Lack of an inverse association between tuberculosis infection and atopy: by T-cell-based immune assay (RD1-ELISpot)

BCG Vaccination in Early Childhood and Risk of Atopic Disease: A Systematic Review and Meta-Analysis

Background

Several large-scale studies suggest that Bacille Calmette–Guerin (BCG) vaccination in early childhood may reduce the risk of atopic diseases, but the findings remain controversial. Here, we aimed to investigate the potential correlation between early childhood BCG vaccination and the risk of developing atopic diseases.

Methods

Eligible studies published on PubMed, EMBASE, and Cochrane CENTRAL were systematically sourced from 1950 to July 2021. Studies with over 100 participants and focusing on the association between BCG vaccine and atopic diseases including eczema, asthma, and rhinitis were included. Preliminary assessment of methods, interventions, outcomes, and study quality was performed by two independent investigators. Odds ratio (OR) with 95% confidence interval (CI) was calculated. Random effects of the meta-analysis were performed to define pooled estimates of the effects.

Results

Twenty studies with a total of 222,928 participants were selected. The quantitative analysis revealed that administering BCG vaccine in early childhood reduced the risk of developing asthma significantly (OR 0.77, 95% CI 0.63 to 0.93), indicating a protective efficacy of 23% against asthma development among vaccinated children. However, early administration of BCG vaccine did not significantly reduce the risk of developing eczema (OR 0.94, 95% CI 0.76 to 1.16) and rhinitis (OR 0.99, 95% CI 0.81 to 1.21). Further analysis revealed that the effect of BCG vaccination on asthma prevalence was significant especially in developed countries (OR 0.73, 95% CI 0.58 to 0.92).

Conclusion

BCG vaccination in early childhood is associated with reduced risk of atopic disease, especially in developed countries.

BCG scar, socioeconomic and nutritional status: a study of newborns in urban area of Makassar, Indonesia

Objective

To investigate factors that determine the response to Bacille Calmette–Guérin (BCG) vaccination in urban environments with respect to socioeconomic status (SES), prenatal exposure to infections or newborn's nutritional status.

Methods

The study was conducted in an urban area, in Makassar, Indonesia. At baseline, 100 mother and newborns pair from high and low SES communities were included. Intestinal protozoa, soil transmitted helminths, total IgE, anti‐Hepatitis A Virus IgG and anti‐Toxoplasma IgG were measured to determine exposure to infections. Information on gestational age, birth weight/height and delivery status were collected. Weight‐for‐length z‐score, a proxy for newborns adiposity, was calculated. Leptin and adiponectin from cord sera were also measured. At 10 months of age, BCG scar size was measured from 59 infants. Statistical modelling was performed using multiple linear regression.

Results

Both SES and birth nutritional status shape the response towards BCG vaccination at 10 months of age. Infants born to low SES families have smaller BCG scar size compared to infants born from high SES families and total IgE contributed to the reduced scar size. On the other hand, infants born with better nutritional status were found to have bigger BCG scar size but this association was abolished by leptin levels at birth.

Conclusion

This study provides new insights into the importance of SES and leptin levels at birth on the development of BCG scar in 10 months old infants.

Does BCG vaccination protect against childhood asthma? Final results from the Manchester Community Asthma Study retrospective cohort study and updated systematic review and meta-analysis

BACKGROUND

The Manchester Community Asthma Study (MANCAS) found a protective effect against the risk of wheeze at age 6 to 11 years for children given neonatal BCG vaccination. Our subsequent systematic review and meta-analysis suggested that BCG vaccination did not protect against allergic sensitization but might have exerted a protective effect against nonatopic asthma.

OBJECTIVES

We sought to assess whether the protective effect of BCG vaccination on wheeze observed in the MANCAS cohort was maintained at age 13 to 17 years and to incorporate the findings from this final MANCAS analysis into an updated systematic review and meta-analysis.

METHODS

BCG vaccination status was determined from health records and respiratory outcomes from questionnaire responses. We updated the systematic review and used fixed-effects and random-effects modeling to undertake meta-analyses.

RESULTS

There were 1608 participants in the final MANCAS analysis. The 12-month prevalence of wheeze was 15.1%. There was no difference in prevalence between those who were and were not BCG vaccinated (15.8% vs 14.3%; relative risk, 1.05; 95% CI, 0.94-1.19). The updated meta-analysis incorporated 4 new studies: this showed that the protective effect of BCG vaccination against the development of asthma identified in our previous meta-analysis was attenuated (odds ratio, 0.95; 95% CI, 0.89-1.00). No protective effect of BCG was seen for sensitization, eczema/atopic dermatitis, rhinoconjunctivitis, or allergy in general.

CONCLUSIONS

Taken together, the final results of the MANCAS cohort and the updated systematic review and meta-analysis provide clearer evidence that any protective effect of BCG vaccination on childhood asthma is likely to be transient.

Does BCG vaccination protect against the development of childhood asthma? A systematic review and meta-analysis of epidemiological studies

BACKGROUND

Results have been conflicting as to whether Bacillus Calmette-Guérin (BCG) vaccine, a non-specific stimulator of the immune function, protects, predisposes or is unrelated to the development of childhood asthma. In this systematic review and meta-analysis, we qualitatively and quantitatively appraised the epidemiological evidence.

METHODS

Eligible studies were identified using a search strategy that included a computerized literature search and a manual search of each article's reference list, up to June 2008. A total of 23 studies were included (10 cohort, 5 case-control and 8 cross-sectional). Each study was summarized and rated for methodological quality. Pooled odds ratio (OR) estimates and 95% confidence intervals (CIs) were calculated using fixed-effects (FE) or random-effects (RE) models; if heterogeneity was present, the latter was used. Three indicators of BCG exposure were considered including BCG vaccination, tuberculin response and scar diameter.

RESULTS

The pooled estimate of association for 23 studies reporting on any of the three indicators suggested a protective effect of BCG exposure on childhood asthma occurrence. The studies were heterogeneous, especially when tuberculin response was considered. Restriction to a subgroup of 16 studies that considered BCG vaccination indicated a protective effect with no evidence of heterogeneity. The overall pooled OR using an FE model was 0.86 (95% CI 0.79-0.93). Exclusion of three studies with the lowest quality scores showed a similar association.

CONCLUSION

These results strengthen the epidemiological evidence in support of the hypothesis that exposure to the BCG vaccine in early life prevents asthma, possibly through a modulation of the immune maturation process.

No association between tuberculin skin test and atopy in a bacillus Calmette-Guérin vaccinated birth cohort

Previously, an inverse association was suggested between mycobacterial infection and atopy. We aimed to determine the association between tuberculin skin test (TST) and allergic manifestations in a birth cohort where all infants were vaccinated with bacillus Calmette-Guérin (BCG) at birth. Newborns were enrolled randomly and prospectively followed up for a period of 5 yr. Information on family history and environmental factors was obtained at birth, International Study of Asthma and Allergies in Childhood asthma questionnaire, physical examination, skin prick test to common inhalant and food allergens and TST were performed at 2 and 5 yr of age. Positive TST reactivity was defined as an induration of > or = 10 mm. A total of 399 newborns were enrolled, 293 and 125 were available for a followup visit at 2 and 5 yr of age respectively. The prevalence of ever asthma, rhinitis and allergen sensitization tended to increase while eczema decreased with time. No significant association was found between TST reactivity and ever and current wheeze, doctor diagnosed asthma or atopic sensitization both at 2 and 5 yr of age. This prospectively designed birth cohort study did not confirm the previously suggested inverse correlation between TST reactivity and atopic sensitization or any allergic manifestations in Turkish children vaccinated with BCG at birth.