Observational study of vaccine effectiveness 20 years after the introduction of universal hepatitis B vaccination in Tunisia

Presumed Protective Role for Anti-Hepatitis B Virus Antibodies Against COVID-19 Severe Cases: A Clinical Study Confirming in silico Hypothesis

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for COVID-19 disease which is known to have a broad clinical spectrum, from asymptomatic to critical presentation leading to death. Many researchers have investigated the factors impacting the course of the disease. Our previous in silico study suggested a possible protective effect of Hepatitis B, Tetanus and Measles vaccines against COVID-19. In continuity, we conducted a cross-sectional clinical study in order to confirm our in silico assumptions regarding the HBs-Ag antibodies.

Methods

A representative sex- and age-matched sample of patients with confirmed COVID-19 was selected (n = 340). All clinical presentations were equally represented. Using an ELISA test, each patient benefited of a serology for the detection and measurement of the anti-HBs specific IgG antibodies. The obtained results allowed determining the different correlations between these antibody titers and the disease severity. The R^® software and the MedCalc^® software served to calculate the Spearman's coefficient of rank correlation (rho) for the obtained titers per severity group as well as the different other calculations and figure representations.

Results

A significant positive correlation was found with the anti-HBs titers (rho = 0.107; p = 0.04). High anti-HBs titers were significantly associated with the mild presentation of COVID-19. A significant difference was found between the obtained titers per severity class (chi-2 test, p = 0.03).

Discussion/Conclusion

Our findings demonstrated that anti-HBs titers were significantly higher for patients having mild COVID-19 presentations. We presume that being immunized against the HB may play a protective role in the course of the disease. Our study provided more key elements in understanding the disparity of the clinical spectrum among regions.

Trends in Adult and Elderly Vaccination: Focus on Vaccination Practices in Tunisia and Morocco

Vaccine preventable diseases (VPDs) are a prevailing concern among the adult population, despite availability of vaccines. Unlike pediatric vaccination programs, adult vaccination programs lack the required reach, initiative, and awareness. Clinical studies and real-world data have proven that vaccines effectively reduce the disease burden of VPDs and increase life expectancy. In Tunisia and Morocco, the national immunization program (NIP) focuses more on pediatric vaccination and have limited vaccination programs for adults. However, some vaccination campaigns targeting adults are organized. For example, influenza vaccination campaigns prioritizing at risk adults which includes healthcare professionals, elderly, and patients with comorbidities. Women of childbearing age who have never been vaccinated or whose information is uncertain are recommended to receive tetanus vaccination. Tunisia NIP recommends rubella vaccine mainly for women of childbearing age, while in Morocco, national vaccination campaigns were organized for girls and women (up to 24 years of age) to eliminate rubella. Further, travelers from both countries are recommended to follow all requirements and recommendations in the travel destination. The objective of this manuscript is to provide an overview of the global disease burden of common VPDs including (but not limited to) meningococcal diseases, pneumococcal diseases, hepatitis, and influenza. The review also provides an overview of clinical data and guidelines/recommendations on adult vaccination practices, with special focus on Tunisia and Morocco. Some European and North American countries have concrete recommendations and strategies for adult vaccination to keep the VPDs in check. In Morocco and Tunisia, although, there are sporadic adult vaccination initiatives, the efforts still need upscaling and endorsements to boost vaccination awareness and uptake. There is a need to strengthen strategies in both countries to understand the disease burden and spread awareness. Additional studies are needed to generate economic evidence to support cost-effectiveness of vaccines. Integration of private and public healthcare systems may further improve vaccination uptake in adults.

Epidemiological patterns of Hepatitis A infection during the pre-vaccination Era: A population-based survey in Tunisia in 2015

BACKGROUND

In the 1980s, Tunisia was considered a country of high endemicity for Hepatitis A virus (HAV). Since 2000, an epidemiological shift has led to an increased incidence of symptomatic and severe forms of HAV infection.

OBJECTIVE

In 2015, we conducted a cross-sectional nationwide household-based HAV seroprevalence study in the total population regardless of age, sex, or geographical origin using a stratified sampling design in order to make an overview of the HAV epidemiological situation in Tunisia before vaccine implementation.

RESULTS

A total of 6322 individuals were enrolled. The HAV prevalence was 78.8%. The anti-HAV IgG seropositivity rate increases from 16% for ages 5-9 years to 45% for ages 10-14, 67% for ages 15-19, 87% for ages 20-24, and >90% for older age groups, which suggests an age at midpoint of population immunity (AMPI) in late adolescence. It was significantly higher in rural areas (p<10^-3) and varied significantly between and within regions (p<10^-4).

CONCLUSIONS

In this study, although the overall AMPI suggests intermediate endemicity, the regional AMPI varies from intermediate to very high endemicity profiles attributable to different socio-economic determinants and conditions of sanitation and hygiene. Also it provides insights for the best decisions in terms of vaccinations strategies.

Evaluating the cost-effectiveness of universal hepatitis B virus vaccination in Iran: a Markov model analysis

Vaccination is an essential way to prevent the transmission of hepatitis B virus (HBV). Various studies have been published on the cost-effectiveness of HBV vaccination, but since the results vary according to the target population and related health outcomes, this study examined the cost-effectiveness of the universal HBV vaccination in Iran. In this economic evaluation study, a decision tree with the Markov model was used to compare the universal HBV vaccination with a strategy of non-vaccination. Health states used in the model included healthy, chronic hepatitis B, compensated cirrhosis, decompensated cirrhosis, hepatocellular carcinoma, and death. Analyses were performed from a payer's perspective. Incremental cost-effectiveness ratio (ICER) per life-year gained, and quality-adjusted life-years (QALYs) gained were calculated at a 5% annual discount rate. The sensitivity analysis was conducted using Monte Carlo simulation. Analyses were performed using Microsoft Excel and TreeAge Pro 2011 software. In 2017, the estimated cost per dose for any HBV vaccine was $3.20 USD. The universal HBV vaccination was economically advantageous compared to non-vaccination, and the estimated cost of this program per life-year and QALY gained were $6,319 and negative (-) $1,183.85 USD, respectively. Given the uncertainty of all parameters, the model remained robust and reliable. In Iran, the universal HBV vaccination strategy for both health outcomes of QALY and life-years gained was cost-effective and advantageous. The vaccination strategy saved money, increased life years and improved quality of life. Therefore, it is recommended that this program continues to be provided.

Association of an IFN-γ variant with susceptibility to chronic hepatitis B by the enhancement of HBV DNA replication

Interferon gamma (IFN-γ) is a crucial cytokine in host immune response to hepatitis B virus (HBV) infection. This study aimed to determine whether a functional polymorphism +874T/A in IFN-γ gene linked to high and low producer phenotypes [IFN-γ (+874T^high → A^low)] may alter the outcomes of chronic HBV infection in Tunisian population. The +874T/A was analysed by ARMS-PCR method in the group of 200 patients chronically infected with HBV and 200 healthy controls. We observed that minor +874A allele, minor +874AA and +874TA genotypes were significantly more frequent in the chronic hepatitis B group in comparison to the control group [49 vs. 31%, P < 10^-4; 24 vs. 13%, P < 10^-4; 52 vs. 38%, P < 10^-4; respectively]. Besides, they were associated with susceptibility to hepatitis B infection [OR = 2.15, 3.87 and 2.84, respectively]. The minor +874A allele and +874AA genotype were statistically more representative in the sub-group of patients with high viral DNA load when compared with the sub-group of patients with low HBV DNA load [(57% vs. 43%, P = 0.003, OR = 1.79); (33% vs. 14%, P = 0.003, OR = 3.59), respectively]. Collectively, our study suggests an association between the IFN-γ +874T/A SNP and persistence of HBV by the enhancement of HBV DNA replication.

Strong association of functional polymorphism in IL-12B with susceptibility to chronic hepatitis B in Tunisia

BACKGROUND

The chronicity or clearance of hepatitis B virus (HBV) infection depends on viral and genetic variables. The immune response against HBV is thought to be responsible for viral persistence or clearance. Cytokines such as interleukin 1-2B (IL1-2B) involved in the T-helper 1 system are key mediators in the defence mechanisms against viral infection and play a role in the regulation of HBV clearance during infection. We aimed to examine whether the polymorphic variant TaqI polymorphism in the 3'-untranslated region (3'-UTR; rs3212227) suspected to modulate interleukin-levels of IL-12B has an influence on the risk of development of chronicity after HBV exposure.

METHODS

Genotyping was performed by the polymerase chain reaction-restriction fragment length polymorphism method for 236 patients with chronic hepatitis B (CHB) and 240 controls from different cities of Tunisia recruited in the Pasteur Institute of Tunisia between January 2017 and December 2018.

RESULTS

We found that the IL-12B polymorphism was associated with a significantly increased risk of CHB in patients (p = 1 × 10^-3 ; χ ²  = 10.31 and odds ratio [OR] = 2.14; 95% confidence interval [CI] = 1.30-3.52) when AC/CC variant genotypes were compared with the wild-type AA homozygote. Statistical significance was found when CHB-males were compared with CHB-females (p = 2 × 10^-7 ; χ ²  = 26.62 and p = 1 × 10^-3 ; χ ²  = 10.36, for genotypic and allelic frequencies, respectively). Also, CHB-patients carrying C-allele less than 50-years were at an increased risk of developing chronic HBV infection than patients more than 50-years (p = 6.1 × 10^-5 ; χ ²  = 16.07).

CONCLUSIONS

These results suggest that the C-allele would affect susceptibility to chronicity after HBV exposure in Tunisian patients especially for males less than 50-years. Age and sex have an influence on this polymorphism in CHB Tunisian patients.

Hepatitis B birth vaccination, cohort study, Tunisia 2000-2017

We aimed to compare the efficiency of the first dose of Hepatitis B (HB) vaccine: at Birth versus at 3 months and to evaluate the efficacy of HB vaccine. We conducted a cohort study in the governorate of Monastir. Vaccinated Cohort (VC) included populations receiving the first dose at 3 months (Protocol 1), and at birth (HepB-BD) (Protocol 2). First dose was followed by at least two doses. We collected, from January 2000 to December 2017, cases diagnosed by serological markers (hepatitis B surface antigen (HBsAg) and anti-HBc). We calculated Absolute Risk (AR) per 100,000 PY and the Relative risk reduction (RRR). Twenty-five cases were notified among VC and 1501 cases among not vaccinated cohort (NVC). Twenty-three cases were notified among the cohort receiving the first dose at 3 months and two cases in Protocol 2. The AR per 100,000 PY was 5.67 (CI95%: 3.36-7.99) in Protocol 1 and 0.11 (CI95%: 0.001-0.26) in Protocol 2. The RRR was 77% (95% CI: 66; 85) in Protocol 1 and 99.4% (95% CI: 97.8; 99.9) in Protocol 2. We identified 4 HB cases for children aged between 5 and 11 who benefited from protocol 1 (born between 2000 and 2006) and zero cases for children of the same age group benefiting from protocol 2 (born between 2011 and 2017). The annual number of HB has decreased from 112 in 2000 to 48 in 2017. We predicted 40 new cases of HB in 2030. HepB-BD was 99.4% effective at preventing HB. The continuity of HepB-BD worldwide would achieve WHO's goal of eliminating HB as a threat to health by 2050.

ABBREVIATIONS

AR: Absolute Risk; ARR: Absolute Risk Reduction; G1: Group1; G2: Group2; HB: Hepatitis B; HepB-BD: Hepatitis B Birth Dose; MENA: Middle East and North Africa; NNV: Number Needed to Vaccine; HIV: Human Immunodeficiency Virus; NVC: Not Vaccinated Cohort; PY: Person Year; RRR: Relative Risk Reduction; RR: Relative Risk; VC: Vaccinated Cohort; WHO: World Health Organization.

Interleukin IL-1B gene polymorphism in Tunisian patients with chronic hepatitis B infection: Association with replication levels

Approaches based on association studies have proven useful in identifying genetic predictors for many diseases, including susceptibility to chronic hepatitis B. In this study we were interested by the IL-1B genetic variants that have been involved in the immune response and we analyzed their role in the susceptibility to develop chronic hepatitis B in the Tunisian population. IL-1B is a potent proinflammatory cytokine that plays an important role in inflammation of the liver. Polymorphic gene IL-1 (-511, +3954) was analyzed in a total of 476 individuals: 236 patients with chronic hepatitis B from different cities of Tunisia recruited in Pasteur Institute between January 2017 and December 2018 and 240 controls. Genomic DNA was obtained using the standard salting-out method and genotyping was performed by polymerase chain reaction (PCR)-restriction fragment length polymorphism. For -511C>T polymorphism a significant association was found between patients and controls when comparing the genotypic (P = 0.007; χ²  = 9.74 and odds ratio [OR] = 0.60; confidence interval [CI] = 0.41-0.89) and allelic (P = 0.001; χ²  = 10.60) frequencies. When the viral load was taken into account a highly significant difference was found (P = 9 × 10^-4 ; χ²  = 10.89). For +3954C>T polymorphism a significant association was found between patients and controls when comparing genotypic (P = 0.0058; χ²  = 7.60 and OR = 1.67; CI = 1.14-2.46) and allelic (P = 0.0029; χ²  = 8.81) frequencies. T allele can be used as a strong marker for hepatitis B virus disease for both polymorphisms.