Antibody persistence and booster response of a quadrivalent meningococcal conjugate vaccine in adolescents.

OBJECTIVE: To evaluate the tolerability and immunogenicity of a booster dose of the quadrivalent meningococcal conjugate vaccine MenACWY-CRM (Menveo, Novartis Vaccines and Diagnostics, Siena, Italy) administered 3 years after primary vaccination of adolescents enrolled in a phase 3 study with either MenACWY-CRM or MenACWY-D (Menactra, Sanofi Pasteur, Swiftwater, Pennsylvania). STUDY DESIGN: A total of 730 healthy adolescents participated, including 622 initial study participants who received primary vaccination with MenACWY-CRM (n = 367) or MenACWY-D (n = 255) 3 years previously and 108 age-matched vaccine-naïve controls. A subset of MenACWY-CRM (n = 83) and MenACWY-D (n = 77) recipients were administered a MenACWY-CRM booster dose 3 years postprimary vaccination. Immunogenicity prior to and after the booster dose of MenACWY-CRM was measured by serum bactericidal assay with human complement (hSBA). Local and systemic reactions and adverse events were monitored in subjects receiving the booster dose. RESULTS: At 3 years postprimary vaccination, 64%, 82%, and 65% of subjects initially vaccinated with MenACWY-CRM (n = 367) showed hSBA titers ≥8 against serogroups C, W-135, and Y, respectively; this was lower for serogroup A (28%). Significantly more MenACWY-CRM recipients had hSBA titers ≥8 for serogroups W-135 and Y than MenACWY-D recipients (n = 255). A MenACWY-CRM booster dose resulted in 99%-100% of subjects demonstrating hSBA titers ≥8 against all serogroups, irrespective of primary vaccination (MenACWY-CRM, n = 83; MenACWY-D, n = 77). The booster dose was well tolerated without significant adverse events. CONCLUSIONS: MenACWY-CRM can be used to boost adolescents who have received a primary vaccination with either MenACWY-CRM or MenACWY-D.

Clinical efficacy of cell culture­derived and egg­derived inactivated subunit influenza vaccines in healthy adults.

BACKGROUND: More efficient methods are needed to manufacture influenza vaccines. This trial compared the efficacy of cell culture-derived influenza vaccine (CCIV) and egg-derived trivalent inactivated vaccine (TIV) with placebo against laboratory-confirmed influenza illness in healthy adults in the United States, Finland, and Poland during the 2007-2008 influenza season. METHODS: A total of 11,404 study participants aged 18-49 years were randomized equally to receive CCIV (Optaflu; n = 3828), TIV (Agrippal; n = 3676), or placebo (n = 3900). Each participant was observed during a 6-month study surveillance period. Nasal and throat swabs for virus isolation and characterization were collected from all patients with influenza-like illness. Vaccine immunogenicity was evaluated in a subset of 1045 participants. RESULTS: Efficacy of CCIV and TIV against vaccine-like (83.8% [1-sided 97.5% confidence interval [CI] lower limit, 61.0%] and 78.4% [1-sided 97.5% CI lower limit, 52.1%], respectively) and all circulating influenza virus strains (69.5% [1-sided 97.5% CI lower limit, 55.0%] and 63.0% [1-sided 97.5% lower limit, 46.7%], respectively) exceeded the Center for Biologics Evaluation and Research efficacy criteria. Immunogenicity of both vaccines exceeded the Center for Biologics Evaluation and Research licensing criteria. Both vaccines were well tolerated, with similar safety profiles. Most solicited reactions were mild to moderate in severity and transient. No vaccination-related serious adverse events were reported; no withdrawals resulted from vaccine-related adverse events. CONCLUSIONS: Both CCIV and TIV were effective in preventing influenza caused by vaccine-like and by all circulating influenza virus strains, were well tolerated, and had good safety profiles. Both vaccines can be considered for annual influenza vaccination campaigns. CLINICAL TRIALS REGISTRATION: NCT00630331.

Quadrivalent Influenza Vaccine Prevents Illness and Reduces Healthcare Utilization Across Diverse Geographic Regions During Five Influenza Seasons: A Randomized Clinical Trial.

BACKGROUND: We evaluated an inactivated quadrivalent influenza vaccine (IIV4) in children 6-35 months of age in a phase III, observer-blind trial. METHODS: The aim of this analysis was to estimate vaccine efficacy (VE) in preventing laboratory-confirmed influenza in each of 5 independent seasonal cohorts (2011-2014), as well as vaccine impact on healthcare utilization in 3 study regions (Europe/Mediterranean, Asia-Pacific and Central America). Healthy children were randomized 1:1 to IIV4 or control vaccines. VE was estimated against influenza confirmed by reverse transcription polymerase chain reaction on nasal swabs. Cultured isolates were characterized as antigenically matched/mismatched to vaccine strains. RESULTS: The total vaccinated cohort included 12,018 children (N = 1777, 2526, 1564, 1501 and 4650 in cohorts 1-5, respectively). For reverse transcription polymerase chain reaction confirmed influenza of any severity (all strains combined), VE in cohorts 1-5 was 57.8%, 52.9%, 73.4%, 30.3% and 41.4%, respectively, with the lower limit of the 95% confidence interval >0 for all estimates. The proportion of vaccine match for all strains combined in each cohort was 0.9%, 79.3%, 72.5%, 24.1% and 28.6%, respectively. Antibiotic use associated with influenza illness was reduced with IIV4 by 71% in Europe, 36% in Asia Pacific and 59% in Central America. CONCLUSIONS: IIV4 prevented influenza in children 6-35 months of age in each of 5 separate influenza seasons in diverse geographical regions. A possible interaction between VE, degree of vaccine match and socioeconomic status was observed. The IIV4 attenuated the severity of breakthrough influenza illness and reduced healthcare utilization, particularly antibiotic use.

Clinical Presentation of Influenza in Children 6 to 35 Months of Age: Findings From a Randomized Clinical Trial of Inactivated Quadrivalent Influenza Vaccine.

BACKGROUND: In an exploratory analysis of an inactivated quadrivalent influenza vaccine (IIV4) trial in children 6-35 months without risk factors for influenza, we evaluated clinical presentation of influenza illness and vaccine impact on health outcomes. METHODS: This phase III trial was conducted in 13 geographically diverse countries across 5 influenza seasons (2011-2014). Children were randomized 1:1 to IIV4 or control. Active surveillance was performed for influenza-like episodes (ILE); influenza was confirmed by reverse transcription polymerase chain reaction (RT-PCR). The total vaccinated cohort was evaluated (N = 12,018). RESULTS: 5702 children experienced ≥1 ILE; 356 (IIV4 group) and 693 (control group) children had RT-PCR-confirmed influenza. Prevalence of ILE was similar in RT-PCR-positive and RT-PCR-negative cases regardless of vaccination. Breakthrough influenza illness was attenuated in children vaccinated with IIV4; moderate-to-severe illness was 41% less likely to be reported in the IIV4 group than the control group [crude odds ratio: 0.59 (95% confidence intervals: 0.44-0.77)]. Furthermore, fever >39°C was 46% less frequent following vaccination with IIV4 than with control [crude odds ratio: 0.54 (95% confidence intervals: 0.39-0.75)] in children with breakthrough illness. Health outcome analysis showed that, each year, IIV4 would prevent 54 influenza cases per 1000 children and 19 children would need to be vaccinated to prevent 1 new influenza case. CONCLUSIONS: In addition to preventing influenza in 50% of participants, IIV4 attenuated illness severity and disease burden in children who had a breakthrough influenza episode despite vaccination.

Phase 4, Post-Marketing Safety Surveillance of the MF59-Adjuvanted Influenza Vaccines FLUAD® and VANTAFLU® in South Korean Subjects Aged ≥65 Years.

BACKGROUD: Influenza vaccination is recommended for adults aged ≥65 years as they are at high risk of significant morbidity and mortality. This open-label, multicenter, post-marketing surveillance study assessed the safety of the MF59-adjuvanted trivalent inactivated subunit influenza vaccine, which is marketed as FLUAD® and VANTAFLU®, in South Korean subjects aged ≥65 years. MATERIALS AND METHODS: Solicited local and systemic adverse events (AEs) were collected from day 1 to 4 of the study. All unsolicited AEs and serious AEs (SAEs) were recorded from day 1 until study termination (day 29). RESULTS: Of the 770 subjects enrolled (FLUAD®, n = 389; VANTAFLU®, n = 381), 39% overall experienced any solicited AE. Local AEs were reported by 33% of subjects overall; with the most common events being injection-site pain (30%) and tenderness (27%). Systemic AEs were reported by 19% of subjects overall with the most common events being myalgia (11%) and fatigue (8%). CONCLUSION: These results show that the MF59-adjuvanted influenza vaccine known as FLUAD® or VANTAFLU® had acceptable safety profiles in older adults (aged ≥65 years) in South Korea.

Prevention of vaccine-matched and mismatched influenza in children aged 6-35 months: a multinational randomised trial across five influenza seasons.

BACKGROUND: Despite the importance of vaccinating children younger than 5 years, few studies evaluating vaccine prevention of influenza have been reported in this age group. We evaluated efficacy of an inactivated quadrivalent influenza vaccine (IIV4) in children aged 6-35 months. METHODS: In this phase 3, observer-blinded, multinational trial, healthy children from 13 countries in Europe, Central America, and Asia were recruited in five independent cohorts, each in a different influenza season. Participants were randomly assigned (1:1) to either IIV4 (15 µg haemagglutinin antigen per strain per 0·5 mL dose; a single dose on day 0 for vaccine-primed children, and two doses, on days 0 and 28, for vaccine-unprimed children) or to one or two doses of a non-influenza control vaccine. Primary endpoints were moderate-to-severe influenza or all influenza (irrespective of disease severity) confirmed by RT-PCR on nasal swabs. Cultured isolates were further characterised as antigenically matched or mismatched to vaccine strains. Efficacy was assessed in the per-protocol cohort and total vaccinated cohort (time-to-event analysis), and safety was assessed in the total vaccinated cohort. FINDINGS: Between Oct 1, 2011, and Dec 31, 2014, 12 018 children were recruited into the total vaccinated cohort (6006 children in the IIV4 group and 6012 children in the control group). 356 (6%) children in the IIV4 group and 693 (12%) children in the control group had at least one case of RT-PCR-confirmed influenza. Of these 1049 influenza strains, 138 (13%) were A/H1N1, 529 (50%) were A/H3N2, 69 (7%) were B/Victoria, and 316 (30%) were B/Yamagata. Overall, 539 (64%) of 848 antigenically characterised isolates were vaccine-mismatched (16 [15%] of 105 for A/H1N1; 368 [97%] of 378 for A/H3N2; 54 [86%] of 63 for B/Victoria; 101 [33%] of 302 for B/Yamagata). Vaccine efficacy was 63% (97·5% CI 52-72) against moderate-to-severe influenza and 50% (42-57) against all influenza in the per-protocol cohort, and 64% (53-73) against moderate-to-severe influenza and 50% (42-57) against all influenza in the total vaccinated cohort. There were no clinically meaningful safety differences between IIV4 and control. INTERPRETATION: IIV4 prevented influenza A and B in children aged 6-35 months despite high levels of vaccine mismatch. Vaccine efficacy was highest against moderate-to-severe disease, which is the most clinically important endpoint associated with greatest burden. FUNDING: GlaxoSmithKline Biologicals SA.

The relationship between condom use and herpes simplex virus acquisition.

BACKGROUND: Few studies have evaluated the relationship between condom use and herpes simplex virus type 2 (HSV-2) and HSV type 1 (HSV-1) acquisition. OBJECTIVE: To assess the relationship between condom use and acquisition of HSV-2 and HSV-1 among men and women. DESIGN: Analysis of data collected as part of a clinical trial of an ineffective candidate vaccine for HSV-2. SETTING: Sexually transmitted disease clinics. PARTICIPANTS: Men and women at risk for HSV-2 acquisition, defined as having 4 or more sexual partners or having a sexually transmitted disease in the past year. MEASUREMENT: Acquisition of HSV-2 and HSV-1 as measured by viral culture or change to positive HSV serostatus. RESULTS: Of 1843 participants, 118 (6.4%) became infected with HSV-2. In multivariate analyses, participants reporting more frequent use of condoms were at lower risk for acquiring HSV-2 than participants who used condoms less frequently (hazard ratio, 0.74 [95% CI, 0.59 to 0.95]); categories of increasing condom use were 0% to 25%, 25% to 75%, and greater than 75% of sexual acts. Nineteen (2.9%) of 659 participants at risk for infection with HSV-1 became infected. No statistically significant association between condom use and infection with HSV-1 was found (hazard ratio, 0.79 [CI, 0.48 to 1.31]). LIMITATIONS: Use of condoms was measured by self-report, and persons who used condoms may have differed from those who did not. CONCLUSIONS: Consistent use of condoms is associated with lower rates of infection with HSV-2 and should be routinely recommended.

Five year follow-up after primary vaccination against tick-borne encephalitis in children.

BACKGROUND: A first tick-borne encephalitis (TBE) vaccine booster in children is currently suggested 3 years after completing either a conventional (doses on Days 0, 28 and 300) or accelerated conventional (doses on Days 0, 14 and 300) TBE immunization schedule. This recommendation, however, may not be appropriate in cases where different TBE vaccines have been used interchangeably during the primary immunization series. METHODS: To provide robust data to better inform such recommendations, TBE antibody persistence was evaluated after 3-5 years in four groups of children (aged 5-15 years): two groups previously primed with three doses of Encepur(®) Children (conventional/accelerated conventional schedule); and two groups previously primed with two doses of FSME-IMMUN(®) followed by a third dose of Encepur(®) Children (conventional/accelerated conventional schedule). Immunogenicity was evaluated using neutralization (NT) assays based on both vaccine antigens as well as on the Enzyme Linked Immunosorbent Assay (ELISA). RESULTS: In the two Encepur(®) Children groups (full series), protective NT titers of ≥10 were detected in 98-100% of children up to 5 years after their last primary vaccination, irrespective of schedule. In contrast, only 65-70% subjects in the FSME-IMMUN(®) Junior groups (mixed series) displayed NT titers ≥10 after 3 years. Thus, due to lower probability of achieving/maintaining long-term protective antibody levels (recently defined by the World Health Organization as an NT titer ≥10) after this time point, both FSME-IMMUN Junior groups were discontinued. CONCLUSION: A strong antibody response persists for at least 5 years after full primary vaccination with Encepur(®) Children. The study thus provides support for extending the time interval for a first booster dose after primary vaccination (conventional/accelerated conventional schedule) with Encepur(®) Children from 3 to 5 years.

Bioequivalence of Two Recombinant Human Growth Hormones in Healthy Male Volunteers after Subcutaneous Administration.

The bioequivalence of recombinant human growth hormone (rhGH) (somatropin) and its N-methionyl variant (Met-hGH) [Protropin((R)) (somatrem for injection)] was determined in 42 healthy male volunteers (n = 21 per treatment) who were randomized to receive either protein by subcutaneous administration of 0.1 mg kg(minus sign1). Serum samples were collected over 24 h after the injection, and the concentration of human growth hormone (hGH) were determined by an immunoradiometric assay. Bioequivalence of the two proteins was assessed by determining whether the 90% confidence limits for the ratio of geometric means using logarithmically transformed AUC and C(max) parameters (log(10)AUC(0--24), log(10)AUC(0--infty infinity), and log(10)C(max)) were within the 80--125% range. The bioequivalence of the two treatments was also tested by calculating a bioequivalance index (xi(2)) that measured the difference between the two mean concentration-time profiles. The 90% confidence intervals for the ratios of the geometric means for AUC were within the prescribed 80--125% range for bioequivalence. The upper limit of the 90% confidence interval for the ratio of the geometric means for C(max) fell slightly outside the 125% criterion even though the geometric mean itself, 106.6%, was very close to the ideal of 100%. There was a larger standard error associated with C(max) than with the AUCs, and this marginally larger confidence limit for C(max) resulted more from the variance among the subject than to the difference in the means. In fact, the bioequivalence index, xi(2), was 0.075, indicating that the mean curves after rhGH and Met-hGH are essentially superimposable.

Safety of a quadrivalent meningococcal serogroups A, C, W and Y conjugate vaccine (MenACWY-CRM) administered with routine infant vaccinations: results of an open-label, randomized, phase 3b controlled study in healthy infants.

BACKGROUND: The highest risk for invasive meningococcal disease (IMD) is in infants aged <1 year. Quadrivalent meningococcal conjugate vaccination has the potential to prevent IMD caused by serogroups A, C, W and Y. This phase 3b, multinational, open-label, randomized, parallel-group, multicenter study evaluated the safety of a 4-dose series of MenACWY-CRM, a quadrivalent meningococcal conjugate vaccine, concomitantly administered with routine vaccinations to healthy infants. METHODS: Two-month-old infants were randomized 3:1 to receive MenACWY-CRM with routine vaccines or routine vaccines alone at ages 2, 4, 6 and 12 months. Adverse events (AEs) that were medically attended and serious adverse events (SAEs) were collected from all subjects from enrollment through 18 months of age. In a subset, detailed safety data (local and systemic solicited reactions and all AEs) were collected for 7 days post vaccination. The primary objective was a non-inferiority comparison of the percentages of subjects with ≥1 severe systemic reaction during Days 1-7 after any vaccination of MenACWY-CRM plus routine vaccinations versus routine vaccinations alone (criterion: upper limit of 95% confidence interval [CI] of group difference <6%). RESULTS: A total of 7744 subjects were randomized with 1898 in the detailed safety arm. The percentage of subjects with severe systemic reactions was 16% after MenACWY-CRM plus routine vaccines and 13% after routine vaccines alone (group difference 3.0% (95% CI -0.8, 6.4%). Although the non-inferiority criterion was not met, post hoc analysis controlling for significant center and group-by-center differences revealed that MenACWY-CRM plus routine vaccinations was non-inferior to routine vaccinations alone (group difference -0.1% [95% CI -4.9%, 4.7%]). Rates of solicited AEs, medically attended AEs, and SAEs were similar across groups. CONCLUSION: In a large multinational safety study, a 4-dose series of MenACWY-CRM concomitantly administered with routine vaccines was clinically acceptable with a similar safety profile to routine vaccines given alone.

Antibody persistence and response to a booster dose of a quadrivalent conjugate vaccine for meningococcal disease in adolescents.

BACKGROUND: In a previous randomized phase 2 study in adolescents, a CRM197 meningococcal conjugate vaccine against serogroups A, C, W-135 and Y (MenACWY-CRM) was well tolerated and immunogenic, compared with a plain polysaccharide vaccine (MenACWY-PS). METHODS: This extension study assessed antibody persistence 5 years after primary vaccination with MenACWY-CRM (n = 50) or MenACWY-PS (n = 51), and the immunogenicity and reactogenicity of a dose of MenACWY-CRM given 5 years after primary vaccination; antibody response was also compared with vaccine-naive controls (n = 54). The primary endpoints were the percentage of subjects with titers ≥8 by serum bactericidal activity assay using human complement (hSBA) 5 years after primary vaccination and hSBA geometric mean titers 1 month after the MenACWY-CRM dose given in the current study. RESULTS: Five years after primary vaccination, over 70% of subjects who had received MenACWY-CRM were seropositive (hSBA titers ≥8) for serogroups C, W-135 and Y; for serogroups C and Y, the percentages of seropositive subjects were significantly higher in subjects previously vaccinated with MenACWY-CRM than in subjects previously vaccinated with MenACWY-PS. The MenACWY-CRM dose given 5 years postprimary vaccination elicited an anamnestic response across serogroups in those previously vaccinated with MenACWY-CRM. Responses in those previously vaccinated with MenACWY-PS were less robust but adequate and similar to that seen in the vaccine-naive group, both in magnitude and kinetics. MenACWY-CRM was well tolerated in all 3 groups. CONCLUSION: MenACWY-CRM provided a broad and persistent immune response in adolescents. A subsequent dose of MenACWY-CRM elicited an adequate antibody response, regardless of vaccine history.

Safety assessment and immunogenicity of a cell-culture-derived influenza vaccine in adults and elderly subjects over three successive influenza seasons.

BACKGROUND: Adult and elderly subjects previously immunized with cell culture-derived (CCIV; Optaflu(®)) or egg-derived (TIV; Agrippal(®)) trivalent influenza vaccines were enrolled in two extension studies (E1 and E2) to evaluate safety and immunogenicity after revaccination with CCIV/TIV alone or in combination with concomitant pneumococcal vaccine (PV). METHODS: Adults and elderly subjects (n = 2609) were randomized 1:1 in E1 and allocated 3:1 in E2 to receive CCIV/TIV. In E2, a subset of elderly subjects was randomized to receive CCIV/TIV, with or without PV. Adverse reactions were monitored for six months and immunogenicity was assessed by hemagglutination inhibition (HI) assay using CHMP criteria. RESULTS: Overall, the safety profile of both vaccines was similar, no serious adverse events related to either vaccine occurred. Mild or moderate pain was the most commonly reported reaction. Reactogenicity was slightly higher in elderly subjects receiving CCIV/TIV concomitantly with PV [46% vs. 37%; p = non-significant (NS)]. Both vaccines met CHMP licensure criteria for adults and elderly subjects. With concomitant CCIV and PV, all three CHMP criteria were met for A/H1N1 and A/H3N2, whereas the B strain only met seroprotection and GMR criteria. CONCLUSIONS: Safety and immunogenicity of CCIV was not influenced by the type of vaccine received previously or by concomitant PV administration.

Immunogenicity, safety and reactogenicity of a mammalian cell-culture-derived influenza vaccine in healthy children and adolescents three to seventeen years of age.

BACKGROUND: The safety and immunogenicity of the cell-culture-derived seasonal trivalent influenza vaccine ([CCIV]; Optaflu) has been reported previously in adults and the elderly. In this study, we compared the safety, reactogenicity and immunogenicity of CCIV with a conventional egg-derived trivalent influenza vaccine (TIV) in a healthy pediatric population. METHODS: A total of 3604 subjects were randomized to receive 2 doses of CCIV or TIV (3-8 years, n = 2630) at a 28-day interval or a single vaccination (9-17 years, n = 974). Antibody levels on days 1, 29 and 50 were measured by hemaglutination inhibition assay using egg-derived and cell-derived test antigens. Adverse reactions were solicited via memory aids for 7 days after each injection, and unsolicited adverse events/serious adverse events were collected for 6 months postvaccination. RESULTS: Noninferiority of CCIV versus TIV was demonstrated for most immunogenicity measures, particularly by using cell-derived antigen in the hemaglutination inhibition assay. In 3- to 8-year-olds (the primary objective), both CCIV and TIV met all 3 Committee for Medicinal Products for Human Use immunogenicity criteria for A/H1N1 and A/H3N2 strains. Lower immune responses were observed against the B strain, fulfilling Committee for Medicinal Products for Human Use criteria only for geometric mean ratio (TIV, CCIV) and seroconversion rate (TIV, CCIV [cell-derived antigen]). Both CCIV and TIV were safe and well tolerated, with no differences in local and systemic solicited reactions or in unsolicited adverse events/serious adverse events. CONCLUSION: CCIV produced in mammalian cell culture is a safe, well-tolerated and immunogenic alternative to conventional egg-derived influenza vaccines for children and adolescents.

Subunit influenza vaccines produced from cell culture or in embryonated chicken eggs: comparison of safety, reactogenicity, and immunogenicity.

BACKGROUND: This study assessed the safety, reactogenicity, and immunogenicity of an injectable cell culture-derived influenza vaccine (CCIV), compared with those of an injectable egg-based trivalent inactivated influenza vaccine (TIV). METHODS: Adult subjects (n = 613; 18 to <50 years of age) were randomized (1:1) to receive either CCIV or TIV. The safety and reactogenicity of the 2 vaccines were assessed on the basis of solicited indicators and other adverse events (AEs) within 7 days of vaccination. All serious AEs and those AEs resulting in withdrawal were recorded throughout the study. Antibody titers were determined by the hemagglutination inhibition assay, using egg- and cell-derived antigens. Immunogenicity was assessed on the basis of the ratio of postvaccination (day 22) geometric mean titers (GMTs) between the 2 vaccines, seroprotection rates, and seroconversion rates. RESULTS: There was no clinically relevant difference between the safety and reactogenicity profiles of the 2 vaccines. The immunogenicity of CCIV was demonstrated to be noninferior to that of TIV on the basis of the ratio of postvaccination GMTs between the 2 vaccines. GMTs, seroprotection rates, and seroconversion rates were comparable between the 2 vaccines. CONCLUSIONS: The safety, reactogenicity, and immunogenicity of the CCIV and the egg-based TIV are comparable.

Sample size for equivalence trials: a case study from a vaccine lot consistency trial.

For some trials, simple but subtle assumptions can have a profound impact on the size of the trial. A case in point is a vaccine lot consistency (or equivalence) trial. Standard sample size formulas used for designing lot consistency trials rely on only one component of variation, namely, the variation in antibody titers within lots. The other component, the variation in the means of titers between lots, is assumed to be equal to zero. In reality, some amount of variation between lots, however small, will be present even under the best manufacturing practices. Using data from a published lot consistency trial, we demonstrate that when the between-lot variation is only 0.5 per cent of the total variation, the increase in the sample size is nearly 300 per cent when compared with the size assuming that the lots are identical. The increase in the sample size is so pronounced that in order to maintain power one is led to consider a less stringent criterion for demonstration of lot consistency. The appropriate sample size formula that is a function of both components of variation is provided. We also discuss the increase in the sample size due to correlated comparisons arising from three pairs of lots as a function of the between-lot variance.

Simultaneous administration of meningococcal C conjugate vaccine and diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae type b conjugate vaccine in children: a randomized double-blind study.

BACKGROUND: Meningococcal C disease can be life-threatening in infants, young children and adolescents. New conjugate vaccines are immunogenic in young infants and induce immunologic memory, so we should consider incorporating them into the routine childhood immunization program. The objective of this study was to measure the safety and immunogenicity of a meningococcal C conjugate vaccine when given with routine childhood vaccines. METHODS: We carried out a randomized, double-blind, controlled clinical trial at children's hospitals in 3 Canadian cities. A convenience sample of 351 healthy 2-month-old infants was enrolled from the community and randomly allocated to receive either meningococcal C conjugate vaccine or the control (hepatitis B) vaccine. All participants received a concurrent injection of the combined diphtheria-tetanus-acellular pertussis-inactivated poliovirus-Haemophilus influenzae type b (DTaP-IPV-Hib) conjugate vaccine in the opposite limb. Participants were immunized at 2, 4, 6 and 15 months of age; adverse events were recorded after each dose. Serum bactericidal and ELISA meningococcal antibody levels in the participants were measured at 6, 7, 15 and 16 months of age; diphtheria, tetanus, H. influenzae type b, poliovirus and pertussis antibodies were measured at 7 months of age. A total of 323 (92%) participants completed all aspects of the study. The proportion of participants who suffered adverse events after each vaccine dose was the primary safety outcome. Geometric mean antibody titres and the proportion of participants with protective antibody levels after immunization were the primary immunologic outcomes. RESULTS: After 2 doses of the meningococcal C conjugate vaccine 99% of participants achieved a protective ( > or = 1:8) bactericidal meningococcal serogroup C antibody level, and after 3 doses this rate increased to 100%. Antibody levels to the concomitant vaccine antigens in the group receiving meningococcal C vaccine were similar to those in the control group except for higher antidiphtheria antibody titres (p < 0.001). Local injection site reactions (redness and induration) after the meningococcal conjugate vaccine were more frequent than after hepatitis B vaccine but less frequent than after the DTaP-IPV-Hib vaccine. CONCLUSIONS: The meningococcal C conjugate vaccine can be safely and effectively administered at the same visit as the other vaccine antigens routinely given to infants in Canada.