成人和儿童接种甲型肝炎灭活疫苗（Vero细胞）安全性和免疫原性研究

目的：评价甲型肝炎灭活疫苗（Vero细胞）在成人及儿童中接种的安全性及其免疫原性。方法选择6-16岁、16岁以上2组人群,采用0、6月免疫程序接种,观察该疫苗的不良反应,抗体阳转率和抗体几何平均滴度（GMT）。结果儿童和成人剂量组局部、全身反应发生率分别为2.83%、3.06%（χ2=0.451,P〉0.05）和10.3%、9.6%（χ2=1.424,P〉0.05）,差异均无统计学意义;免疫后1个月抗体阳转率分别为92.6%、93.5%（χ2=0.959,P〉0.05）,无统计学意义。两针全程免疫1月后两组抗体阳转率均达到100%,抗体几何滴度分别为16583mIU/ml、9762mIU/ml（tT1=1.65,P〉0.05;tT7=1.37,P〉0.05）,差异无统计学意义。结论维罗信甲型肝炎灭活疫苗（Vero细胞）在儿童和成人中应用具有良好的安全性和免疫原性。     

人甲型H7N9禽流感全病毒灭活疫苗和裂解疫苗在小鼠中的免疫原性研究

 目的   比较人甲型H7N9禽流感全病毒灭活疫苗和裂解疫苗在小鼠中的免疫原性,为该疫苗的类型选择提供初步依据。 方法   采用相同血凝素含量（5 μg）的H7N9全病毒灭活和裂解疫苗（含或不含氢氧化铝佐剂共4种类型）,分别对BALB/c小鼠进行1针或2针免疫。免疫后,用血凝抑制（hemagglutination inhibition,HI）试验检测血清抗体滴度,比较不同类型疫苗的免疫效果。 结果   小鼠免疫1针全病毒灭活疫苗后,全部血清阳转,HI抗体几何平均滴度（geometric mean titer,GMT）为149;免疫2针后,抗体GMT为243。小鼠免疫1针裂解疫苗后无抗体阳转;免疫2针后全部抗体阳转,GMT为139。两种疫苗添加铝佐剂后,诱导的HI抗体GMT仅略有增加。 结论   H7N9全病毒灭活疫苗在小鼠中的免疫原性较强。在同样类型和剂量的情况下,裂解疫苗需要免疫两次才能达到与全病毒疫苗相同的效果。铝佐剂对免疫原性提升不明显。     

双价肾综合征出血热纯化疫苗(Vero细胞)在儿童和老年人中的免疫原性观察

目的    评价双价肾综合征出血热纯化疫苗(Vero细胞)在6～15岁儿童和>60岁老年人中的免疫原性。方法   对知情同意的500名6～15岁(儿童组)、16～60岁(成年人组)和>60岁(老年人组)的健康人群按2:1:2的人数比例非随机接种双价肾综合征出血热纯化疫苗(Vero细胞),其中以成年人组作为对照。用ELlSA和空斑减少中和试验测定儿童和老年人接种疫苗后的抗体阳转率和几何平均滴度(GMT)。结果 经ELISA测定,试验组(儿童和老年人)免疫后的抗体阳转率与成年人对照组的差异无统计学意义;老年人组与成年人组的抗体GMT差异无统计学意义,儿童组的GMT水平低于成年人组,差异有统计学意义,但GMT达到有效保护水平。经空斑减少中和试验测定,试验组的抗体阳转率和GMT与对照组的差异均无统计学意义。结论   疫苗对≥6岁的所有健康人群接种(禁忌证除外)均具有良好的免疫效果。     

流行性乙型脑炎减毒活疫苗与灭活疫苗免疫效果及人体接种反应观察

目的:比较乙脑减毒活疫苗和灭活疫苗的免疫效果和安全性。方法:选择光泽县1～2周岁应初免的儿童264名,分组接种乙脑减毒活疫苗和乙脑灭活疫苗,观察人体接种反应,采用细胞蚀斑减少中和试验检测免疫前及免疫后乙脑中和抗体。结果:减毒活疫苗组抗体阳转率和抗体几何平均滴度(GMT)分别为91.30%和1∶20.22;灭活疫苗组为64.38%和1∶16.51。经统计学分析,减毒活疫苗组抗体阳转率和阳性抗体(GMT)均高于灭活组。经观察,减毒活疫苗组和灭活疫苗组人体反应均为发热和接种部位轻度红肿,发热率分别为8.51%和8.13%,中、强反应率为2.13%和0.81%,红肿率为1.42%和0.81%。所有发热及轻度红肿者均于24小时恢复正常。结论:乙脑减毒活疫苗免疫效果好,免疫针次少,安全性好,是现阶段预防乙脑比较理想的疫苗,适宜推广使用。     

流行性感冒灭活疫苗临床研究

兰州生物制品研究所（简称兰州生研所）研制出的流行性感冒灭活疫苗（简称流感疫苗）根据国家关于《新药临床研究批件》要求进行Ⅰ Ⅱ期的临床研究。接种后进行一般反应观察,采用血球凝集抑制试验测定血清中3种抗体滴度,结果反应率为0．81％,HIN1,H3N2和B型抗体阳转率分别为96％,95．7％和98．7％,接种后的血清抗体GMT分别增长39．7％,33．2和45．2倍。该疫苗具有很好的安全性,人体接种后具有较好的免疫原性。     

国产重组酵母乙肝疫苗对成人的免疫效果

目的:了解国产重组酵母乙肝疫苗(YDV)5μg和10μg对成人的安全性和免疫学效果.方法:199例研究对象随机分为2组,分别接受YDV 5μg和10μg,每人每月肌内注射1次,共3次(全程免疫)后1个月,进行免疫效果观察.检测血清乙肝表面抗体阳转率和乙肝表面抗体平均几何滴度(GMT),并观察2组的不良反应.结果:研究对象中未发现中、重度的局部和全身不良反应.接种5μg和10μg疫苗组的乙肝表面抗体阳转率分别为89.25%及98.11%;乙肝表面抗体GMT分别为18.88及54.47mIU·mL-1,2组的GMT差异有显著性(P＜0.05).结论:YDV成人免疫是安全的,10μg YDV抗乙肝表面抗体的GMT明显高于5μg YDV.     

两种剂量重组酵母乙肝疫苗免疫效果比较

目的 为了解不同剂量重组酵母乙肝疫苗封成人免疫效果。方法采用0、1、6月免疫程序，对98位18-40岁健康成人接种5ug和10ug两种剂型重组酵母乙肝疫苗。结果 接种10ug组个别人有轻度反应，5ug组无任何全身和局部反应。两组观察对象于初免后36个月，检测抗-HBS阳转率分别为84．00％、61．22％，抗体GMT滴度为197．53和110．66。结论 接种重组酵母乙肝疫苗后3年采用检测高剂量抗体阳转率和抗体GMT滴度显着高于低剂量组。说明成人接种10ug重组酵母乙肝疫苗免疫效果优于5ug。     

伤寒Vi多糖疫苗和全菌体死疫苗的安全性和免疫原性比较

作者在马来西亚空军新兵中比较了伤寒Vi多糖疫苗和全菌体死 ( WCK)疫苗的安全性和免疫原性。研究采用开放、随机、对照试验 ,研究对象为来自马来西亚不同地区的 2 39名 1 8～ 2 5岁男性新兵 ,其中 1 1 4人接受WCK疫苗 ,1 2 5人接受 Vi多糖疫苗 ,WCK疫苗组在首针接种两周后接受第 2针。记录注射后 72小时内的全身反应 (发热、头痛、全身痛 )和局部反应 (注射部位不同程度的疼痛及红、肿 )。分别于免疫前及接种后 2和 6周采血 ,检测抗 Vi抗体几何平均滴度 ( GMT)和血清阳转率 (抗 Vi抗体滴度比免前增长 4倍以上 )。　　结果表明 ,Vi疫…     

肠道病毒71型灭活疫苗（Vero细胞）接种5年免疫持久性观察

目的 观察肠道病毒71型（enterovirus 71,EV71）疫苗III期临床试验接种5年的免疫持久性。方法 在III期临床试验免疫原性亚组中,对完成全程两针次免疫的免前抗EV71中和抗体阴性人群进行免疫后5年采血并检测抗EV71中和抗体,对0 d、56 d、8个月、14个月、26个月、64个月同时具有抗EV71中和抗体检测数据人群评价免疫持久性。结果 共614名受试者完成5年免疫持久性血样采集并获得中和抗体检测结果,其中490名受试者同时具有0天、56 d、8个月、14个月、26个月、64个月抗EV71中和抗体检测数据,疫苗组和安慰剂对照组分别为235名和255名。EV71疫苗免疫后5年,疫苗组抗EV71中和抗体阳性率（100.00%）和抗体几何平均滴度（geometric mean titer,GMT）（369.57）均高于对照组（69.02%和55.58）。分别以抗体滴度8、16、32为阳性判定标准,疫苗组阳性率（100%、99.57%、97.87%）均高于对照组（69.02%、61.96%、59.61%）。对不同年龄亚组进行分析,6~11、12~35月龄受试者免疫后疫苗组5年抗EV71中和抗体阳性（滴度≥8）率（均为100.00%）和抗体GMT（367.14、370.64）均高于对照组（66.67%、71.27%和53.43、63.66）。在EV71疫苗免疫后的各个时间点,疫苗组抗EV71中和抗体阳性率和GMT均高于对照组。结论 该EV71疫苗两针基础免疫后能够诱导良好的免疫原性,在免疫后5年依然保持较好的免疫持久性。     

不同稀释液配制的结合疫苗免疫持久性研究

目的 了解分别用Al(OH)3佐剂、生理盐水配制Hib结合疫苗和A、C群脑膜炎球菌结合疫苗的免疫持久性.方法 分别用两种稀释液配制Hib结合疫苗和A、C群脑膜炎球菌结合疫苗,各自免疫小鼠,采集分离血清用ELISA测定血清IgG抗体滴度,计算血清抗体GMT和阳转率及不同免疫针次的免疫持久性.结果 两种稀释液配制的Hib结合疫苗和A、C群脑膜炎球菌结合疫苗均可产生明显的抗体应答和免疫记忆反应,但在刺激机体快速产生免疫应答,加强免疫后的回忆反应,抗体滴度及免疫持久性方面有明显差异.生理盐水配制的结合疫苗较Al(OH)3盐水配制的结合疫苗可刺激机体快速产生抗体应答,但Al(OH)3盐水配制的结合疫苗具有更好的抗体GMT和免疫持久性.结论 Al(OH)3盐水配制的结合疫苗具有较好的免疫原性.     

乙型脑炎减毒活疫苗安全性和免疫原性观察

目的 观察乙型脑炎（乙脑）减毒活疫苗的接种反应和免疫原性.方法 分别选择52名（8月龄～50岁）和607名（8月龄～12岁）健康志愿者进行Ⅰ和Ⅲ期临床试验.试验组每人接种1次由上海生物制品研究所有限责任公司研制的乙脑减毒活疫苗（0.5 ml）,对照组接种同样剂量的已上市乙脑减毒活疫苗.两组接种后的不良反应率和中和抗体阳转率用x2检验进行比较,中和抗体几何平均滴度用t检验进行比较.结果 试验组接种后有5.91％的人体温升高,对照组为7.96％,两组的体温反应发生率差异无统计学意义（x^2 =0.917,P=0.338）.试验组Ⅰ期试验局部反应率为1.92％,Ⅲ期试验为0.25％,对照组Ⅲ期试验局部反应率为0.50％,两组的局部反应率差异无统计学意义（确切概率法,P=0.553）.Ⅲ期免疫原性试验中,试验组的血清中和抗体阳转率为89.00％,抗体几何平均滴度为29.69;而对照组分别为74.59％和19.25,差异均有统计学意义（x^2=11.708,P=0.001;t=4.281,P=0.001）.结论 本研究的试验性乙脑减毒活疫苗接种反应轻微,并具有良好的免疫原性.     

Tolerance and immunogenicity of the simultaneous administration of virosome hepatitis A and yellow fever vaccines

BACKGROUND: The purpose of this study was to evaluate the tolerance and immunogenicity of a hepatitis A vaccine using immunopotentiating reconstituted influenza virosomes (IRIV) as adjuvant when administered simultaneously with a yellow fever vaccine (YFV). METHOD: An open prospective trial with two parallel groups was conducted with 105 volunteers to study the effect of these vaccinations on the anti-hepatitis A virus (HAV) antibody response. Half of the volunteers (53) received one dose of IRIV-HAV vaccine (Epaxal) and one dose of live attenuated YFV (Stamaril) on the same day at two different sites. Fifty-six volunteers were given a single injection of IRIV-HAV as a control group. Anti-HAV titers were measured at days 14, 28, months 3, 12, 13, and 24 using a standardized test (Enzymun test Anti-HAV). Neutralizing yellow fever antibodies were measured at days 14 and 28 for the YFV recipients. Regarding vaccine tolerance, the volunteers were asked to record all their adverse reactions on a standard report sheet for the 6 days following the immunization. RESULTS: Seroconversion rates for HAV were 88% after 14 days and 100% after 4 weeks. There was no statistically significant difference between the two groups every time the titers were checked (IRIV-HAV vs HAV only: D14: 81 vs 101; D28: 275 vs 368; M3: 153 vs 169; M12: 117 vs 226; geometrical mean titers (GMT) in mIU/mL). However, lower titers were found among male volunteers, and were not attributable to YFV administration. The seroconversion rates for YFV were 90% after 14 days and 96% after 4 weeks. No serious general side-effects and only mild local reactions were reported. The administration of a booster of IRIV-HAV at 12 months resulted in a 24-fold increase in GMT. CONCLUSION: When needed, the simultaneous administration of the IRIV-HAV and YFV is immunogenic, safe and well-tolerated, as volunteers seroconverted to both antigens, with no cross-interference.     

An open-label,single-arm,phase I study to evaluate the safety and immunogenicity of LBVH0101, a new <Emphasis Type="Italic">Haemophilus influenzae</Emphasis> type b tetanus toxoid conjugate vaccine,in healthy adult volunteers

To evaluate the safety and immunogenicity of a new Haemophilus influenzae type b tetanus toxoid conjugate vaccine, LBVH0101 (LG Life Sciences, Ltd.), an open-label, single-arm, phase I study was conducted in twenty healthy adults aged 19 years or older. The subjects were followed for 1 month after administration of a single dose of the vaccine and serum anti-PRP antibody was measured before and 1 month after administration. Among 20 vaccinated subjects, each 10 subjects (50%) reported at least one local and systemic adverse event within 7 days after the vaccination, respectively. Most of the local and systemic adverse events were mild in intensity and resolved within 7 days. There was no death or treatment-related serious adverse event. Geometric mean titers (GMTs) of anti-PRP antibody before and 1 month after the vaccination were 0.71 μg/mL (95% Confidence Interval [CI]: 0.32–1.58,) and 70.26 μg/mL (95% CI: 46.65–105.82), respectively, demonstrating the GMT of anti-PRP antibody at post-vaccination was approximately 98 times higher than that of pre-vaccination. Taken together, LBVH0101 appeared to be safe and well-tolerated and showed good immunogenicity in Korean healthy adults.     

Safety and immunogenicity of a combined hepatitis B virus-Haemophilus influenzae type B vaccine comprising a synthetic antigen in healthy adults

The combined HB-Hib vaccine candidate Hebervac HB-Hib (CIGB, La Habana), comprising recombinant HBsAg and tetanus toxoid conjugate synthetic PRP antigens has shown to be highly immunogenic in animal models. A phase I open, controlled, randomized clinical trial was carried out to assess the safety and immunogenicity profile of this bivalent vaccine in 25 healthy adults who were positive for antibody to HBsAg (anti-HBs). The trial was performed according to Good Clinical Practices and Guidelines. Volunteers were randomly allocated to receive the combined vaccine or simultaneous administration of HB vaccine Heberbiovac-HB and Hib vaccine QuimiHib (CIGB, La Habana). All individuals were intramuscularly immunized with a unique dose of 10 microg HBsAg plus 10 microg conjugated synthetic PRP. Adverse events were actively recorded after vaccine administration. Total anti-HBs and IgG anti-PRP antibody titers were evaluated using commercial ELISA kits at baseline and 30 days post-vaccination. The combined vaccine candidate was safe and well tolerated. The most common adverse reactions were local pain, febricula, fever and local erythema. These reactions were all mild in intensity and resolved without medical treatment. Adverse events were mostly reported during the first 6-72 hours post-vaccination. There were no serious adverse events during the study. No severe or unexpected events were either recorded during the trial. The combined vaccine elicited an anti-HBs and anti-PRP booster response in 100% of subjects at day 30 of the immunization schedule. Anti-HBs and anti-PRP antibody levels had at least a two-fold increase compared to baseline sera. Even more, anti-HBs antibody titer showed a four-fold increase in 100% of volunteers in the study group. The results indicate that the combined HB-Hib vaccine produces increased antibody levels in healthy adults who have previously been exposed to these two antigens. To our knowledge, this is the first demonstration of safety and immunogenicity for a combined vaccine comprising recombinant HBV and synthetic Hib antigens. The present results support phase I-II clinical trial in the target population, two months old healthy infants.     

Safety and immunogenicity of a new chromatographically purified rabies vaccine in comparison to the human diploid cell vaccine

BACKGROUND: Although human diploid cell vaccine (HDCV) has been available for over two decades and has a proven record of efficacy, it is very expensive to produce and can only be made in small quantities. METHODS: In this trial, we compared the safety and immunogenicity of a new, chromatographically purified rabies vaccine (CPRV) with those of HDCV. One hundred and thirty-five healthy veterinary students were randomized in a 2:1 ratio between CPRV and HDCV respectively. Each student subsequently received an intramuscular injection of 0.5 mL of CPRV or 1mL of HDCV on days 0, 7, and 28, according to the standard preexposure regimen. Local safety data were collected for 7 days following each dose and systemic safety data for 42 days following the first dose. Vaccine administration and safety evaluation were performed by different site personnel. Sera for immunogenicity analysis were collected on days 0 (prevaccination), 28 and 42. RESULTS: All subjects achieved an antirabies antibody titer greater than or equal to the World Health Organization (WHO) accepted threshold level of seroconversion of 0.5 IU/mL after only two of three doses of vaccine in both groups. The geometric mean titers (IU/mL) in the CPRV and HDCV groups respectively were 6.54 (range 0.50 to 64.80) and 10.22 (range 0.70 to 51.40) on day 28, and 40.51 (range 5.40 to 278.00) and 37.71 (range 5.40 to 278.00) on day 42. The percentage of subjects experiencing local reactions within 3 days after any dose ranged from 65.2% to 80.9% in the CPRV group and from 77.3% to 84.4% in the HDCV group. The local reaction reported by the greatest percentage of subjects after each dose was pain/tenderness at the injection site, and most reactions were mild. Most of the reported local reactions resolved within 0 to 3 days postvaccination. Systemic reactions decreased from 76.4% after dose 1 to 36.0% after dose 3 in the CPRV group, and similarly from 55.6% to 31.8% in the HDCV group. For all postdose periods, the systemic reaction reported by the highest percentage of subjects was myalgia. No subjects experienced an immediate local or systemic reaction. CONCLUSIONS: In healthy adults, vaccination with CPRV using a preexposure schedule resulted in a safety and immunogenicity profile similar to that of HDCV.     

Inactivated hepatitis A vaccine in Chinese patients with chronic hepatitis B infection

BACKGROUND: Hepatitis B (HBV)-infected patients have a higher morbidity and mortality when super-infected by hepatitis A (HAV). AIM: To evaluate the immunogenicity and safety of a commercial inactivated HAV vaccine in Chinese patients with chronic HBV infection. METHODS: Sixty-five HBV-infected patients (30 carriers, 22 chronic hepatitis, 13 cirrhosis), who were seronegative for HAV, received a dose of 1440 ELISA units of HAV vaccine at weeks 0 and 24. Twenty-eight healthy individuals aged 18-57 years, who were seronegative for both HBV and HAV infection, also received the same vaccination regimen. Seroconversion was defined as an anti-HAV titre >/= 33 mIU/mL. RESULTS: The seroconversion rates for the HBV-infected patients at weeks 2, 4 and 24 were 72, 91 and 80%, respectively. The corresponding geometric mean titres (GMTs) were 103, 311 and 123 mIU/mL. In the healthy control group the seroconversion rates were 86, 93 and 89% at weeks 2, 4 and 24. The corresponding GMTs were 112, 158 and 250 mIU/mL. There was no difference in the seroconversion rates between the two groups, but healthy controls had a significantly higher GMT at week 24 (P=0.04). Side-effects were more common in HBV patients. CONCLUSION: The HAV vaccine is equally efficacious in patients with chronic HBV infection.     

国产四价流感病毒亚单位疫苗在小鼠体内的安全性和免疫原性

目的  评价国产四价流感病毒亚单位疫苗在小鼠中的安全性和免疫原性。方法  首先，按中国药典2015年版三部的方法对疫苗进行鉴别试验和急性毒性试验。然后，采用随机区组法将40只无特定病原体级雌性昆明小鼠分为4组，每组10只，分别腹腔注射7.5、15.0、30.0 g疫苗和PBS（对照），1.0 ml/只。注射后21 d对小鼠眼眶采血，用血凝抑制法检测小鼠血清抗体水平，并统计抗体阳转率。采用t检验对各组数据进行比较。结果  鉴别试验结果表明疫苗的抗原性与推荐病毒株一致。急性毒性试验显示，疫苗组和对照组小鼠的外观、行为、分泌物、排泄物均无异常，无小鼠死亡。在14 d观察期内，疫苗组和对照组小鼠的体重分别为22.0～33.0和21.8～33.7 g，差异无统计学意义（t=－1.90～1.03，P值均>0.05），且均较免疫前（21.4～23.6和21.2～23.4 g）有不同程度增加。小鼠心、肺、脑、肝等脏器均无明显病理改变。3个剂量疫苗均可诱导小鼠产生较高滴度的血清抗体（1:69～1:998），而对照组仅为1:6～1:25（t=3.68~4.88，P值均<0.01），其中15.0、30.0 g剂量组的抗体阳转率达到100%。结论  四价流感病毒亚单位疫苗具有较好的安全性和免疫原性。     

Safety and immunogenicity of a new fully liquid DTPw-HepB-Hib combination vaccine in infants

We assessed the safety and immunogenicity of a fully liquid, DTPw-HepB-Hib combination vaccine (Quinvaxem) in comparison with separately administered DTPw-Hib and hepatitis B vaccines. Infants participating in this open-label, randomized, phase II study received a primary vaccination course using a 2-3-4 month schedule. Blood samples were taken immediately prior to the first and one month after the third vaccination. Adverse events were assessed over a 7-day post-vaccination period using subject diaries. After completion of the primary vaccination course, 94.7% [95% CI: 89.8-97.7%] of infants receiving the combination vaccine achieved protective anti-HBs antibody titers (> or = 10 mIU/mL) with a mean 39-fold increase in GMTs in comparison with 99.3% [95% CI: 96.3-100%] seroprotection and a mean 29-fold GMT increase in the comparator group. Diphtheria, tetanus and Haemophilus influenzae type b (Hib) seroprotection rates and pertussis seroconversion rates were also similar between the two groups. There was no statistically significant difference in GMTs for diphtheria between the two groups, but significant differences were shown for tetanus, Hib, and pertussis with higher GMTs for each antigen observed in the comparator group. The combination vaccine was well tolerated, with fever (body temperature > or = 38 degrees C) being the most frequently reported adverse event in both the DTPw-HepB-Hib (12.5% [95% CI: 7.7-18.8%]) and comparator (12.6% [95% CI: 7.7-19.0%]) groups. This study demonstrated that the fully liquid DTPw-HepB-Hib combination vaccine has safety and immunogenicity profiles similar to the DTPw-Hib and hepatitis B vaccines when administered separately.     

Safety and Immunogenicity of a High–Potency Inactivated Hepatitis A Vaccine

Background: In recent years, several hepatitis A vaccines have been developed. We wished to evaluate the safety, reactogenicity, and immunogenicity of an inactivated hepatitis A vaccine, containing 1440 EI.U., and to monitor the kinetics of the antibodies monthly for the first year after administration of a single dose of vaccine.
Methods: We conducted an open clinical trial, started in March 1992 and completed in July 1993, at two general hospitals and one pediatric hospital in Antwerp, Belgium, with 194 healthy adult healthcare volunteers. Each volunteer received a single dose hepatitis A vaccine, given intramuscularly at month 0 and a booster at month 12. We undertook serologic follow-up of antihepatitis A virus (antiHAV) antibodies and liver enzymes at day 15 and at months 1, 6, 9, 12, and 13. For a random subgroup of participants, blood samples were taken monthly. In addition, all participants noted local and general symptoms following administration of the vaccine.
Results: This single dose vaccine was well-tolerated; 2 weeks after the vaccination, 80% of the participants had seroconverted (antiHAV antibodies ≥ 20 mlU/mL); after 1 month, seroconversion reached 99% (geometric mean titer (GMT): 383 mlU/mL). One year after the single dose of vaccine, 94% still had antiHAV antibodies above 20 mlU/mL (GMT: 176 mlU/mL). One month afterthe booster dose, seroconversion was 100%, and GMT increased from 176 mlU/mL at month 12 to 4775 mlU/mL at month 13.
Conclusions: The single dose hepatitis A vaccine is safe and highly immunogenic; it gives a rapid antibody production and a rapid increase of GMT. The persistence of protective antibodies until month 12 allows a booster at month 12. This schedule will easily fit into existing travel or occupational health vaccination schedules and will improve vaccination compliance.