Developing the First Recombinant Factor XIII for Congenital Factor XIII Deficiency: Clinical Challenges and Successes.

Congenital factor XIII (FXIII) deficiency is a rare, autosomal recessive bleeding disorder with potentially life-threatening consequences. FXIII is composed of two subunits (A and B), and a deficiency or dysfunction of either can result in FXIII deficiency. Traditionally, FXIII deficiency has been managed by infusing plasma-derived products containing FXIII (fresh frozen plasma, cryoprecipitate, and plasma-derived FXIII concentrates), all of which contain both subunits. Despite the increased safety of plasma-derived products, concern remains regarding potential viral safety issues. This review describes the development, from concept to clinical use, of a recombinant FXIII molecule (containing subunit A only; rFXIII-A2) for congenital FXIII-A subunit deficiency. Unmet needs and ongoing challenges in congenital FXIII deficiency are also discussed. Despite the challenges in developing a product for a very rare bleeding disorder, the information gathered on efficacy, safety, and pharmacokinetics of FXIII replacement therapy represents the largest dataset on congenital FXIII-A subunit deficiency in the world. It also provides evidence for the safety and efficacy of monthly prophylaxis with 35 IU/kg of rFXIII-A2 in patients with FXIII-A subunit deficiency. The issues encountered and overcome, along with lessons learned, may be applied to and encourage the development of new recombinant products for other rare bleeding disorders.

Measles virus antibody responses in children randomly assigned to receive standard-titer edmonston-zagreb measles vaccine at 4.5 and 9 months of age, 9 months of age, or 9 and 18 months of age.

The World Health Organization recommends administration of measles vaccine (MV) at age 9 months in low-income countries. We tested the measles virus antibody response at 4.5, 9, 18, and 24 months of age for children randomly assigned to receive standard-titer Edmonston-Zagreb MV at 4.5 and 9 months, at 9 months, or at 9 and 18 months of age. At 4.5 months of age, 75% had nonprotective measles virus antibody levels. Following receipt of MV at 4.5 months of age, 77% (316/408) had protective antibody levels at 9 months of age; after a second dose at 9 months of age, 97% (326/337) had protective levels at 24 months of age. In addition, the response at both 9 and 24 months of age was inversely correlated with the antibody level at receipt of the first dose of MV, and the second dose of MV, received at 9 months of age, provided a significant boost in antibody level to children who had low antibody levels. In the group of 318 children who received MV at 9 months of age, with or without a second dose at 18 months of age, 99% (314) had protective levels at 24 months of age. The geometric mean titer at 24 months of age was significantly lower in the group that received MV at 4.5 and 9 months of age than in the group that received MV at 9 months of age (P = .0001). In conclusion, an early 2-dose MV schedule was associated with protective measles virus antibody levels at 24 months of age in nearly all children. Clinical Trials Registration. NCT00168558.

A randomized trial of a standard dose of Edmonston-Zagreb measles vaccine given at 4.5 months of age: effect on total hospital admissions.

Observational studies and trials from low-income countries indicate that measles vaccine has beneficial nonspecific effects, protecting against non-measles-related mortality. It is not known whether measles vaccine protects against hospital admissions. Between 2003 and 2007, 6417 children who had received the third dose of diphtheria, tetanus, and pertussis vaccine were randomly assigned to receive measles vaccine at 4.5 months or no measles vaccine; all children were offered measles vaccine at 9 months of age. Using hospital admission data from the national pediatric ward in Bissau, Guinea-Bissau, we compared admission rates between enrollment and the 9-month vaccination in Cox models, providing admission hazard rate ratios (HRRs) for measles vaccine versus no measles vaccine. All analyses were conducted stratified by sex and reception of neonatal vitamin A supplementation (NVAS). Before enrollment the 2 groups had similar admission rates. Following enrollment, the measles vaccine group had an admission HRR of 0.70 (95% confidence interval [CI], .52-.95), with a ratio of 0.53 (95% CI, .32-.86) for girls and 0.86 (95% CI, .58-1.26) for boys. For children who had not received NVAS, the admission HRR was 0.53 (95% CI, .34-.84), with an effect of 0.30 (95% CI, .13-.70) for girls and 0.73 (95% CI, .42-1.28) for boys (P = .08, interaction test). The reduction in admissions was separately significant for measles infection (admission HRR, 0 [95% CI, 0-.24]) and respiratory infections (admission HRR, 0.37 [95% CI, .16-.89]). Early measles vaccine may have major benefits for infant morbidity patterns and healthcare costs. Clinical trials registration NCT00168558.

Measles vaccination in the presence or absence of maternal measles antibody: impact on child survival.

BACKGROUND: Measles vaccine (MV) has a greater effect on child survival when administered in early infancy, when maternal antibody may still be present. METHODS: To test whether MV has a greater effect on overall survival if given in the presence of maternal measles antibody, we reanalyzed data from 2 previously published randomized trials of a 2-dose schedule with MV given at 4-6 months and at 9 months of age. In both trials antibody levels had been measured before early measles vaccination. RESULTS: In trial I (1993-1995), the mortality rate was 0.0 per 1000 person-years among children vaccinated with MV in the presence of maternal antibody and 32.3 per 1000 person-years without maternal antibody (mortality rate ratio [MRR], 0.0; 95% confidence interval [CI], 0-.52). In trial II (2003-2007), the mortality rate was 4.2 per 1000 person-years among children vaccinated in presence of maternal measles antibody and 14.5 per 1000 person-years without measles antibody (MRR, 0.29; 95% CI, .09-.91). Possible confounding factors did not explain the difference. In a combined analysis, children who had measles antibody detected when they received their first dose of MV at 4-6 months of age had lower mortality than children with no maternal antibody, the MRR being 0.22 (95% CI, .07-.64) between 4-6 months and 5 years. CONCLUSIONS: Child mortality in low-income countries may be reduced by vaccinating against measles in the presence of maternal antibody, using a 2-dose schedule with the first dose at 4-6 months (earlier than currently recommended) and a booster dose at 9-12 months of age. CLINICAL TRIALS REGISTRATION: NCT00168558.

Safety and effectiveness of recombinant factor XIII-A2 in congenital factor XIII deficiency: Real-world evidence.

BACKGROUND: Regular factor XIII (FXIII) prophylaxis is standard treatment for congenital FXIII A-subunit deficiency (FXIII-A CD). Recombinant factor XIII-A2 (rFXIII-A2) was extensively evaluated in the mentor trials. OBJECTIVE: To assess real-world safety and treatment effectiveness of rFXIII-A2 prophylaxis from the mentor 6 trial. PATIENTS/METHODS: mentor 6 was a noninterventional, postauthorization safety study investigating rFXIII-A2 prophylaxis in FXIII-A CD. rFXIII-A2 treatment was observed for 2 to 6 years per patient. The primary end point was documentation of adverse drug reactions (including anti-FXIII antibody development). Secondary end points were serious adverse events (SAEs), medical events of special interest (MESIs), and annualized bleeding rate (ABR). RESULTS: Among 30 patients (mean age, 25.5 years), there were 44 adverse events (AEs) (30 mild, 13 moderate, 1 severe). Eleven AEs were possibly/probably related to rFXIII-A2. Of four MESIs, two were unlikely related to rFXIII-A2 (accidental overdose, deep vein thrombosis), and two were possibly/probably related (nonneutralizing anti-FXIII antibody, decreased therapeutic response). All 10 SAEs were unlikely related to rFXIII-A2. Over a follow-up of 75.4 patient-years, there were six treatment-requiring bleeds (all trauma-related with no spontaneous bleeds), giving a treatment-requiring ABR of 0.066; five bleeds were treated successfully with rFXIII-A2. Eight of nine minor surgeries performed during rFXIII-A2 prophylaxis reported successful hemostatic outcomes (one missing evaluation). CONCLUSIONS: These data confirm that rFXIII-A2 prophylaxis is well tolerated as long-term care. There were no spontaneous bleeds, ABR was low, and rFXIII-A2 successfully treated bleeds in patients receiving rFXIII-A2 prophylaxis.

The effect of high-dose vitamin A supplementation at birth on measles incidence during the first 12 months of life in boys and girls: an unplanned study within a randomised trial.

Vitamin A treatment reduces mortality during acute measles infection, and vitamin A supplementation (VAS) to children above 6 months of age may reduce the incidence of measles infection. The effect of VAS at birth on measles incidence is unknown. In a randomised placebo-controlled trial in Guinea-Bissau, normal-birth-weight newborns were randomised to 50 000 IU (15 mg) VAS or placebo. During the trial, a measles epidemic occurred. We linked data from the trial with data from the measles infection surveillance and studied the effect of VAS on the measles incidence before 12 months of age in both sexes. A total of 165 measles cases were identified among the 4183 children followed from 28 d of age. Up to 6 months of age, the incidence rate ratio of measles for VAS compared with placebo was 0·54 (95 % CI 0·25, 1·15) among boys and 1·57 (95 % CI 0·80, 3·08) among girls (test of interaction, P = 0·04). The corresponding figures at 12 months were 0·67 (95 % CI 0·43, 1·05) and 1·17 (95 % CI 0·76, 1·79) (test of interaction, P = 0·08). VAS compared with placebo tended to be associated with less measles hospitalisation or death during the first 6 months of life in boys (P = 0·06), but not in girls. VAS at birth may affect the susceptibility to measles infection during the first 6 months of life in a sex-differential manner.

Nonacog beta pegol (N9-GP) in hemophilia B: First report on safety and efficacy in previously untreated and minimally treated patients.

BACKGROUND/OBJECTIVE: We report the first analysis of an extended half-life recombinant factor IX, nonacog beta pegol (N9-GP), in previously untreated patients (PUPs) and minimally treated patients with hemophilia B. METHODS: Paradigm 6 (Safety and Efficacy of Nonacog Beta Pegol [N9-GP] in Previously Untreated Patients With Haemophilia B) is a multicenter, open-label, single-arm, phase 3 trial. Main inclusion criteria were males aged < 6 years, with hemophilia B with factor IX (FIX) activity ≤ 2%, who were previously untreated or with ≤ 3 exposure days (EDs) to FIX-containing products. Patients received N9-GP 40 IU/kg once weekly (prophylaxis) or individualized dosing (preprophylaxis). Bleeds were treated with N9-GP 40 IU/kg (80 IU/kg if severe). The primary end point was incidence of anti-FIX inhibitory antibodies (inhibitors). Secondary end points included safety outcomes and annualized bleeding rate (ABR). RESULTS: At data cutoff (August 31, 2018), 38 patients had been screened, and 37 had received N9-GP (median age, 1.0 years [range, 0-4]). Total in-trial EDs amounted to 2833, representing ~ 65 patient-years. Two (6.1%) of 33 "at-risk" patients (patients with ≥ 10 EDs plus patients who developed inhibitors) developed high-titer inhibitors and were withdrawn. No other safety concerns, including thromboembolic events, were identified. In the prophylaxis group (n = 28), 67.9% were bleed free; all bleeds (n = 15) were treated with one N9-GP injection; and overall, spontaneous, and traumatic ABRs were low (median ABRs of 0.0, 0.0, and 0.0, respectively; modeled mean ABRs of 0.31, 0.08, and 0.23, respectively). Estimated mean FIX trough activity was 15.0%. CONCLUSION: We report an inhibitor incidence of 6.1%, which is within the expected range for PUPs with hemophilia B. No other safety concerns were identified; moreover, N9-GP provided effective hemostatic coverage.

Favorable pharmacokinetics in hemophilia B for nonacog beta pegol versus recombinant factor IX-Fc fusion protein: A randomized trial.

BACKGROUND AND OBJECTIVE: Nonacog beta pegol (N9-GP) and recombinant factor IX-Fc fusion protein (rFIXFc) are extended half-life rFIX compounds. We report the first single-dose pharmacokinetic trial of N9-GP and rFIXFc. PATIENTS/METHODS: Paradigm 7 was a multicenter, open-label, randomized, crossover trial in previously treated (>150 exposure days) adults with congenital hemophilia B (FIX activity ≤2%). Patients received single intravenous injections (50 IU/kg) of N9-GP and rFIXFc with at least 21 days between doses. Plasma FIX activity, predose, and at serial time points up to 240 hours postdose, was measured using validated one-stage clotting assays (SynthAFax for N9-GP; Actin FSL for rFIXFc) and a chromogenic assay (ROX factor IX) with normal human plasma as calibrator. The primary endpoint was area under the FIX activity-time curve from 0 to infinity, dose-normalized to 50 IU/kg (AUC0-inf,norm). RESULTS: Fifteen patients received study treatment. Based on FIX activity results from the one-stage clotting assays, estimated AUC0-inf,norm was significantly greater for N9-GP than rFIXFc (ratio: 4.39; P < 0.0001, based on a two-sided test on 5% significance level). In addition, N9-GP had a longer terminal half-life, two times higher incremental recovery at 30 minutes and maximum FIX activity (dose-normalized to 50 IU/kg) and six times higher FIX activity at 168 hours than rFIXFc. These findings were largely comparable with the chromogenic assay data and are consistent with published data for each compound. CONCLUSIONS: In this comparison, N9-GP demonstrated favorable pharmacokinetic characteristics versus rFIXFc, helping clinicians to understand differences between N9-GP and rFIXFc. REGISTRATION: This trial is registered with clinicaltrials.gov (NCT03075670) and the European Clinical Trials Database (EudraCT: 2016-001149-25).

Thymus size at 6 months of age and subsequent child mortality.

OBJECTIVE: To examine determinants of thymus size at age 6 months and investigate whether thymus size at this age is a determinant of subsequent mortality. STUDY DESIGN: Thymus size was measured by transsternal sonography in 923 6-month-old children participating in a measles vaccination trial in Guinea-Bissau. RESULTS: Thymus size was strongly associated with anthropometric measurements. Boys had larger thymuses than girls, controlling for anthropometry. Crying during sonography made the thymus appear smaller. Children who were not vaccinated with Bacille Calmette-Guérin (BCG) or were vaccinated with BCG in the preceding 4 weeks before inclusion into the study had larger thymuses. Children who had malaria or had been treated with chloroquine or Quinimax in the previous week before inclusion had smaller thymuses. Controlled for background factors associated with thymus size and mortality, small thymus size remained a strong and independent risk factor for mortality (hazard ratio = 0.31; 95% confidence interval = 0.18 to 0.52). CONCLUSIONS: Small thymus size at age 6 months is a strong risk factor for mortality. To prevent unnecessary deaths, it is important to identify preventable factors predisposing to small thymus size.

Recombinant FXIII (rFXIII-A2) Prophylaxis Prevents Bleeding and Allows for Surgery in Patients with Congenital FXIII A-Subunit Deficiency.

Recombinant factor XIII-A2 (rFXIII-A2) was developed for prophylaxis and treatment of bleeds in patients with congenital FXIII A-subunit deficiency. mentor™2 (NCT00978380), a multinational, open-label, single-arm, multiple-dosing extension to the pivotal mentor™1 trial, assessed long-term safety and efficacy of rFXIII-A2 prophylaxis in eligible patients (patients with severe [<0.05 IU/mL] congenital FXIII subunit A deficiency) aged ≥6 years. Patients received 35 IU/kg rFXIII-A2 (exact dosing) every 28 ± 2 days for ≥52 weeks. Primary endpoint was safety (adverse events including immunogenicity); secondary endpoints were rate of bleeds requiring FXIII treatment, haemostatic response after one 35 IU/kg rFXIII-A2 dose for breakthrough bleeds and withdrawals due to lack of rFXIII-A2 efficacy. Steady-state pharmacokinetic variables were also summarized. Elective surgery was permitted during the treatment period. Sixty patients were exposed to rFXIII-A2; their median age was 26.0 years (range: 7.0-77.0). rFXIII-A2 was well tolerated without any safety concerns. No non-neutralizing or neutralizing antibodies (inhibitors) against FXIII were detected. Mean annualized bleeding rate (ABR) was 0.043/patient-year. Mean spontaneous ABR was 0.011/patient-year. No patients withdrew due to lack of efficacy. Geometric mean FXIII trough level was 0.17 IU/mL. Geometric terminal half-life was 13.7 days. rFXIII-A2 prophylaxis provided sufficient haemostatic coverage for 12 minor surgeries without the need for additional FXIII therapy; eight procedures were performed within 7 days of the patient's last scheduled rFXIII-A2 dose, and four were performed 10 to 21 days after the last dose.

Randomized Trial of 2 Versus 1 Dose of Measles Vaccine: Effect on Hospital Admission of Children After 9 Months of Age.

BACKGROUND: Two doses of measles vaccine (MV) might reduce the nonmeasles mortality rate more than 1 dose of MV does. The effect of 2 versus 1 dose on morbidity has not been examined. Within a randomized trial of the effect of 2 doses versus 1 dose of MV on mortality in Guinea-Bissau, we investigated the effect on hospital admissions. METHODS: Children were randomly assigned 1:2 to receive MV at 4.5 and 9 months of age or the currently recommended dose at 9 months. We compared hospital admission rates among children between 9 and 18 months of age in a Cox regression model with age as the underlying time scale. Half of the children had received neonatal vitamin A supplementation (NVAS) in another trial. The beneficial effect of MV at 4.5 and 9 months on mortality was limited to children who had not received NVAS; therefore, we investigated the interaction of MV with NVAS on admission rates. RESULTS: Among 5626 children (2 doses of MV, 1960 children; 1 dose of MV, 3666), we identified 311 hospital admissions of children between 9 and 18 months of age. Overall, compared to 1 dose of MV, 2 doses reduced the risk of hospital admission for children who had not received NVAS (hazard ratio [HR], 0.66 [95% confidence interval (CI), 0.47-0.93]), but we found no effect among NVAS recipients (HR, 1.16 [95% CI, 0.82-1.63]) (P = .02 for interaction). CONCLUSIONS: The benefit of 2 doses of MV was limited to children who had not received NVAS. NVAS is not generally recommended; hence, an early 2-dose measles vaccination policy might reduce hospital admissions more than the current policy of providing the first MV at 9 months of age. TRIAL REGISTRATION: ClinicalTrials.gov identifier NCT00168558.

Increased female-male mortality ratio associated with inactivated polio and diphtheria-tetanus-pertussis vaccines: Observations from vaccination trials in Guinea-Bissau.

BACKGROUND: The 2-fold increase in female mortality after high-titer measles vaccine may have occurred because many children received diphtheria-tetanus-pertussis (DTP) vaccine or inactivated polio vaccine (IPV) after high-titer measles vaccine. OBJECTIVE: We examined whether DTP vaccine and IPV were associated with increased female mortality when they were the most recent vaccine administered to children who had not received measles vaccine. SETTING AND DESIGN: IPV was used as a control vaccine in 4 randomized trials of early measles vaccination (MV) with enrollment at 4-6 months of age conducted in Guinea-Bissau. Many children had not received all 3 DTP vaccinations before enrollment, and therefore received DTP after IPV or MV. We examined whether DTP vaccination status at enrollment affected the female-male mortality ratio. POPULATION: 9544 children enrolled in 4 trials. MAIN OUTCOME MEASURE: The female-male mortality ratio in different vaccine groups. RESULTS: Females had a higher mortality rate than males among children randomized to receive IPV (mortality rate ratio [MR] 1.52, 95% CI 1.02-2.28), but females had a similar mortality rate to males among children randomized to receive MV (MR 1.01, 0.69-1.46) and among children in the IPV group after they had received MV at 9 months of age or later (MR 0.88, 0.68-1.14). Children who had not received a third dose of DTP before enrollment (and were likely to receive DTP after MV or IPV) tended to have a higher mortality than children who had received all 3 doses of DTP (MR 1.30, 0.97-1.73). This effect was seen only among girls (MR 1.61, 1.08-2.40) and not among boys (MR 1.02, 0.67-1.54). Girls had a lower mortality when MV was the most recent vaccine received rather than DTP or IPV (MR 0.49, 0.28-0.87). CONCLUSIONS: Randomization to IPV was associated with higher female than male mortality. However, the increased female mortality might result from additional doses of DTP received after enrollment and before measles vaccination.

BCG vaccination scar associated with better childhood survival in Guinea-Bissau.

BACKGROUND: Recent studies have suggested that Bacille Calmette-Guerin (BCG) vaccination may have a non-specific beneficial effect on infant survival and that a BCG scar may be associated with lower child mortality. No study has previously examined the influence of BCG vaccination on cause of death. METHODS: Two cohorts (A and B) were used to describe the mortality pattern for children with and without BCG scar and to determine specific causes of death. In cohort A (n = 1813), BCG scar was assessed at 6 months of age and as previously described children with a BCG scar had lower mortality over the next 12 months than children with no BCG scar. In cohort B, 1617 children aged 3 months to 5 years of age had their BCG scar status assessed in a household-based survey and mortality was assessed during a 12-month period. Causes of death were determined by verbal autopsy (VA) and related to BCG scar status in a cause-specific hazard function. RESULTS: Controlling for background factors associated with mortality, there was lower mortality for children with a BCG scar than without in cohort B, the mortality ratio (MR) being 0.45 (95% CI 0.21-0.96). Exclusion of children exposed to TB did not have any impact on the result. In a combined analysis of cohorts A and B, the MR was 0.43 (95% CI 0.28-0.65) controlling for background factors. There were no large differences in distribution of the five major causes of death (malaria, pneumonia, acute diarrhoea, chronic diarrhoea, and meningitis/encephalitis) according to BCG scar status in the two cohorts. Having a BCG scar significantly reduced the risk of death from malaria [MR 0.32 (95% CI 0.13-0.76)]. CONCLUSIONS: A BCG scar is a marker of better survival among children in countries with high child mortality. BCG vaccination may affect the response to several major infections including malaria.

Survival of previously measles-vaccinated and measles-unvaccinated children in an emergency situation: an unplanned study.

BACKGROUND: Previous studies have suggested that standard measles vaccine may reduce mortality by more than the number of deaths thought to be caused by measles infection in areas with high mortality. However, these observations have not been based on randomized trials. METHODS: During the recent war in Guinea-Bissau, most children fled from the city of Bissau and immunization services in the country broke down for several months. We were performing a trial in which children were randomized at 6 months of age to receive either measles vaccine or inactivated polio vaccine. Because of the war many children did not receive the dose of measles vaccine planned for 9 months of age. We were able to monitor mortality during the war and after. RESULTS: Included in the study were 433 children 6 to 11 months of age. Fifteen children died (3.6%) during the first 3 months of the war before vaccination programs were resumed, 4 of 214 measles-vaccinated children and 11 of 219 children who had received inactivated polio vaccine. The effect of measles vaccine was marked for girls [mortality rate ratio (MR), 0.00; 95% confidence limits, 0.0 to 0.37], whereas there was no difference for boys (MR = 1.02; 95% confidence limits, 0.25 to 3.88). In a combined analysis controlling for factors that differed between the two groups, the MR for measles-vaccinated children was 0.30 (95% confidence limits, 0.08 to 0.87). Prolonging the period of observation to the end of 1998 or including the prewar period did not modify the significant beneficial effect of measles vaccine for girls. Twenty-two of the children in the cohort were reported to have had measles, 8 cases occurring during the 3 months of the war. Exclusion of measles cases in the analysis did not change the results; children who had received measles vaccine had a MR of 0.28 (95% confidence limits, 0.06 to 0.89) during the first 3 months of the war. CONCLUSIONS: Consistent with previous observational studies, measles vaccination was associated with a reduction in mortality that cannot be explained by the prevention of measles infection. This nonspecific beneficial effect was particularly strong for girls. Further studies are needed to examine the extent of nonspecific effects in settings with high mortality.

Hepatitis B vaccination associated with higher female than male mortality in Guinea-bissau: an observational study.

OBJECTIVE: Studies from high mortality areas have suggested that diphtheria-tetanus-pertussis may be associated with an increase in the mortality of girls relative to boys. We therefore examined whether hepatitis B vaccine (HBV) was associated with sex-specific differences in mortality. DESIGN: As part of a randomized trial of measles vaccine, a subcohort of 876 children was offered HBV at 7(1/2), 9 and 10(1/2) months of age. We examined whether this cohort differed in mortality rate and female-male mortality ratio compared with previous and subsequent birth cohort enrolled in the same trial. SETTING: Four districts in Bissau, the capital of Guinea-Bissau. SUBJECTS: Six annual birth cohorts of 8906 children registered in the study area and followed from 1(1/2) to 12 months of age between March 1995 and February 2001. Of these children, 6399 took part in a 2-dose measles vaccination trial; of those born between March 1996 and February 1997, 876 received HBV. MAIN OUTCOME MEASURES: (1) The mortality rate ratio (MR) between 7(1/2) and 12 months and 1(1/2) and 7(1/2) months old children; (2) the female-male MR among trial children having received HBV plus measles vaccine or only measles vaccine. RESULTS: In cohorts not receiving HBV, the MR for children 7(1/2)-12 and 1(1/2)-7(1/2) months of age was 0.97 "95% confidence interval (95% CI), 0.79-1.24", whereas the MR was 1.62 (95% CI 1.09-2.41) in the cohort receiving HBV at 7(1/2) months (test of homogeneity, P = 0.030). Among children enrolled in the measles vaccination trial, HBV-vaccinated children 7(1/2)-12 months of age had higher mortality than both prior and subsequent cohorts who had not received HBV (MR = 1.81; 95% CI 1.19-2.75), the difference being particularly strong for girls (MR=2.27; 95% CI 1.31-3.94). In the cohort who had received both HBV and measles vaccine, the female-male MR between 9 and 24 months of age was 2.20 (95% CI 1.07-4.54) compared with 0.96 (95% CI 0.70-1.32) in trial participants who had received measles vaccine only (test for homogeneity, P = 0.040). With longer follow-up, these tendencies remained the same. CONCLUSIONS: These comparisons suggested changes in the mortality pattern after the introduction of HBV, particularly for girls. Hence in areas with high mortality, HBV may affect girls' and boys' susceptibility to infections differently.

Low birth weight infants and Calmette-Guérin bacillus vaccination at birth: community study from Guinea-Bissau.

BACKGROUND: In developing countries, low birth weight (LBW) children are often not vaccinated with Calmette-Guérin bacillus (BCG) at birth. Recent studies have suggested that BCG may have a nonspecific beneficial effect on infant mortality. We evaluated the consequences of not vaccinating LBW children at birth in Guinea-Bissau. METHODS: Between 1989 and 1999, 7138 children born at the central hospital had a birth weight registered. We assessed BCG coverage until 3 years of age. Data on tuberculin skin test (TST) for 297 children and BCG scar for 1319 children in the study population were reanalyzed for differences between normal birth weight (NBW) children and LBW children. We assessed the effect of early BCG vaccination on mortality to 12 months of age. RESULTS: Among LBW children there were 1.5- to 3-fold more unvaccinated individuals than among NBW children up to 4 months of age. There was no overall difference between LBW and NBW children in TST or BCG scarring; LBW children vaccinated early may have had slightly reduced reactions to tuberculin. Among 845 LBW children, 182 had received BCG within the first week of life. Controlling for background factors and censoring at first diphtheria-tetanuspertussis vaccination, measles vaccination or at 6 months of age (whichever came first), the mortality rate ratio for BCG-vaccinated versus -unvaccinated LBW children was 0.17 (95% confidence interval, 0.06-0.49), with an even stronger effect for LBW children vaccinated in the first week of life (mortality rate ratio, 0.07; 95% confidence interval, 0.01-0.62). CONCLUSIONS: The policy of not vaccinating with BCG at birth had a negative impact on vaccination coverage for LBW children. Early BCG vaccination had no large negative impact on TST and BCG scarring. Mortality was lower for BCG-vaccinated than for unvaccinated LBW children controlling for available background factors. BCG vaccination of LBW children may have a beneficial effect on survival that cannot be explained by protection against tuberculosis. Future studies should examine possible adverse effects from equalizing BCG policy for LBW and NBW children.

Divergent female-male mortality ratios associated with different routine vaccinations among female-male twin pairs.

BACKGROUND: Observational studies have suggested that vaccinations have non-specific effects that differ by sex. In the absence of randomized trials, studies of female-male twin pairs would allow us to investigate whether an intervention had sex-specific effects on survival. We therefore examined mortality patterns among female-male twin pairs according to vaccination status. Design We identified female-male twin pairs using the population registers from one urban district and three rural studies from Guinea-Bissau and Senegal and examined the female-male mortality ratio (MR) according to the last vaccine received among pairs in which a death occurred before 18 months of age. As background information, we examined sex- and age-specific mortality patterns in the pre-vaccination era. Subjects In all, 626 female-male twin pairs identified between 1978 and 2000. RESULTS: There was no sex difference in mortality for boys and girls in the pre-vaccination era. In the combined analysis of all studies, the female-male MR was 0.25 (95% CI: 0.05, 0.93) for pairs having received Bacille Calmette-Guerin (BCG) as the last vaccine, 7.33 (95% CI: 2.20, 38.3) for pairs having received diphtheria, tetanus, pertussis (DTP) as the last vaccine, and 0.40 (95% CI: 0.04, 2.44) for pairs having received measles vaccine as the last vaccine. The female-male MR varied significantly for BCG compared with DTP (exact test of homogeneity, P < 0.001) and for DTP compared with measles vaccine (exact test of homogeneity, P = 0.001). CONCLUSION: Non-specific effects of routine vaccinations are likely to be important and influence sex-specific mortality patterns in areas with high mortality. The effects of vaccines need to be considered in the planning of immunization programmes for low-income countries.

The challenge of improving the efficacy of measles vaccine.

Despite a safe and effective measles vaccine, measles still claims an estimated 800,000 lives per year mostly among children in developing countries. This paper deals with strategies to improve vaccine efficacy and prevent unnecessary deaths, including considerations of one dose at 9 months strategy for developing countries, strain of vaccine, potency and number of doses of measles vaccine. After more than 20 years of measles immunisation in the developing world, the epidemiology of measles is radically changed, and the absence of measles epidemics might lead to waning immunity due to less clinical and subclinical infections boosting the antibody level. An increasing proportion of mothers are vaccinated, thus transferring a lower maternal antibody level to their infants who will be susceptible to measles at a younger age. The strategies to limit nosocomial measles infection and spread of measles epidemics are reviewed. Though the measles elimination programmes have been very effective in the Americas, it seems unlikely that they will be equally effective in the rest of the world. Even if eradication should be possible, it might be unwise to stop measles vaccination because the vaccine apparently has beneficial effects and because it would make measles a likely weapon for bio-terrorism. If we are unlikely to get rid of measles and measles vaccine, it might be wise to study further some of the many unanswered questions regarding the long-term effects of measles and measles vaccination.

Interaction between neonatal vitamin A supplementation and timing of measles vaccination: a retrospective analysis of three randomized trials from Guinea-Bissau.

BACKGROUND: In Guinea-Bissau we conducted three trials of neonatal vitamin A supplementation (NVAS) from 2002 to 2008. None of the trials found a beneficial effect on mortality. From 2003 to 2007, an early measles vaccine (MV) trial was ongoing, randomizing children 1:2 to early MV at 4.5 months or no early MV, in addition to the usual MV at 9 months. We have previously found interactions between vitamin A and vaccines. OBJECTIVE: We investigated whether there were interactions between NVAS and early MV. DESIGN: We compared the mortality of NVAS and placebo recipients: first, from 4.5 to 8 months for children randomized to early MV or no early MV; and second, from 9 to 17 months in children who had received two MV or one MV. Mortality rates (MR) were compared in Cox models producing mortality rate ratios (MRR). RESULTS: A total of 5141 children were randomized to NVAS (N=3015) or placebo (N=2126) and were later randomized to early MV (N=1700) or no early MV (N=3441). Between 4.5 and 8 months, NVAS compared with placebo was associated with higher mortality in early MV recipients (MR=30 versus MR=0, p=0.01), but not in children who did not receive early MV (p for interaction between NVAS and early MV=0.03). From 9 to 17 months NVAS was not associated with mortality. Overall, from 4.5 to 17 months NVAS was associated with increased mortality in early MV recipients (Mortality rate ratio=5.39 (95% confidence interval: 1.62, 17.99)). CONCLUSIONS: These observations indicate that NVAS may interact with vaccines given several months later. This may have implications for the planning of future child intervention programs.

A randomized trial of an early measles vaccine at 4½ months of age in Guinea-Bissau: sex-differential immunological effects.

BACKGROUND: After measles vaccine (MV), all-cause mortality is reduced more than can be explained by the prevention of measles, especially in females. OBJECTIVE: We aimed to study the biological mechanisms underlying the observed non-specific and sex-differential effects of MV on mortality. METHODS: Within a large randomised trial of MV at 4.5 months of age blood samples were obtained before and six weeks after randomisation to early MV or no early MV. We measured concentrations of cytokines and soluble receptors from plasma (interleukin-1 receptor agonist (IL-1Ra), IL-6, IL-8, IL-10, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein (MCP)-1, soluble urokinase-type plasminogen activator receptor), and secreted cytokines (interferon-γ, TNF-α, IL-5, IL-10, IL-13, IL-17) after in vitro challenge with innate agonists and recall antigens. We analysed the effect of MV in multiple imputation regression, overall and stratified by sex. The majority of the infants had previously been enrolled in a randomised trial of neonatal vitamin A. Post hoc we explored the potential effect modification by neonatal vitamin A. RESULTS: Overall, MV versus no MV was associated with higher plasma MCP-1 levels, but the effect was only significant among females. Additionally, MV was associated with increased plasma IL-1Ra. MV had significantly positive effects on plasma IL-1Ra and IL-8 levels in females, but not in males. These effects were strongest in vitamin A supplemented infants. Vitamin A shifted the effect of MV in a pro-inflammatory direction. CONCLUSIONS: In this explorative study we found indications of sex-differential effects of MV on several of the plasma biomarkers investigated; in particular MV increased levels in females, most strongly in vitamin A recipients. The findings support that sex and micronutrient supplementation should be taken into account when analysing vaccine effects. TRIAL REGISTRATION: clinicaltrials.gov number NCT 00168545.