. Results: At year 10 after primary vaccination, the seroconversion rates of neutralizing antibody were 98.28–100% in Kanghua and Pasteur groups. After booster, the seroconversion rate in each group reached to 100% from day 7 to day 14. GMCs were similar in the groups with the same booster doses, and two doses of booster induced higher levels of antibody. The reported rates of solicited local and systemic adverse reaction were low, and no serious adverse events were found through the boosted study. Conclusion: 5 doses of Kanghua HDCV maintained long-term immunity at least 10 years. One or two doses of booster, rapidly triggered 100% protection against rabies virus. Trial registration: ClinicalTrials.gov: NCT03774628

24CrNiMoY alloy steel samples were fabricated by selective laser melting (SLM), and a phase transformation model was established to study the alloy steel microstructural evolution. Meanwhile, microhardness and tensile properties of 24CrNiMoY alloy steel prepared by different laser energy densities (Ev) were investigated. Results indicate that the microstructural evolution of 24CrNiMoY alloy steel is consistent with the phase transformation model. The main microstructure changed from martensite to bainite with the increase in thermal cycle numbers. In addition, a suitable Ev plays an important role in refining the bainite structure and improving the alloy steel properties. When the Ev decreases from 210 to 140 J/mm3, the bainite lath width reduces from 1.7 to 0.6 μm. Simultaneously, the relative density, tensile strength and microhardness of the fabricated samples increase first and decrease later. 24CrNiMoY alloy steel sample prepared by 160 J/mm3 has fine mechanical properties: The tensile strength is 850 MPa and microhardness is 360 HV0.2.

24CrNiMoY alloy steel used for brake disc was prepared by high power selective laser melting (HP-SLM) in order to increase the productivity. In this work, the microstructure and mechanical properties of as-fabricated part were characterized. Effects of the location of as-fabricated 24CrNiMoY part (top, middle and bottom) and scanning speed on microstructure evolution were studied. The results of this work indicated that the as-fabricated part microstructure mainly consisted of granular bainite and lath bainite. Demonstrating that bainite was obtained by a large temperature gradient and sufficient holding time by experiment. With increasing scanning speed, the size d B of the bainitic ferrite lath beam spacing and the size ∅ B of the mixed structure of polygonal ferrite and quasi-polygonal ferrite were gradually refined and larger, respectively. The HP-SLM-produced parts were dominated by high-angle (>15°) grain boundaries (HAGBs) and the contents of HAGBs decreased at first while increased (62.3%, 63.5%, 50.1%) when scanning speed varied from 5 to 9mm/s. Supersaturated solid solution, dislocation, and subgrain cell structure, which results in a high microhardness and fine strength.

The Arthus reaction is a rare adverse reaction that usually occurs after vaccination with large and more severe local reactions, belonging to type Ⅲ hypersensitivity reaction. This reaction is characterized by pain, swelling, induration (Tissue that becomes firm) and edema, even accompanied by severe necrosis or ulceration at the injection sites. However, most of mild cases generally can be cured without treatment, and only severe cases need to be treated with anti-allergy. Therefore, this adverse reaction is often ignored by people. We searched PubMed, Web of Science and Chinese database (CNKI database and Wan Fang database) for published studies using the terms “Arthus reaction” or “Arthus phenomenon”, combined with “vaccine”, with no date or language restrictions for all publications before January 28, 2019. Only 30 cases of Arthus reaction were found, of which only one case died.4 cases of Arthus reaction post-dose-1 were reported in the review. The proportion of Arthus reaction occurred after the first, second and third injections in those case reports was 13.3%, 50.0%, and 23.3%, respectively. Arthus reaction was determined according to the clinical symptoms (The symptoms which were observed by the researchers, such as red, swelling and painful with itching at or around the injection sites). The specific causes of Arthus reaction after one dose of vaccination are not described in detail in literatures. Therefore, it could be hypothesized that the case has a pre-existing specific IgG (Such as pre-existing antibody, etc.) to cause the Arthus reaction. And 17 reported cases were observed in children younger than 6 y. In addition, we collected only 18 cases of bacterial vaccine-induced Arthus reaction and 12 cases of viral vaccines. However, there are no other data (Such as the total number and incidence rate of vaccination) in literatures, so we cannot compare statistically significant differences. At presents, no previous reviews of vaccine-induced Arthus reaction have been found. Thus, a systematic review about vaccine-associated Arthus reaction is urgently needed to deepen people‘s understanding and concern of this phenomenon. In this manuscript, we retrospectively reviewed the description of the discovery process and mechanisms of Arthus reaction, a description of the characteristics of Arthus reaction cases, reporting the Arthus reaction cases in China during 2010–2015, diagnostic criteria and general treatment, preventive measures of Arthus reaction, and challenges remaining to be investigated in the future.

24CrNiMo alloy steel samples for preparing the brake disc of high-speed train were fabricated by direct laser deposition (DLD) with different laser energy area density (EAD). The effect of various energy area densities on the distribution, size and mechanism of pores, slag inclusions and cracks in the DLD 24CrNiMo alloy deposition layer were investigated. The results show that the increase of the EAD leads to the increase of the dilution index and area of the molten pool. The density of multilayer samples reached highest (99.25%) when the EAD was 100 J/mm2. The morphology of pores had irregular deformation when the EAD was low while had smooth sphere morphology when the EAD was high. The cracks ratio increased with the increase of the EAD while the content of inclusion defects decreased. A behavioural process for the re-melting of pore defects at different energy densities was discussed, and the formation of inclusion defects with low EAD was studied to illuminate the EAD effects on defects. The samples deposited at the 100 J/mm2 have no obvious defects and relatively high density, this EAD can be considered as a reference to prepare 24CrNiMo samples with low defects by DLD.

Nickel-based K417G superalloy powder is the main material used in laser additive manufacturing (LAM) of aerospace engine turbine blades. In this study, K417G powder was prepared by the vacuum induc...

24CrNiMo alloy steel used for brake disc was prepared by selective laser melting technology with the processing parameters of high power input and thicker powder layer. The Microstructure and mechanical properties of as-fabricated part were characterized. Effects of processing parameters on the production efficiency, thermal history and microstructure evolution mechanism were studied. The results of this work indicate that the as-fabricated steel microstructure mainly consist of granular bainite and meta bainite, which results in a high microhardness and fine strength. High laser power input leads to a high thermal accumulation level in a SLM process and the microstructure mainly transforms into bainite. In addition, compared to the commonly used parameters, the overall preparation efficiency in this study is enhanced by 82.9%. These presented results provide an insight on how to improve SLM efficiency, and preparation of high-performance 24CrNiMo alloy steel by SLM technology shows high potential for manufacturing of the brake disc core part.

Background: The test-negative design has been used widely in evaluation of various vaccines' effectiveness, such as influenza, rotavirus, and so on. Recently, there have been some studies about EV-71 vaccine effectiveness by using test-negative design(TND). However, the validity of the TND application in EV-71 vaccines has not been evaluated. Methods: This study is set upon prior methods to evaluate the validity of TND for influenza vaccine by using a randomized controlled clinical trial database. Vaccine effectiveness estimated by TND (VE-TND) in modified intention-to-treat population (mITT) and per-protocol-set population(PPS) was derived from a large randomized placebo-controlled clinical trial (RCT) of inactivated monovalent EV-71 vaccine in China. Derived VE-TND estimates were compared to the original vaccine efficacy results in RCT (VE-RCT). Results: We totally enrolled 7325 participants who seeked medical care for suspected EV-71 infected diseases during the surveillance. There are no significant differences between cases(test-positive) and controls(test-negative) on sex, age, height, and weight. TND vaccine effectiveness estimates were similar to original RCT vaccine efficacy estimates, both in modified intention-to-treat population and per-protocol populations. Conclusions: This study supports that TND, as an appropriate observational study design is valid to measure EV-71 vaccine effectiveness.

BackgroundCalponin was first defined as a striated muscle troponin T-like protein that binds actin thin filaments to regulate smooth muscle contraction. There are few studies of CNN1 and CNN2 in colorectal cancer, and the roles these two genes play in colorectal cancer cell lines and the mechanisms by which they act are unknown.MethodsWe used immunohistochemistry to identify expression of the two genes in the cancer tissues. RT-PCR was used to measure expression levels of microRNA. W performed western blots to measure changes in signaling pathways in the context of expression interference.Meanwhile, the same method was used to measure binding relationship between the two genes and key pathway proteins. To determine the relationship between microRNA and gene mRNA, we used the reporter gene method. We used the chi-square and t-test methods to analyze the significance and correlations of the data.Results and conclusionsExpression levels of CNN1 were lower in colon cancer tissues than in normal mucosal tissues. After downregulating CNN1, the cell cycle in colon cancer cell lines progressed quickly, and the expression of related pathway proteins also increased. Expression levels of CNN2 were higher in colon cancer tissues, and its downregulation significantly inhibited cell cycle progression in colon cancer cell lines. We confirmed correlations between the expression of microRNA and CNN2 using data analysis.Bars indicate ± standard errors.*p < 0.05; **p < 0.01 compared with the control. The inhibition of the expression of CNN2 mRNA using microRNA was confirmed using western blot. The combination of the two at the mechanism level was also demonstrated using the reporter gene method.

Effect of different TA15 powder additions on high temperature oxidation kinetics of pre-laid laser melting 45CrNiMoY alloy steel was studied. Thermogravimetric method was used to determine the kinetics curve of constant temperature oxidation of alloy steel sample at 700℃. The results show that bainite and acicular ferrite are the main microstructures of alloy steel after adding TA15 powder. With the increase of TA15 powder, the microstructures showed a distinct trend of refinement. The oxidation kinetics curves of alloy steels follow the linear law. The alloy steels with 1.0 wt.% TA15 powder have the best resistance to high temperature oxidation, and the oxidation rate constant is 1.48×10-4 mg2·cm-4·h-1. Particle reinforcement phase formed in alloy steel can provide pinning effect for oxide film, while micro-cracks added in excess TA15 alloy steel sample are not conducive to the improvement of high temperature oxidation resistance.

TA15 titanium alloy powder was prepared by Electrode Induction Melting Gas Atomization (EIGA) method at different gas pressure. The breakup behavior of molten droplet in the primary and secondary breakup process was analyzed. Also, the properties of TA15 fine powder prepared at optimized gas pressure were tested. Results shown that gas pressure played a positive role on the transformation between large size oval metal flake and regular molten stick in primary breakup process. After then, the molten stick followed three kinds of breakup modes and turned to disparate shape powders in secondary breakup process, which were normal necking down breakup mode, interfere breakup mode and impact breakup mode. At 6MPa pressure, simulation shown that the back-flow area had the largest volume and the average velocity on the flow field axis reached to 260 m/s. The preparation rate of fine TA15 powder was 82% and had the narrow particle size distribution. The phase of fine powder prepared at 6MPa was all the α-Ti phase. Flow ability and apparent density were 22.1s/50 g and 2.82 g/cm 3 respectively, which was conformed to the ASTM test standard and was in line with the requirement for Laser 3D printing.

With a profusion of network applications, traffic classification plays a crucial role in network management and policy-based security control. The widely used encryption transmission protocols, such as the secure socket layer/transport layer security (SSL/TLS) protocols, lead to the failure of traditional payload-based classification methods. Existing methods for encrypted traffic classification cannot achieve high discrimination accuracy for applications with similar fingerprints. In this paper, we propose an attribute-aware encrypted traffic classification method based on the second-order Markov Chains. We start by exploring approaches that can further improve the performance of existing methods in terms of discrimination accuracy, and make promising observations that the application attribute bigram, which consists of the certificate packet length and the first application data size in SSL/TLS sessions, contributes to application discrimination. To increase the diversity of application fingerprints, we develop a new method by incorporating the attribute bigrams into the second-order homogeneous Markov chains. Extensive evaluation results show that the proposed method can improve the classification accuracy by 29% on the average compared with the state-of-the-art Markov-based method.

Ebola virus disease (EVD) has become a great threat to humans across the world in recent years. The 2014 Ebola epidemic in West Africa caused numerous deaths and attracted worldwide attentions. Since no specific drugs and treatments against EVD was available, vaccination was considered as the most promising and effective method of controlling this epidemic. So far, 7 vaccine candidates had been developed and evaluated through clinical trials. Among them, the recombinant vesicular stomatitis virus-based vaccine (rVSV-EBOV) is the most promising candidate, which demonstrated a significant protection against EVD in phase III clinical trial. However, several concerns were still associated with the Ebola vaccine candidates, including the safety profile in some particular populations, the immunization schedule for emergency vaccination, and the persistence of the protection. We retrospectively reviewed the current development of Ebola vaccines and discussed issues and challenges remaining to be investigated in the future.

Introduction. The biological roles of microRNA-654-5p (miR-654-5p) in cancers have been previously reported. However, its role in colorectal cancer (CRC) remains largely unknown. The purpose of this work was to investigate the roles and associated mechanisms in CRC.Methods. Quantitative Real-Time PCR (qRT-PCR) was utilized to explore the expression pattern of miR-654-5p in CRC cells. Cell Counting Kit-8 (CCK-8) assay, wound-healing assay, and transwell invasion assay were conducted to investigate the effects of miR-654-5p on CRC cell proliferation, migration, and invasion, respectively. Moreover, the mechanisms behind miR-654-5p regulates CRC progression were investigated.Results. Compared with normal cell line, miR-654-5p expression level was significantly suppressed in CRC cells. After overexpression of miR-654-5p, the malignancy behaviors of CRC cells including cell proliferation, migration, and invasion were remarkably decreased. Subsequently, we found hematopoietic cell-specific protein 1-associated protein X-1 (HAX-1) was a putative target for miR-654-5p. Rescue experiments showed overexpression of HAX-1 could partially reversed the effects of miR-654-4p on CRC cell events.Conclusion. miR-654-5p was reduced expression in CRC cells and could regulate CRC progression via targeting HAX-1.

The precise laser displacement sensor monitoring system during direct laser deposition process was established. The two-dimensional and three-dimensional topography images were acquired through data analysis and point cloud reconstruction method. The results of monitoring system show that with the increasing of scanning speed from 2 mm/s to 6 mm/s, the width of single track deposition kept stable due to the laser energy distribution, and the height of deposition decreased from 1.59 mm to 0.33 mm. The relationship between scanning speed and deposited 24CrNiMo alloy topography was established through data fitting. Deposition surface convex and concave defects can be distinguished through the feature of three dimensional images, uneven surface mainly existed in the deposition sides, which was represented by blank zone of acquired images. With the scanning speed increasing, the surface quality of deposited samples improved while the depositing efficiency decreased. The formation of surface defects is related to the solidification speed of molten pool, the phase structure of single track deposition was martensite owing to the high solidification speed, and the martensite has strain along the block boundary. The solidification rate increased with scanning speed increased, which led to the less time in forming surface defects.

Based on the principle of in-situ precipitation strengthening, TA15 powder (Ti-6.5Al-1Mo-1V-1.5Zr) was used as an additive to improve the mechanical properties of 45CrNiMoY alloy steel by pre-laid laser cladding (PLLC) technology. Effects of the content of TA15 powders (0–1.5 wt%) on the microstructure, precipitation mechanism and mechanical property of PLLC 45CrNiMoY alloy steel samples were investigated. Results indicate that TA15 alloy has a significant effect on the microstructure of 45CrNiMoY alloy steel through metallurgical reaction in the laser molten pool. With the increase of TA15 powder content, the granular bainite (GB) microstructure were remarkably refined, the mount of the acicular ferrite (AF) was increased, and in-situ precipitates such as Ti-Y2O3-Zr (TYZ) composite oxide, TiC and ZrC carbide were produced. The 45CrNiMoY alloy steel sample with 1.0 wt% TA15 alloy addition has the best combination of tensile strength (1158 ± 9.7 MPa) and elongation (9.8 ± 0.4%), its microhardness was improved by 25.6% compared with the sample without TA15 powder. The TYZ composite oxides did not only serve as the AF nucleation sites but also spheroidize the detrimental manganese sulfide phase leading to a good elongation of the 45CrNiMoY alloy steel, the TiC and ZrC carbides played a key role in the improvement of the microhardness and tensile strength. The proper addition of TA15 powder can effectively improve the microstructure and mechanical properties of the PLLC 45CrNiMoY alloy steel.

In order to effectively eliminate the crack initiation, reduce the amount of pores and improve the structure of large alloy steel parts with high-performance, the direct laser deposited (DLD) technique was used to prepare the 24CrNiMoY alloy steel samples by laser depositing power of 2000W and scanning speed of 6 mm/s at 100 °C,150 °C, 200 °C, 250 °C preheating temperatures, respectively. The structure and properties of the samples were studied using OM, SEM, XRD, TEM, EBSD, hardness tester and tensile tester. The results showed that with the increase of preheating temperature, the cracks in deposited alloy steel samples were removed, and the amount of pore was significantly reduced. The structure of the samples were mainly composed of granular bainite (GB) and lath bainite (LB), the content of LB was reduced from 95.7% to 3.5% with the increase of preheating temperature because GB played a segmentation role to LB. When the preheating temperature was 200 °C, the deposited sample with GB (34.7%) and LB (65.3%) had the most uniform microhardness distribution, the highest microhardness of 414 HV0.2, and the best match of strength and toughness with the tensile strength of 1051 MPa and the elongation of 7.4%. The proper preheating temperature of 200 °C can effectively eliminate the crack, decrease the pores and significantly improve the structure and properties of the DLD 24CrNiMoY alloy steel.

The unique thermal behavior during the multi-layer laser rapid manufacturing process brings about unique microstructure for the as-produced parts. In this paper, a comprehensive three-dimensional self-consistent transient temperature field model of 24CrNiMoY alloy steel by pre-laid laser cladding technology (PLLC) was established, and the reliability of model was verified by the experiment. The simulation results showed that as scanning speed increased (5, 7, 9 mm/s), the peak temperature, dimensions and liquid lifetime of the molten pool decreased, while the G × R increased and G/R decreased at the same position. With increasing layer, the peak temperature of molten pool and the temperature of the whole domain increased gradually until forming a dynamic balance. The contrast experimental results showed that with scanning speed increased, the average size of equiaxed grain increased (4.682, 5.012, 5.462 μm) and the average aspect ratio of columnar grain decreased (11.890, 11.411, 10.593). During the multi-layer process, grain growth modes were different along the deposition sections. The structure in parallel scanning direction mainly consisted of equiaxed grains, while in the overlapping direction were equiaxed and columnar grains. There was a clear columnar-to-equiaxed transition (CET) boundary that controls the change in grain types. The grain growth behavior of a multi-layered in vertical scanning direction section was different from that of a single track. All the above results illustrated that temperature field had a significant effect on the thermal behavior during PLLC process, which affected the grain evolution of 24CrNiMoY alloy steel.

BACKGROUND This study evaluated the 2-year efficacy, immunogenicity, and safety of the Vigoo enterovirus 71 (EV71) vaccine. METHOD In an initial phase 3 study, we randomly assigned healthy infants and children aged 6-35 months (ratio, 1:1) to receive 2 doses of either EV71 vaccine (5120 participants) or placebo (5125 participants) at days 0 and 28, and followed them for 12 months after vaccination. In this extended follow-up study, we continued to evaluate the efficacy, immunogenicity, and safety of the EV71 vaccine for up to 2 years. RESULTS Overall efficacy was 94.84% (95% confidence interval [CI], 83.53%-98.38%) during the 2-year follow-up period (P < .0001), and the vaccine efficacy during the second year was 100.00% (95% CI, 84.15%-100.00%) against EV71-associated hand-foot-and-mouth disease (HFMD; P < .0001). Geometric mean titers of neutralizing antibody in participants remained high during the 2-year follow-up period, and no vaccine-related serious adverse events were recorded. CONCLUSIONS Two doses of Vigoo EV71 vaccine could provide sustained protection against EV71-associated HFMD in healthy Chinese children. CLINICAL TRIALS REGISTRATION NCT01508247.