Studies with inactivated equine influenza vaccine. 1. Serological responses of ponies to graded doses of vaccine.

Serological responses to three bivalent aqueous equine influenza vaccines of different potency and an adjuvanted bivalent vaccine containing inactivated A/equine/Prague/56 (H7N7) and A/equine/Miami/63 (H3N8) viruses, were examined in seronegative ponies. Potencies of the vaccines, measured by single-radial-diffusion tests, ranged from 4 to 56 micrograms of haemagglutinin (HA) antigen activity/virus strain per dose. Serological responses to vaccination were examined by haemagglutination-inhibition (HI) and single-radial-haemolysis (SRH) tests. Four weeks after a primary dose, HI responses to both vaccine viruses were barely detectable; after a second dose the HI responses to A/Miami/63 virus were low or undetectable but HI responses to A/Prague/56 virus were higher (17/20 ponies with titres greater than or equal to 1:16). In contrast SRH tests revealed dose-related antibody responses to both virus strains after one and two vaccine doses; levels after the second dose were 2- to 5-fold higher than after the primary dose. Highest post-vaccination antibody titres were obtained with the adjuvanted vaccine which contained 2- to 4-fold less antigen (13-23 micrograms HA) than the most potent aqueous vaccine. Post-vaccination antibody reacted well in SRH tests with recent antigenic variants of equine influenza virus. A remarkable finding was the high rate of decline in antibody, detected by HI or SRH tests, following one or two doses of vaccine. Even in animals with the highest post-vaccine antibody levels 2-4 weeks after a booster dose, antibody levels had declined to low or indetectable levels 14 weeks later. The low antibody titres detected at 14-32 weeks after vaccination were nevertheless vaccine dose-related.     

Studies with inactivated equine influenza vaccine. 1. Serological responses of ponies to graded doses of vaccine

Serological responses to three bivalent aqueous equine influenza vaccines of different potency and an adjuvanted bivalent vaccine containing inactivated A/equine/Prague/56 (H7N7) and A/equine/Miami/63 (H3N8) viruses, were examined in seronegative ponies. Potencies of the vaccines, measured by single-radial-diffusion tests, ranged from 4 to 56 micrograms of haemagglutinin (HA) antigen activity/virus strain per dose. Serological responses to vaccination were examined by haemagglutination-inhibition (HI) and single-radial-haemolysis (SRH) tests. Four weeks after a primary dose, HI responses to both vaccine viruses were barely detectable; after a second dose the HI responses to A/Miami/63 virus were low or undetectable but HI responses to A/Prague/56 virus were higher (17/20 ponies with titres greater than or equal to 1:16). In contrast SRH tests revealed dose-related antibody responses to both virus strains after one and two vaccine doses; levels after the second dose were 2- to 5-fold higher than after the primary dose. Highest post-vaccination antibody titres were obtained with the adjuvanted vaccine which contained 2- to 4-fold less antigen (13-23 micrograms HA) than the most potent aqueous vaccine. Post-vaccination antibody reacted well in SRH tests with recent antigenic variants of equine influenza virus. A remarkable finding was the high rate of decline in antibody, detected by HI or SRH tests, following one or two doses of vaccine. Even in animals with the highest post-vaccine antibody levels 2-4 weeks after a booster dose, antibody levels had declined to low or indetectable levels 14 weeks later. The low antibody titres detected at 14-32 weeks after vaccination were nevertheless vaccine dose-related.     

Comparison of the safety and immunogenicity of hepatitis B virus surface antigen co-administered with an immunostimulatory phosphorothioate oligonucleotide and a licensed hepatitis B vaccine in healthy young adults

BACKGROUND: Many individuals do not respond to a three-dose series of hepatitis B vaccine (HBV) and most do not achieve a protective antibody response until after dose 2 or 3. METHODS: Healthy, seronegative 18-28 year old adults were randomly assigned in equal numbers to receive two doses of the experimental vaccine (HBV-ISS without alum) (0, 8 weeks) and placebo (24 weeks) or Engerix-B (0, 8, 24 weeks). Adverse events were collected during the first week and at 4 weeks after each injection. Antibodies were measured 4 weeks after dose 1; before, 1 and 4 weeks after dose 2, and before, 1 and 4 weeks after dose 3 and at 1 year. RESULTS: Ninety-nine participants were enrolled (65% female; mean age 22.6 years). 79% of HBV-ISS and 12% of Engerix-B recipients had a protective antibody response 4 weeks post dose 1 (geometric mean concentration [GMC] 23.0 and 1.87 mIU/mL, respectively). By 1 week post dose 2, 100% of HBV-ISS and 18% Engerix-B recipients had protective levels (GMC 1603 versus 2.40 mIU/mL). Rates of adverse events were low and similar in both groups; headache and fatigue were the most common systemic adverse events in up to 1/3 of both groups. Mild injection-site tenderness was more common after HBV-ISS than Engerix-B after both doses (74-77% compared to 34-58%; p相似文献   

炭疽减毒活疫苗免疫小鼠的最佳剂量筛选

目的本文研究了炭疽减毒活疫苗免疫小鼠的最佳安全、有效剂量,为进一步在小鼠体内进行多疫苗联合接种的安全性和有效性研究提供理论依据。方法将炭疽疫苗分为4个剂量组,经皮下接种小鼠,每周采集尾血。采用ELISA间接法检测血清中特异性抗-PAIgG抗体和抗芽孢IgG抗体;以体重、免疫反应、血液学指标以及病理学等指标对疫苗的安全性和有效性进行评价。结果疫苗接种后,小鼠能够对各剂量产生免疫反应,1／5和1／10剂量组能诱导较高、较快血清抗体滴度的增加,免疫12周后,血清抗体效价仍维持在较高的水平,而1／20和1／40剂量组抗体滴度相对较低,各个剂量组间抗体水平存在统计学差异（P〈0．05）。结论1／10人用剂量组是安全和有效的最佳剂量,可作为炭疽疫苗与其他疫苗联合接种或炭疽疫苗改进的小鼠实验用量。     

Immunogenicity and safety of a DTaP-IPV//PRP approximately T combination vaccine given with hepatitis B vaccine: a randomized open-label trial

OBJECTIVE: To determine seroprotection and vaccine response rates produced by a diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae type-b conjugate (DTaP-IPV//PRP approximately T) vaccine containing a polyribosyl-ribitol-phosphate (PRP)-tetanus toxoid conjugate (Pentaxim) and given with a hepatitis B vaccine. METHODS: In this multicentre open-label trial, 424 infants who received DTaP-IPV//PRP approximately T at 6, 10 and 14 weeks of age were also randomized to receive hepatitis B vaccine at either 6, 10 and 14 weeks or 0, 6 and 14 weeks of age. Antibody levels were determined at 6 and 18 weeks of age, and reactogenicity was monitored using parental reports. FINDINGS: Immunogenicity was high for all vaccine antigens and was similar to that in a historical control study. After primary vaccination, 98.7% of all infants had an anti-PRP antibody titre > 0.15 microg/ml. Seroprotection against poliovirus type-1, -2 and -3 and tetanus was obtained in all infants, and against diphtheria, in 97.1%. Pertussis seroconversion, defined as a > fourfold increase in antibody titre, occurred in 95.3% for anti-pertussis toxoid antibody and in 89.0% for anti-filamentous haemagglutinin antibody. The hepatitis B seroprotection rate was 99.5% with administration at 0, 6 and 14 weeks, and 97.8%, at 6, 10 and 14 weeks. However, the antibody titre was higher with the 0, 6 and 14-week schedule (601 mIU/ml versus 207 mIU/ml). The reactogenicity of both vaccines was low. CONCLUSION: The DTaP-IPV//PRP approximately T vaccine was highly immunogenic. The anti-hepatitis B antibody response was seroprotective with both schedules, though the antibody titre was higher with the 0, 6 and 14-week schedule.     

Human IgG subclass responses in relation to serum bactericidal and opsonic activities after immunization with three doses of the Norwegian serogroup B meningococcal outer membrane vesicle vaccine

Ten adult volunteers, with low prevaccination levels of serum IgG antibodies against meningococcal antigens (< 1 microg ml(-1)), received three doses of the Norwegian group B meningococcal outer membrane vesicle (OMV) vaccine intramuscularly at weeks 0, 6 and 46. Anti-OMV IgG subclass responses were measured and compared with serum bactericidal activity (SBA) and opsonic activity against the vaccine strain 44/76. All vaccinees showed an IgG1 antibody response after each vaccine dose. The vaccine-induced median serum IgG1 antibody levels were 16, 17 and 18 microg ml(-1) 2-6 weeks after the first, second and third dose, respectively. Three vaccinees showed a weak IgG3 response after the first dose, whereas 8 and 9 showed a response after the second (median = 10 microg ml(-1)) and third dose (median = 10 microg ml(-1)), respectively. Low levels of anti-OMV IgG2 antibodies were found, whilst specific IgG4 antibodies were only detected for one vaccinee. The vaccine induced at least a fourfold increase in SBA titre in 8 vaccinees after the first dose, in 9 vaccinees after 2 doses and in all vaccinees after 3 doses. A positive correlation was found between IgG1 subclass antibody levels and SBA (r = 0.62, P < 0.0001). Elevated opsonophagocytic activity, measured as respiratory burst (RB), was observed in all vaccinees after one vaccine dose and usually increased after 2 and 3 doses. A strong positive correlation was found between IgG1 antibody levels and RB (r = 0.76, P < 0.0001). In conclusion, we have shown that systemic meningococcal OMV vaccination in adult vaccinees mainly induced IgG1 antibodies which correlated with bactericidal and opsonic activity, but also a considerable amount of IgG3 antibodies, which, in contrast to the IgG1 response, was induced only after 2 or 3 vaccine doses and declined more rapidly.     

Long-term antibody levels and booster responses in South African children immunized with nonavalent pneumococcal conjugate vaccine

Children who had initially received three doses of either a nonavalent pneumococcal conjugate vaccine containing serotypes 1, 4, 5, 6B, 9V, 14, 18C, 19F, and 23F or placebo at 6, 10, and 14 weeks of age were bled at 9 and 18 months for determination of antibody concentrations. The children were then randomized to receive a booster dose of either the 9-valent pneumococcal conjugate vaccine or a 23-valent polysaccharide vaccine and antibody levels determined 1 month later. At 9 months, the geometric mean concentrations (GMCs) were significantly higher for all vaccine serotypes in vaccinated children compared with controls (means varied from 0.49 microg/ml for serotype 4 to 2.37 microg/ml for serotype 14). At 18 months, antibody concentrations remained significantly higher in vaccinated children (means varied from 0.19 microg/ml for serotype 4 to 1.1 microg/ml for serotype 14). In children who had received conjugate vaccine in infancy, the conjugate vaccine at 18 months produced a significant booster response for serotypes 1, 6B, 14, 19F, and 23F (means varied from 2.74 microg/ml for serotype 19F to 15.52 microg/ml for serotype 6B) and produced a comparable response to a first dose of conjugate at this age for serotypes 4, 5, 9V, and 18C. Boosting at 18 months with polysaccharide vaccine produced higher antibody concentrations to all serotypes in children who had previously received conjugate vaccine compared to children who had not received the conjugate vaccine in infancy. In conclusion, the 9-valent pneumococcal conjugate vaccine given in infancy elicits significant and long-lasting antibody responses which can be boosted with either the conjugate or polysaccharide vaccines.     

Safety and immunogenicity of a live-attenuated influenza vaccine blended and filled at two manufacturing facilities

This study was designed to compare the safety and immunogenicity of a trivalent live-attenuated, cold-adapted influenza vaccine (CAIV-T) blended and filled at two different manufacturing facilities (Medeva and Aviron-PA). The vaccines contained approximately 10(7) TCID(50) (median tissue culture infectious dose) of each of the three recommended 1997-1998 influenza vaccine components, A/Shenzhen/227/95 (H1N1) (A/Bayern/7/95 (H1N1)-like strain), A/Wuhan/359/95 (H3N2), and B/Ann Arbor/1/94 (B/Beijing/184/93-like strain). Two hundred and twenty-five healthy Australian children aged 12-42 months were enrolled and randomized in a 3:2 ratio to receive CAIV-T blended and filled either at Medeva or at Aviron-PA. Two doses of CAIV-T were given 4-6 weeks apart as an intranasal spray. Three blood specimens were collected (immediately before doses one and two, and 28 +/- 5 days following dose two) for measuring hemagglutination inhibition (HAI) antibody responses. Adverse events occurring within 10 days and serious adverse events occurring within 42 days were collected. Serum HAI antibody levels were measured against the three vaccine strains. Equivalent immunogenicity between the two vaccine groups was pre-specified as: (1) within 20% difference in seroconversion rates (HAI titers > or =4-fold rise); and (2) within 4-fold difference in the 90% confidence interval of geometric mean titer ratio. Among 10 pre-specified adverse events, only vomiting had significantly different incidence rates in the two vaccine groups following dose one (3% versus 13%, P = 0.01) but the difference disappeared following dose two (4% versus 4%). Differences in seroconversion rates following dose two between the two vaccine groups in pre-vaccination seronegative children were all <20% for the three vaccine strains (16% for H1N1, 0% for H3N2, and 0% for B). The results indicate that CAIV-T blended and filled in the two facilities had equivalent profiles of safety and immunogenicity.     

Persistence of rabies antibody 5 years after pre-exposure prophylaxis with human diploid cell antirabies vaccine and antibody response to a single booster dose

In 1978, 22 staff members of the National Institute of Virology, Pune, India, were given two doses of human diploid cell antirabies vaccine (HDCV) for primary pre-exposure prophylactic immunization; the interval between the two doses being approximately 4 weeks. Eighteen of these 22 vaccinees were given a booster dose 1 year later. All 18 vaccinees developed protective levels of antibody; most of them had antibody levels exceeding 10 IU/ml. In 1984, 5 years after the booster dose, 11 (79.0%) of 14 vaccinees tested still possessed neutralizing antibody levels ranging from 0.5 IU/ml to 10 IU/ml. Fourteen days after the administration of a booster dose, the antibody levels ranged from 10 to greater than or equal to 100 IU/ml for all except one vaccine (5.2 IU/ml). These findings demonstrate that the majority of vaccines retained detectable neutralizing antibody after pre-exposure prophylaxis for as long as 5 years and that a single booster dose thereafter evoked a good antibody response.     

Immunogenicity and safety of a liquid Pentavalent (DTwP-Hb-Hib) combination vaccine manufactured by Human Biologicals Institute in 6–8 weeks old healthy infants: A phase III,randomized, single blind,non-inferiority study

BackgroundA liquid Pentavalent (DTwP-Hb-Hib) combination vaccine, developed by Human Biologicals Institute, underwent a Phase III clinical study in India. In this randomized, single blind, non-inferiority study, the immunogenicity and safety of this Investigational vaccine was compared with Pentavac SD® vaccine in 6–8 weeks old healthy infants.MethodsA total of 405 healthy infants aged 6–8 weeks old were randomized in 2:1 ratio to receive three doses of either the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine or Pentavac SD® vaccine at four to six weeks interval. Immunogenicity was compared by estimation of antibody titers before the first dose and 4–6 weeks after the third dose of vaccination. Safety of each vaccine was assessed and compared by collection of data on solicited and unsolicited adverse events throughout the study period.ResultsOut of a total of 405 enrolled subjects, 387 subjects completed the study. The seroconversion rates, seroprotection rates and geometric mean titres of the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine group were found to be comparable and non-inferior to the Pentavac SD® vaccine group at 4–6 weeks after the third dose of vaccination. Pain, erythema and swelling at the site of injection were found to be the most common local adverse events whereas fever, irritability and unusual crying were found to be the most common systemic adverse events in both the vaccine groups. No vaccine related serious adverse event was reported. In this study, both the Investigational vaccine as well as the Comparator vaccine were found to be immunogenic and well tolerated.ConclusionAfter assessment of the results of the study it was concluded that the Investigational liquid Pentavalent (DTwP-Hb-Hib) combination vaccine developed by Human Biologicals Institute was immunogenic and safe when administered to infants aged 6–8 weeks and was non-inferior in immunogenicity and safety to Pentavac SD® vaccine.Clinical Trial Registry of India Identifier: CTRI/2016/01/006541.     

A murine model for the study of immune memory in response to pneumococcal conjugate vaccination

We developed a murine model for assessment of immunological memory and antibody-induced protection to nasopharyngeal (NP) challenges. BALB/c female mice (n = 10 mice per study parameter) were immunized with two priming doses of the licensed 7-valent pneumococcal (Pnc) conjugate vaccine and immune responses [antibody immunoglobulin G (IgG) levels, avidity and opsonophagocytic activity] were monitored for 26 weeks until IgG levels decreased to nearly baseline. A booster dose of either 2 microg conjugate or 5 microg polysaccharide vaccine was given at week 26. The ability of these two treatments to recall immune memory established by the conjugate vaccine was determined for types 4 and 14 for up to 63 days post-booster. The ability of challenge with pneumococcal type 14 to recall the immune response was also evaluated, as well as, the number of antibody secreting cells (ASC) specific to polysaccharide (Ps) 4, 6B, and 14. A higher dose of conjugate vaccine (2 microg) was necessary to elicit a significant increase in IgG levels after priming with one dose. Priming with lower doses (0.5 and 1.0 microg) only elicited modest increases in IgG levels. Recall of the immune response was found with either conjugate or Ps vaccines. NP challenge with type 14 at week 26 did not recall the immune response, although reduction in NP Pnc load was seen post-primary immunization at 5, 10 and 26 weeks. ASCs were detected in response to either conjugate or Ps booster doses. This model allows for the screening and determination of potential alternative vaccination regimens and the study of immunological markers of memory following Pnc vaccination.     

Immunity to avian pneumovirus infection in turkeys following in ovo vaccination with an attenuated vaccine

Fertile turkey eggs after 24 days of incubation were vaccinated in ovo with a commercial live attenuated subtype A avian pneumovirus (APV) vaccine. Hatchability was not adversely affected. When a high dose (10 times maximum commercial dose) of vaccine was tested in maternal antibody negative (MA-) eggs, mild clinical signs developed in a small proportion of the poults for 1-4 days only. Post-vaccination antibody titres at 3 weeks of age were significantly higher than those seen when the same dose was administered by eyedrop or spray at day-old. A low dose (end of shelf-life titre) of vaccine given to MA- eggs did not cause disease and vaccinated poults were 100% protected against virulent APV challenge at 3 or 5 weeks of age. Post-vaccination antibody titres reached significant levels at 3 weeks of age, whereas those from MA- poults vaccinated by spray at day-old with a similar low dose did not. In a 'worst-case' scenario, maternal antibody positive (MA+) poults vaccinated in ovo with the low dose were still 77% protected against clinical disease, despite lack of seroconversion. The recommended commercial dose of vaccine given to MA- eggs in ovo induced 100% protection against virulent APV challenge for up to 14 weeks of age, even though post-vaccination antibody titres had dropped to insignificant levels at this age. In ovo vaccination with a mixture of the recommended commercial doses of live APV and Newcastle disease (ND) vaccines had no detrimental affect on the efficacy of the APV vaccine. This is the first report of the successful use of an APV vaccine being given in ovo. The results indicate that for turkeys, in ovo vaccination with a live attenuated APV vaccine is safe and effective against virulent challenge and comparable with vaccination by conventional methods.     

Safety and immunogenicity of sequential pneumococcal immunization in preschool asthmatics

Objective

Respiratory infections are major triggers of exacerbations in preschool asthma. Many countries’ guidelines recommend immunization against pneumococci for patients suffering from chronic airway disease. Beyond infancy, however, data on the immunogenicity and safety are scarce. Also, the interval between priming and booster is a matter of debate.

Patients and Methods

Seventy preschool asthmatics (2–5-year-old; mild to moderate asthma) underwent sequential immunization: one dose of seven-valent pneumococcal conjugate vaccine (PCV-7) followed by a single dose of 23-valent pneumococcal polysaccharide vaccine (PPV-23). We randomly assigned half of the vaccinees to receive PPV-23 eight weeks after PCV-7 (group A), and the rest to a 10-month interval (group B). Pneumococcal antibody concentrations to serotype 4, 5, 6B, 7, 9V, 14, 18c, 19F and 23F were determined initially, after two and 12 months after PCV-7. Local and systemic reactions to each vaccine were recorded.

Results

Initially, depending on the serotype, up to 79.4% (group A) or 80.4% (group B) individuals did not reach the protective antibody threshold of 0.35 μg/ml. Sequential pneumococcal immunization was immunogenic in preschool asthmatics, inducing protection in the majority of our children. Subjects boostered after eight weeks had significantly lower antibody levels than those boostered after 10 months. Local and systemic adverse events were mild in character and self-limiting.

Conclusions

Although both sequential pneumococcal vaccine regimens were safe and immunogenic among preschool asthmatics, immunogenicity was higher when the booster was given after 10 months.     

肾综合征出血热疫苗免疫后血清学监测

目的 监测肾综合征出血热(HFRS)疫苗免疫接种人群血清抗体水平变化并评价疫苗血清学效果。方法 以村为单位,16～60岁健康者(删除既往患HFRS者、外出>9个月及疫苗禁忌症者)为观察对象,按接种和对照各半的原则随机分组,接种组共10 460人,对照组16 159人。采用间接免疫荧光法测特异性IgG荧光抗体,用微量细胞病变中和试验测中和抗体。结果 接种前血清抗体阴性者全程接种后2周荧光抗体阳转率为100.0％(67/67,95％CI:96.3～100.0),中和抗体阳转率为44 4％(8/18,95％CI:22.0～69.0),几何平均滴度分别为72.1和4.6。1年后进行加强免疫,加强免疫前、免疫后2周,免疫后1年、1.5年、2年、3年和5年,荧光抗体阳性率分别为28.6％、83.3％、75.0％、53.1％、22.6％、10.0％、55.0％;中和抗体阳性率分别为14.8％、55.6％、35.0％、31.3％、26.0％、10.0％、50.0％。免疫(感染)增强反应需要进一步研究。结论 HFRS疫苗免疫效果良好,血清抗体持续时间较长。     

Patterns of antibody response in humans to the anthrax vaccine adsorbed (AVA) primary (six-dose) series

The antibody profile during and after the six-dose primary vaccination series with anthrax vaccine adsorbed (AVA, Biothrax) was characterized in 86 human volunteers. Ninety-three percent of recipients developed IgG antibodies to Bacillus anthracis protective antigen (PA) after two doses, and 100% were seropositive after dose #3. Geometric mean concentrations (GMC) of IgG to PA measured before and after each dose were significantly lower after injection #3 (peak GMC=146.65 microg/mL, trough GMC=15.16 microg/mL) than after injections #4 (peak GMC=430.46 microg/mL, trough GMC=94.57 microg/mL), #5 (peak GMC=415.05 microg/mL, trough GMC=81.94 microg/mL), or #6 (peak GMC=401.16 microg/mL, trough GMC=96.19 microg/mL) (por=0.7923 for each). Decay rates for IgG to PA were significantly faster after injection #3 (half life [T1/2]=39.21 days) than after injections #4 (T1/2=72.03 days), #5 (T1/2=70.14 days), and #6 (T1/2=74.59 days) (p相似文献   

Immunisation schedules for non-replicating nasal vaccines can be made simple by allowing time for development of immunological memory

Mice immunised intranasally with multiple doses of outer membrane vesicles (OMVs) from group B meningococci developed antibody responses that depended on the interval between doses. High levels of antibodies in saliva and extracts of faeces were induced within 4 weeks after an OMV vaccine had been given at weekly intervals, whereas the antibody responses in these samples were negligible when given four times at 1-day or 1-h intervals, or as one large dose. Only modest responses were obtained in serum after 4 weeks, however, whether the vaccine had been given repeatedly at any schedule, including the 1-week interval, or as one dose. On the other hand, two large doses given 8 weeks apart induced booster antibody responses in both serum and secretions that matched the responses from a second series of the four smaller doses. Intranasal immunisations may thus stimulate immunological memory more rapidly in secretions than in serum. In order to secure adequate systemic responses by a minimum of doses, nasal vaccines should therefore be given at intervals longer than 4 weeks, in harmony with the intervals recommended for injectable vaccines.     

Dose response of CRM197 and tetanus toxoid-conjugated Haemophilus influenzae type b vaccines

High vaccine cost has limited use of conjugate vaccines in the developing world where the disease burden is greatest. Fixed fractional doses of Haemophilus influenzae type b (Hib) vaccines have been shown to be immunogenic, but dose responses of these vaccines in humans are needed to determine the lowest immunogenic dose as an option for lowering vaccine cost. We randomized children to receive one of five doses (0.625, 1.25, 2.5, 5.0 and 10 microg) of either a diphtheria CRM197 or tetanus toxoid-conjugated Hib vaccine. The children received a primary three-dose series at 6, 10, and 14 weeks of age and a booster dose at 9 months. Anti-PRP IgG antibodies were measured at each vaccination, at 18 weeks, and at one week following the booster dose. Concentrations of > or =1.25 microg of HibCRM197 vaccine produced mean anti-PRP responses at 18 weeks of > or =5.72 microg/ml and > or =0.15 microg/ml was achieved in >98% of the children with at least 79% reaching anti-PRP concentrations of > or =1.0 microg/ml. Concentrations of > or =1.25 microg of Hib-tetanus vaccine produced mean anti-PRP responses at 18 weeks of > or =8.63 microg/ml and > or =0.15 microg/ml was achieved in 100% of the children with at least 88.9% reaching anti-PRP concentrations of > or =1.0 microg/ml. While mean antibody concentrations after either vaccine decreased over time, the proportion of children with antibody levels of > or =0.15 microg/ml had not changed significantly at the 9 month measurement. Immunologic memory was demonstrated by significant increases in mean antibody concentrations one week after the booster dose for doses > or =1.25 microg of HibCRM197 and Hib-tetanus to mean concentrations > or =37.71 and 16.07 microg/ml, respectively. There were no differences in antibody responses for vaccine doses > or =1.25 microg of the same vaccine or between the same concentrations of the two different vaccines. Our data suggest that doses of these vaccines of > or =1.25 microg may be sufficient to stimulate an immune response that offers both short and longer term protection from invasive Hib disease.     

Modelling the long-term persistence of neutralizing antibody in adults after one dose of live attenuated Japanese encephalitis chimeric virus vaccine

In a study conducted in a non-endemic area, a live attenuated Japanese encephalitis chimeric virus vaccine (JE-CV) was found to provide 97% seroprotection at 6 months in JE-naive adults after 1 dose, and 87% of those protected at 6 months were still protected at 5 years. Because long-term seroprotection data are essential for decision-making on the need and timing of boosters, we applied statistical models to this dataset to predict individuals' neutralizing antibody titres and seroprotection up to 25 years post-vaccination. Three types of statistical model (linear, piecewise linear and exponential-type) with fixed and random effects were constructed to model antibody decline from the observed peak in antibody levels measured 28 days after vaccination. Individual seroprotection was based on the accepted threshold of 1:10 dilution units (antibody titre ≥10). The piecewise linear mixed model provided best fit amongst all tested models and identified 2 periods of antibody decline: an initial period of rapid decline followed by a period of much slower decline (50 times) starting on average 3.2 months (5th to 95th percentile range: 1.4-7.3) after vaccination. Predicted median antibody titres at 10 years were 38 (<10-174) and the corresponding seroprotection rate was 85.5% (72.7-94.9). The estimated median duration of seroprotection was 21.4 years (5th to 95th percentile range: 7.3-34.0). This analysis suggests that one dose of JE-CV confers to most adults a high level of protection against Japanese encephalitis for at least 10 years.     

Immunogenicity, reactogenicity, and safety of a seven-valent pneumococcal conjugate vaccine (PCV7) concurrently administered with a fully liquid DTPa-IPV-HBV-Hib combination vaccine in healthy infants

AIM OF THE STUDY: To evaluate the immunogenicity, safety and reactogenicity of a seven-valent pneumococcal conjugate vaccine (PCV7) when given concomitantly with a fully liquid DTaP-IPV-HBV-Hib combination vaccine. METHODS: Two hundred and sixty-six healthy infants in France (n=136) and Germany (n=130) were randomized to receive DTaP-IPV-HBV-Hib and PCV7 (test group) at the age of 2, 3 and 4 months (primary series) and 12-15 months (booster dose), or to receive DTaP-IPV-HBV-Hib at the same time points but PCV7 at the ages of 5, 6, 7 and 13-16 months (control group). Antibody levels to all vaccine antigens were measured before dose 1, 1 month after dose 3, at the time of booster, and 1 month later. Safety data were collected after each vaccine dose. RESULTS: Two hundred and fifty-seven infants (test group, 131; control group, 126) completed the primary immunization series and two hundred and forty-five received the booster dose (test group, 125; control group, 120). Depending on the serotype, 92.8-100% of subjects in the test group achieved antibody levels >or=0.15 microg/mL for PCV7 antigens at 5 months of age, and 89.7-99.1% of them antibody levels >or=0.50 microg/mL 1 month after booster. For DTaP-IPV-HBV-Hib, there was no statistically significant difference between the two groups in the proportion of infants that achieved pre-defined seroprotective levels for each antigen at 5 months and 1 month after booster. Frequency of local and systemic reactions was similar in both groups except for fever above 38.0 degrees C, which was more frequent in the test group after dose 1, 2 or 4. Fever >39.0 degrees C was only reported from three children in each group. CONCLUSION: The PCV7 vaccine was highly immunogenic, well tolerated, and safe when coadministered with the DTPa-IPV-HBV-Hib vaccine at 2, 3, and 4 months of age and a booster dose at 12-15 months. In this study, PCV7 did not show any relevant influence on the immunogenicity and safety of the concurrently administered DTPa-IPV-HBV-Hib vaccine.     

Immunogenicity and safety of a combined DTaP-IPV vaccine compared with separate DTaP and IPV vaccines when administered as pre-school booster doses with a second dose of MMR vaccine to healthy children aged 4-6 years

Combination vaccines represent one solution to the problem of increased numbers of injections during single clinic visits. A combined DTaP-IPV (Infanrix-IPV) vaccine has been developed for use as a pre-school booster. Four hundred healthy children aged 4-6 years previously primed with 4 doses of DTaP vaccine (Infanrix), 3 doses of poliovirus vaccine and 1 dose of MMR vaccine were randomized to receive single doses of either the combined DTaP-IPV vaccine or separate DTaP and IPV vaccines in a Phase II trial (DTaP-IPV-047). All children also received a second dose of MMR vaccine. Immunogenicity was assessed in serum samples taken before and 1 month after booster administration. Safety was actively assessed for 42 days post-vaccination. Non-inferiority of the DTaP-IPV vaccine to separate DTaP and IPV vaccines was demonstrated for all DTaP antigen booster response rates and poliovirus geometric mean titers of antibody ratios. Post-vaccination, > or =99.4% of children in both groups had seroprotective levels of anti-diphtheria and anti-tetanus antibodies (> or =0.1IU/mL) and seroprotective anti-poliovirus antibody titers (> or =1:8). All children in both groups were seropositive for measles, mumps and rubella antibodies, with similar post-vaccination geometric mean concentrations/titers. No significant differences were observed in the incidence of solicited local or general symptoms, unsolicited symptoms and serious adverse events between the two groups. This combined DTaP-IPV appeared safe and immunogenic when given as a booster dose at 4-6 years of age. The DTaP-IPV vaccine had no negative effect on the response to co-administered MMR vaccine, making it well-suited for use as a pre-school booster.