Antibody response to hepatitis B vaccine in HIV-exposed infants in Malawi and correlation with HBV infection acquisition

Immune response to hepatitis B vaccine among children under 5 years in Africa: a meta-analysis

BACKGROUND

Hepatitis B virus (HBV) infection in Africa is mostly acquired before the age of 5 years through vertical or horizontal routes. While all the countries in the World Health Organization African region have introduced HBV vaccination into their national immunization programs, the rate of protective immune response to HBV vaccine among children in Africa has not been systematically synthesized. In this study, we estimated the HBV vaccine seroprotection rate (defined as anti-HBs titer ≥ 10 IU/L) and the associated factors among under-five children who completed a primary series of HBV vaccination in Africa.

METHODS

We systematically searched PubMed, Web Science, and Scopus databases from inception to May 2022 for potentially eligible studies. The pooled seroprotection rate was estimated using a random-effects model with Freeman-Tukey double arcsine transformation and the associated factors were examined using odds ratio estimated by the DerSimonian and Laird method.

RESULTS

From the 1063 records identified, 29 studies with a total sample size of 9167 under-five children were included in the meta-analysis. The pooled seroprotection rate was 89.23% (95% CI   85.68-92.33%, I2 = 95.96%, p < 0.001). In the subgroup analyses, there was a significant difference in the rate by the assay method, vaccine dose, and vaccine combination. HIV-positive children had lower odds of achieving seroprotection when compared with HIV-negative children (OR = 0.22, 95%CI   0.12-0.40).

CONCLUSIONS

The majority of under-five children in Africa achieved seroprotection after completing three or four doses of HBV vaccine. However, the rate was lower among children living with HIV. This calls for interventions to timely identify and address nonresponse to HBV vaccine, particularly among immunosuppressed children.

Undetectable Anti-HBs Antibodies: Need of a Booster Dose for HIV-1-Infected Individuals

HBV vaccination effectively prevents HBV transmission and the development of liver cancer. Disease progression and liver-related complications are more common in HIV-1/HBV co-infected than HBV mono-infected individuals. A considerable body of literature, which will be reviewed here, indicates that response to HBV vaccine is suboptimal in HIV-1-infected individuals and that the poor maintenance of protective immunity to HBV vaccines in these individuals is an important medical issue. Several factors affect HBV vaccine response during HIV-1 infection including CD4+ T cell counts, B cell response, vaccine formulation, schedules, and timing of antiretroviral therapy (ART). The initial response to HBV vaccination also plays a critical role in the sustainability of antibody responses in both HIV-1-infected and uninfected vaccinees. Thus, regular follow-up for antibody titer and a booster dose is warranted to prevent HBV transmission in HIV-1 infected people.

HIV-exposed infants with EBV infection have a reduced persistence of the immune response to the HBV vaccine

Background

In sub-Saharan African countries Epstein Barr virus (EBV) infection occurs in early childhood. We aim to investigate the factors associated with EBV acquisition and the impact of EBV infection on the humoral response to HBV vaccination in infants born from HIV-positive, antiretroviral-treated mothers in Malawi.

Methods

A total of 149 HIV-exposed infants were included in this longitudinal study. EBV anti-VCA IgG were measured using an ELISA assay. The EBV seroconversion was correlated with the maternal viro-immunological conditions, with infant growth and immunological vulnerability, and with the humoral response to the HBV vaccine.

Results

No infant was EBV-positive at 6 months (n. 52 tested). More than a third of infants (49/115 or 42.6 %) on study beyond 6 months seroconverted at 12 months. At 24 months, out of 66 tested infants, only 13 remained EBV-uninfected, while 53 (80.3 %) acquired EBV infection, rising the total proportion of EBV seroconversion to 88.7 % (102/115 infants). EBV seroconversion was significantly associated with a low maternal educational status but had no impact on infant growth or vulnerability to infections. Reduced HBsAb levels and accelerated waning of antibodies were associated with early EBV seroconversion.

Conclusions

We found a heterogeneous timing of acquisition of EBV with the majority of infants born from HIV + mothers acquiring infection after 6 months. Anti-HBs levels were lower and appeared to wane faster in infants acquiring EBV infection.

Immune response to the hepatitis B vaccine among HIV-infected adults in Uganda

BACKGROUND

Co-infection with hepatitis B virus (HBV) and human immunodeficiency virus (HIV) is common in sub-Saharan Africa (SSA) and can rapidly progress to cirrhosis and hepatocellular carcinoma. Recent data demonstrate ongoing HBV transmission among HIV-infected adults in SSA, suggesting that complications of HIV/HBV co-infection could be prevented with HBV vaccination. Because HBV vaccine efficacy is poorly understood among HIV-infected persons in SSA, we sought to characterize the humoral response to the HBV vaccine in HIV-seropositive Ugandan adults.

METHODS

We enrolled HIV-infected adults in Kampala, Uganda without serologic evidence of prior HBV infection. Three HBV vaccine doses were administered at 0, 1 and 6 months. Anti-HBs levels were measured 4 weeks after the third vaccine dose. "Response" to vaccination was defined as anti-HBs levels ≥ 10 IU/L and "high response" as ≥ 100 IU/L. Regression analysis was used to determine predictors of response.

RESULTS

Of 251 HIV-positive adults screened, 132 (53%) had no prior HBV infection or immunity and were enrolled. Most participants were women [89 (67%)]; median (IQR) age was 32 years (27-41), and 68 (52%) had received antiretroviral therapy (ART) for > 3 months. Median (IQR) CD4 count was 426 (261-583), and 64 (94%) of the 68 receiving ART had undetectable plasma HIV RNA. Overall, 117 (92%) participants seroconverted to the vaccine (anti-HBs ≥ 10 IU/L), with 109 (86%) participants having high-level response (anti-HBs ≥ 100 IU/L). In multivariate analysis, only baseline CD4 > 200 cells/mm3 was associated with response [OR = 6.97 (1.34-34.71), p = 0.02] and high-level response [OR = 4.25 (1.15-15.69)], p = 0.03].

CONCLUSION

HBV vaccination was effective in eliciting a protective humoral response, particularly among those with higher CD4 counts. Half of the screened patients did not have immunity to HBV infection, suggesting a large at-risk population for HBV infection among HIV-positive adults in Uganda. Our findings support including HBV vaccination as part of routine care among HIV-positive adults.

Hepatitis B virus prevalence and vaccine antibody titers in children HIV exposed but uninfected in Botswana

Background

Botswana introduced the HBV vaccine at birth for all newborns in 2000. To the best of our knowledge, since the introduction of HBV vaccination, there have been limited data for vaccine response to HBV and its impact on early childhood HBV infections among children HIV exposed but uninfected in Botswana.

Aims

To determine the prevalence of hepatitis B surface antigen (HBsAg) and HBV vaccine response in 18 months old children HIV exposed but uninfected in Botswana.

Methods

Stored plasma samples from 304 children at 18 months of age and 287 mothers from delivery were tested for HBsAg. Mothers with positive HBsAg had HBV DNA level tested, and their HBV genotypes were determined by amplifying a 415-base pair (bp) region of the surface gene. Plasma samples from children exposed to HIV were tested for hepatitis B surface antibody (anti-HBs) titers.

Results

No children (0 of 304) were positive for HBsAg at 18 months while 5 (1.74%) of 287 HIV-positive mothers were HBsAg positive. Four of the HBsAg positive mothers were infected with genotype A1, while 1 was infected with genotype E. The median anti-HBs titer in children was 174 mIU/mL [QR: 70, 457]. Three (1.1%) of 269 children had an inadequate vaccine response (<10 mIU/mL), while 266 (98.9%) of 269 had protective immunity. However, when using the ≥100mIU/mL threshold, only 170 (63.2%) of 269 children had complete protection.

Conclusion

No HBsAg positivity was identified in a cohort of children HIV exposed but uninfected. The absence of HBsAg positives was associated with good HBV vaccine responses and low maternal HBsAg prevalence in Botswana.