BCG scarring and improved child survival: a combined analysis of studies of BCG scarring.

Bacillus Calmette-Guérin (BCG) vaccine against tuberculosis (TB) is recommended at birth in TB-endemic areas. Currently, BCG vaccination programmes use "BCG vaccination coverage by 12 months of age" as the performance indicator. Previous studies suggest that BCG-vaccinated children, who develop a scar, have better overall survival compared with BCG-vaccinated children, who do not develop a scar. We summarized the available studies of BCG scarring and child survival. A structured literature search for studies with original data and analysis of BCG scarring and mortality were performed. Combined analyses on the effect of BCG scarring on overall mortality. We identified six studies covering seven cohorts, all from Guinea-Bissau, West Africa, with evaluation of BCG scarring amongst BCG-vaccinated children and follow-up for mortality. Determinants of BCG scarring were BCG strain, intradermal injection route, size of injection wheal, and co-administered vaccines and micronutrients. In a combined analysis, having a BCG scar vs. no BCG scar was associated with a mortality rate ratio (MRR) of 0.61 (95% CI: 0.51-0.74). The proportion with a BCG scar varied from 52 to 93%; the estimated effect of a BCG scar was not associated with the scar prevalence. The effect was strongest in the first (MRR = 0.48 (0.37-0.62)) and second (MRR = 0.63 (0.44-0.92)) year of life, and in children BCG-vaccinated in the neonatal period (MRR = 0.45 (0.36-0.55)). The effect was not explained by protection against TB. Confounding and genetic factors are unlikely to explain the strong association between BCG scarring and subsequent survival. Including "BCG scar prevalence" as a BCG vaccination programme performance indicator should be considered. The effect of revaccinating scar-negative children should be studied.

Recombinant factor XIII prophylaxis is safe and effective in young children with congenital factor XIII-A deficiency: international phase 3b trial results.

Essentials Prophylaxis is the standard of care for congenital factor XIII-A (FXIII-A) deficiency. Six children with FXIII-A deficiency received once-monthly prophylaxis with recombinant FXIII-A. Prophylaxis was well tolerated and no anti-FXIII antibodies were detected. Prophylaxis was effective with an annualized bleeding rate of zero. SUMMARY: Background Factor XIII deficiency is a rare, severe congenital bleeding disorder. Monthly prophylaxis with recombinant FXIII A-Subunit (rFXIII) has demonstrated favorable safety and efficacy in patients aged ≥ 6 years, and may similarly benefit younger children. Objective To evaluate the long-term safety and efficacy of rFXIII in children aged < 6 years with congenital FXIII A-subunit deficiency. Patients/methods Six children, who had previously completed a single-dose pharmacokinetic trial of rFXIII, received 35 IU kg-1 rFXIII every 28 days (± 2 days) for a minimum of 52 weeks, and were evaluated for bleeding and adverse events. The Berichrom FXIII activity assay was used to monitor FXIII activity. Results The children, three girls and three boys, had an average age of 3.0 years (range: 1-4 years) at enrollment. The total treatment duration was 1.8-3.5 years, giving a total of 16.6 patient-years. No antibody development, thromboembolic events or allergic reactions occurred. There were 93 mild and seven moderate adverse events. Two adverse events (lymphopenia and gastroenteritis) were reported as probably or possibly related to rFXIII in two children. Two serious adverse events, unrelated to rFXIII, were reported in a single child, each related to head injury, and neither resulting in intracranial hemorrhage. The geometric mean FXIII activity trough was 0.19 IU mL-1 . No bleeding episodes requiring treatment with an FXIII-containing hemostatic agent occurred during the trial; thus, the annualized bleeding rate was 0. Conclusions Consistent with data from older age groups, prophylaxis with rFXIII appears to be safe and effective in young children with congenital FXIII A-subunit deficiency.

Comparison of F13A1 gene mutations in 73 patients treated with recombinant FXIII-A2.

INTRODUCTION: Congenital factor XIII (FXIII) deficiency is a rare, autosomal recessive bleeding disorder usually caused by mutations in the F13A1 gene that produce a severe quantitative (type I) deficiency of the FXIII-A subunit. AIM: To determine the genotypes of patients with severe FXIII-A deficiency treated with recombinant FXIII-A subunit (rFXIII-A2 ) participating in three international efficacy and safety trials. METHODS: We determined the genotypes of 73 patients in total; 32 had already undergone genotype analysis and were known to carry F13A1 mutations that have been previously reported in the literature. Mutation screening was performed in 41 patients with unknown genetic status using direct sequencing. RESULTS: In total, 51 distinct mutations in 73 patients were identified. Two patients showed a phenotype of severe FXIII-A deficiency, despite having heterozygous missense mutations. Two siblings carried a missense mutation in the F13A1 gene (p.Ser296Arg) in combination with a novel, probably polymorphic variant of the F13B gene (p.Ser654Phe). Molecular modelling of five F13A1 novel missense mutations (p.Leu171Phe, p.Glu204Lys, p.Leu276Phe, p.Asp405His and p.Gly411Cys) predicted a damaging effect of these mutations on protein structure. Although five patients treated with rFXIII-A2 had transient, low-titre, non-neutralizing anti-rFXIII antibodies, no patients developed FXIII-neutralizing antibodies (inhibitors). CONCLUSION: The identified mutations are causally implicated in severe FXIII deficiency; however, they do not appear to increase the risk of neutralizing antibody development against rFXIII-A2 .

A comparison of ex vivo cytokine production in venous and capillary blood.

We performed a randomized study of the immunological effects of an early measles vaccine given at 4.5 months of age and aimed to obtain venous samples from the infants at baseline and 6 weeks later. If this was not feasible, a capillary sample was obtained. We analysed baseline samples from the first 50 children enrolled in the study to investigate the potential differences in ex vivo cytokine production between venous blood and capillary blood. We also obtained paired venous and capillary blood samples from 11 adult volunteers. Whole blood was stimulated with lipopolysaccharide (LPS) [a Toll-like receptor (TLR)-4 ligand], (S)-(2, 3-bis (palmitoyloxy)-(2-RS)-propyl)-N-palmitoyl-(R)-Cys-(S)-Ser-(S)-Lys4-OH, trihydrochloride (PAM3Cys) (a TLR-2 ligand), phytohaemagglutinin (PHA) or purified protein derivative (PPD). Cytokine concentrations in the supernatants were assessed by a multiplexed assay and were compared between venous and capillary samples in both infants and adults. The production of both the pro- and the anti-inflammatory cytokines, tumour necrosis factor (TNF)-alpha and interleukin (IL)-10, was higher in cultures of capillary blood compared with venous blood. This was found in non-stimulated control samples as well as in blood stimulated with PAM3Cys and PPD. Adults produced more IL-5 in venous blood than in capillary blood upon PHA stimulation. We found no other difference in the levels of IL-5 or IFN-gamma between venous and capillary blood. In capillary blood we found sex differences in response to PHA but this was not the case in venous blood. We found significant differences in the production of cytokines between venous and capillary blood. Such differences should be taken into account when setting up immuno-epidemiological studies.

Beneficial non-targeted effects of BCG--ethical implications for the coming introduction of new TB vaccines.

Non-targeted effect of BCG: Several recent studies suggest that BCG has beneficial non-targeted effects on general child survival in low-income countries. Studies of the effect of BCG on morbidity in humans are scarce; some found a positive effect of BCG and others show no effect. Non-targeted effects of vaccines-possible bias and confounding: The major argument against comparing vaccinated and unvaccinated groups is that there is a beneficial social selection bias for vaccinated children-the "Healthy vaccinee effect". However, controlling for various social and health-related background factors in the survival analyses had no effect on the estimates, making this source of bias less likely. A more powerful argument that the findings are not due to the healthy vaccinee effect is that differential non-targeted effects of other vaccines have been observed; diphteria-tetanus-pertussiss vaccination has marked negative effects on child survival, whereas measles vaccine has a positive effect in several studies. Several studies have shown better survival for children reacting to their BCG vaccination with a BCG scar or tuberculin skin test reaction (TST). It could be argued that the reacting children were immunologically stronger and therefore more likely to survive-the "Healthy reactor effect". However, recent findings show that a BCG scar and a TST reaction depend to a large extent on the vaccination technique. Hence, the BCG responses may reflect a true vaccine effect and not merely the health status of the children. Since HIV-1 has been shown to suppress both TST and BCG scar reaction in response to BCG, it is an obvious contributor to the healthy reactor effect, but excluding deaths of children with HIV-1 infection from analysis did not affect the beneficial effect of having a positive TST. Excluding children exposed to tuberculosis (TB) in the household did not affect the estimates either. Furthermore, there are strong sex-differential effects of BCG in both mortality and morbidity data, BCG being more beneficial for girls. These observations cannot consistently be explained by the healthy vaccinee or healthy reactor effects. Ethical implications: For future TB-vaccine studies, these findings imply that: These recommendations might be considered to delay or to be a too large obstacle for the development and trials of new TB vaccines. However, most of the non-targeted beneficial effects of BCG have been observed in children below 2 years of age, which is not a long follow-up time in a TB-vaccine trial. Furthermore, considering the difficulty in setting the TB diagnose in children and the lack of reliable TB-protection markers, it does not seem unreasonable to argue for monitoring of general morbidity and survival in future TB-vaccine trials.

Bacillus Calmette-Guérin vaccination and infant mortality.

When the bacillus Calmette-Guérin (BCG) vaccine was introduced in the 1920s, it was suggested that BCG occasionally had nonspecific beneficial effects on mortality beyond the specific protection against tuberculosis. Considering that BCG has since then become the most used vaccine in the world, surprisingly few studies have been undertaken into the effect of BCG on general mortality and morbidity. Recent studies suggest that BCG has beneficial nontargeted effects on general infant morbidity and mortality in low-income countries, often with the most pronounced effect among girls. These observational findings are supported by early trials in which children were randomized or alternated to BCG vaccination. Furthermore, a BCG scar and a positive tuberculin reaction are related to better survival among BCG-vaccinated children in low-income countries, especially for girls. The findings are not explained by frailty bias, in other words, that healthy children are more likely to receive BCG vaccination. A nonspecific, gender-differential effect of BCG on general infant mortality may have large implications for tuberculosis vaccine research and routine vaccination policy.

BCG vaccination among West African infants is associated with less anergy to tuberculin and diphtheria-tetanus antigens.

To examine risk factors for anergy, delayed-type hypersensitivity was assessed among 884 infants participating in a vaccine trial in Guinea-Bissau. The infants were skin-tested at 7.5 months of age with a panel of seven intradermal antigens. Risk factors for anergy to tuberculin or anergy to both the diphtheria and tetanus antigens were determined in relation to Bacillus Calmette-Guérin (BCG) vaccination, diphtheria-tetanus-pertussis (DTP) vaccination, and measles vaccination. We found sick children to be more anergic to tuberculin and diphtheria-tetanus antigens than healthy children (OR=2.49 (95% confidence interval 1.40-4.55)). There was a higher prevalence of anergy to tuberculin in the rainy season than in the dry season (OR=1.67 (1.25-2.23)). Children who had taken antimalarials within the last week had a higher prevalence of anergy to tuberculin (OR=1.41 (1.02-1.92)). BCG vaccination was significantly associated with less anergy to tuberculin and diphtheria-tetanus antigens (OR=0.42 (0.28-0.63), OR=0.77 (0.60-0.99), respectively). Children vaccinated with BCG before 1 month of age were more anergic to tuberculin than children vaccinated after 1 month (OR=1.61 (1.19-2.19)). DTP vaccination was associated with less anergy to diphtheria-tetanus antigens (OR=0.40 (0.32-0.49)), but not to tuberculin. Children with a positive reaction to tuberculin were less likely to be anergic to diphtheria-tetanus antigens (OR=0.36 (0.26-0.49)) than children with a negative tuberculin reaction. Children who were vaccinated with BCG before they received their last DTP vaccine were less anergic to diphtheria-tetanus antigens (OR=0.40 (0.16-0.88)) than other DTP-vaccinated children. In conclusion, current disease, rainy season, age below 1 month of age at the time of BCG vaccination, and administration of chloroquine or quinimax within the last 7 days were risk factors for anergy to tuberculin among 7.5-month-old infants. BCG vaccination and a positive tuberculin reaction were associated with a lower prevalence of anergy to both tuberculin and diphtheria-tetanus. Thus, BCG vaccination may contribute to better cell-mediated immune responses among infants.

Measles antibody responses after early two dose trials in Guinea-Bissau with Edmonston-Zagreb and Schwarz standard-titre measles vaccine: better antibody increase from booster dose of the Edmonston-Zagreb vaccine.

In Guinea-Bissau, children were randomised at 6 months of age to receive either two doses of standard-titre measles vaccine at 6 and 9 months of age or an inactivated polio vaccine at 6 months and standard-titre measles vaccine at 9 months of age. During the first 5 months, children received Edmonston-Zagreb (EZ) vaccine and during the following 11 months, the Schwarz (SW) vaccine. Five percent of the mothers, 74% of children at 6 months of age, and 92% of unvaccinated children at 9 months of age had unprotective levels (<125 mIU/ml) of measles antibodies. Among children receiving EZ vaccine, 1% were unprotected at 18 months of age after either two (3/240) or one (3/211) doses of vaccine, the geometric mean measles antibody titre (GMT) being approximately 1550 mIU/ml in both groups. Among those receiving SW vaccine 9% (34/365) and 3% (9/310) were unprotected at 18 months of age in the two-dose and the one-dose groups (RR = 3.21 (95% confidence interval (CI) 1.56-6.58)), respectively. The GMT was higher after one dose of SW vaccine at 9 months of age (2491 mIU/ml) than after two doses of SW vaccine (1125 mIU) (P < 0.001). In the EZ vaccine group, there was no significant difference in antibody level for children vaccinated in the presence of high or low levels of maternal antibodies, whereas there was a marked difference in the SW group. The second EZ vaccine induced a significant antibody increase between 9 months of age (1191 mIU) and 18 months of age (1602 mIU, P=0.011), whereas antibody levels tended to decline from 9 months (1243 mIU) to 18 months of age (998 mIU, P = 0.124) after the second dose of SW vaccine. Conclusively, after two doses of EZ measles vaccine more children were protected at 18 months of age than after two doses of SW. One dose of SW provided the highest antibody response, but a higher proportion of unprotected than one or two doses of EZ. The EZ vaccine was less sensitive to maternal antibodies, and able to increase the antibody response by revaccination, while the second SW vaccine resulted in an unchanged or lower antibody response.

Early two-dose measles vaccination schedule in Guinea-Bissau: good protection and coverage in infancy.

BACKGROUND: Previous studies from Africa have suggested that there is little benefit to be gained from early two-dose measles vaccination schedules. Two-dose schedules have been associated with no improvement in coverage due to immunization of the same individuals on both occasions, low return rate, high refusal rate, low vaccine efficacy, and fear of blunting of the antibody response. Because of the poor results achieved previously with two-dose measles vaccination schedules, we studied patterns of participation, reasons for non-participation, vaccination coverage and relative efficacy of a one-dose versus a two-dose schedule in connection with the implementation of an early two-dose trial in Guinea-Bissau. METHODS: Children born from September 1994 to January 1996 were randomized into two groups receiving either two doses of measles vaccine at 6 and 9 months or one dose of inactivated polio vaccine (IPV) at 6 months and measles vaccine at 9 months. RESULTS: At 6 months of age 86% (1869/2181) of the children participated, and at 9 months of age participation was 87% (1775/2035). The return rate for obtaining a second dose of vaccine was 93% (1647/1773). The main reason for not participating was travelling (78%). Around 50% of those who did not take part in one vaccination took part in the other. When only children participating the first time they were called for a measles vaccination were included, the measles vaccination coverage in the one-dose group was 59% versus 80% in the two-dose group, i.e. a 50% reduction in the risk of not being vaccinated (relative risk [RR] 0.50; confidence interval [CI]: 0.43-0.57). Few measles cases have occurred in the study area since the implementation of the trial making precise estimation of the relative efficacy of the two vaccine strategies difficult, but all seven clinically diagnosed measles cases occurred in the one-dose group making the relative efficacy for the two-dose group compared with the one-dose group 100% (95% CI: 35%-100%; two-tailed P = 0.016). When including maternal reports, the relative efficacy was 90% (95% exact confidence interval; two-tailed P = 25%-97%, P = 0.022). CONCLUSION: In this study of a two-dose measles immunization schedule at 6 and 9 months of age there was no sign of low participation or poor return rates. The risk of not being vaccinated was lower in the two-dose group than in the one-dose group, and the relative efficacy of a two-dose versus a one-dose schedule was high. Although our results were obtained within a trial where dedicated personnel informed every participant personally about the study, we believe our results indicate that with thorough information about the population it may be possible to achieve a higher coverage with a two-dose measles vaccination schedule than a one-dose schedule. A two-dose schedule may be a feasible way to resolve the problems of low coverage and severe measles infection among infants.

PIP: Early 2-dose measles vaccination schedules in Africa have been associated with no improvement in coverage due to immunization of the same individuals on both occasions, low return rate, high refusal rate, low vaccine efficacy, and fear of blunting the antibody response. Findings are presented from the study of patterns of vaccination participation, reasons for nonparticipation, vaccination coverage, and the relative efficacy of a 1-dose versus 2-dose schedule in connection with the implementation of an early 2-dose trial in Guinea-Bissau. Children born from September 1994 to January 1996 were randomized into 2 groups receiving either 2 doses of measles vaccine at 6 and 9 months or 1 dose of inactivated polio vaccine (IPV) at age 6 months and measles vaccine at 9 months. 93% of children returned to receive a second dose of vaccine, with the main reason for nonparticipation being the need to travel. About half of the children who did not participate in 1 vaccination took part in the other. There was no sign of low participation or poor return rates in this study of a 2-dose measles immunization schedule at ages 6 and 9 months. The risk of not being vaccinated was lower in the 2-dose group than in the 1-dose group, and the relative efficacy of a 2-dose versus 1-dose schedule was high. These results indicate that with thorough information about the population it may be possible to achieve higher coverage with a 2-dose measles vaccination schedule than with a 1-dose schedule. A 2-dose schedule may be a feasible way of resolving the problems of low coverage and severe measles infection among infants.

Toxoplasmosis in Danish AIDS patients.

Infection with Toxoplasma gondii was studied in 600 patients with AIDS, diagnosed in the eastern part of Denmark from 1980 up to and including 1990. The median age was 38 years, and 223 (44%) had anti-T. gondii IgG antibodies. Of the patients seropositive to T. gondii 61 (27%) developed toxoplasma encephalitis (TE). Few patients received prophylactic treatment with sulfamethoxazole-trimetoprim. In total, 66 patients were diagnosed with TE. One had no serological test performed, and of the remaining 65, 4 (6%) had no anti-T. gondii IgG antibodies. The predictive value of a negative Sabin-Feldman dye test was 99%. The geometric mean dye test titer was higher in patients with TE than in patients without TE. Of the patients with TE 34% had serological reactivation of their T. gondii infection at the time of TE diagnosis, and 34% had detectable T. gondii-specific antibodies in the cerebrospinal fluid. Specific IgM antibodies were found to have little value in the diagnosis of TE, as only 3% had detectable IgM antibodies. Acute toxoplasmosis was the AIDS-defining diagnosis for 23 (35%) of the patients with TE. The median CD4 count at the time of TE was 30 x 10(6)/l, and the median survival time from diagnosis of TE was 9 months.