scholarly journals Efficacy of a Third BNT162b2 mRNA COVID-19 Vaccine Dose in Patients with CLL who Failed Standard Two-dose Vaccination

Blood ◽  
2021 ◽  
Author(s):  
Yair Herishanu ◽  
Galia Rahav ◽  
Shai Levi ◽  
Andrei Braester ◽  
Gilad Itchaki ◽  
...  

Patients with chronic lymphocytic leukemia (CLL) have an impaired antibody response to COVID-19 vaccination. Here, we evaluated the antibody response to a third BNT162b2 mRNA vaccine in patients with CLL/small lymphocytic lymphoma (SLL) who failed to achieve a humoral response after standard two-dose vaccination regimen. Anti-SARS-CoV-2S and neutralizing antibodies were measured 3 weeks after administration of the third dose. In 172 patients with CLL the antibody response rate was 23.8%. Response rate among actively treated patients (12.0%, n=12/100) was lower compared to treatment-naïve patients (40.0%, n=16/40; OR=4.9, 95% CI 1.9-12.9; p<0.001) and patients off-therapy (40.6%, n=13/32; OR=5.0, 95% CI 1.8-14.1; p<0.001), (p<0.001). In those actively treated with BTK inhibitors or venetoclax ± anti-CD20 antibody, response rates were extremely low (15.3%, n=9/59 and 7.7%, n=3/39, respectively). Only one of the 28 patients (3.6%) treated with anti-CD20 antibodies <12 months prior to vaccination responded. The anti-SARS-CoV-2S antibody levels correlated linearly with neutralizing antibody titers (r=0.732, p<0.001). In a multivariate analysis, the independent variables that were associated with response included lack of active therapy (OR=5.6, 95% CI 2.3-13.8; p<0.001) and serum IgA levels ≥80 mg/dL (OR=5.8, 95% CI 2.1-15.9; p<0.001) In conclusion, in patients with CLL/SLL who failed to achieve a humoral response after standard two-dose BNT162b2 mRNA vaccination regimen, close to a quarter responded to the third dose of vaccine. The antibody response rates were lower during active treatment and in patients with a recent exposure (<12 months prior to vaccination) to anti-CD20 therapy.

Haematologica ◽  
2021 ◽  
Author(s):  
Ohad Benjamini ◽  
Lior Rokach ◽  
Gilad Itchaki ◽  
Andrei Braester ◽  
Lev Shvidel ◽  
...  

Patients with chronic lymphocytic leukemia (CLL) have a suboptimal humoral response to vaccination. Recently, a BNT162b2 mRNA COVID-19 vaccine was introduced with a high efficacy of 95% in immunocompetent individuals. We investigated the safety and efficacy of BNT162b2 mRNA Covid-19 vaccine in patients with CLL from nine medical centers in Israel, In total 400 patients were included, of which 373 were found to be eligible for the analysis of antibody response. The vaccine appeared to be safe and only grade 1-2 adverse events were seen in 50% of the patients. Following the second dose, antibody response was detected in 43% of the cohort. In treatment- naïve patients 61% responded to the vaccine, while only 18%, 37% and 5% of patients with CLL ongoing, previously treated with BTKi, or recent anti CD20 antibody developed responses respectively. 62% and 14% of patients treated with BCL2 monotherapy or combined with anti CD20 developed immune response respectively. Neutralizing antibodies demonstrated high concordance with positive serologic response to spike (S) protein. Based on our results a simple scoring model including recent treatment with anti-CD20, age younger than 70 years, treatment naïve status, and normal IGG, IGA, IGM and hemoglobin levels. The sum of all the above parameters can serve as a possible estimate to predict whether a given CLL patient will develop sufficient antibodies. In conclusion, the vaccine was found to be safe in patients with CLL, but its efficacy is limited particularly in treated patients.


Chemotherapy ◽  
2021 ◽  
Author(s):  
Stefano Molica ◽  
Diana Giannarelli ◽  
Mirella Lentini ◽  
Daniela Zappala ◽  
Ada Mannella ◽  
...  

Background: Antibody response following SARS-CoV2 vaccination is somewhat defective in chronic lymphocytic leukemia (CLL). Moreover, the correlation between serologic response and status of cellular immunity has been poorly studied. Objective: This study was undertaken to assess humoral immune and cellular responses to the BNT162b2 messenger RNA (mRNA) COVID-19 vaccination in CLL. Methods: The presence of the spike antibodies was assessed at a median time of 14 days from the second vaccine dose of SARS-CoV2 in 70 CLL followed-up at a single institution. Results: The antibody response rate (RR) in CLL patients was 58.5%, compared to 100% of 57 healthy controls of the same sex and age (P< 0.0001). Patients treatment-naïve and those in sustained clinical remission after therapy had the highest RR (87.0% and 87.7%, respectively). In contrast, patients on therapy with a pathway inhibitor as monotherapy and those treated with an association of anti-CD20 antibody were unlikely to respond to the SARS-CoV-2 vaccine (52% and 10%, respectively). In multivariate analysis, early Rai stage (OR, 0.19 [0.05-0.79]; P=0.02) and no previous therapy (OR, 0.06[0.02-0.27]; P<0.0001) were found to be independent predictors of vaccination response. An increase in absolute NK cells (i.e., CD16/CD56 positive cells) in patients with a serological response was found following the second dose of vaccine (P=0.02). Conclusions: These results confirm that serological response to the BNT162b2 vaccine in patients with CLL is impaired. A third boosting vaccine dosage should be considered for these patients.


2021 ◽  
Vol 5 (16) ◽  
pp. 3053-3061
Author(s):  
C. Perry ◽  
E. Luttwak ◽  
R. Balaban ◽  
G. Shefer ◽  
M. M. Morales ◽  
...  

Abstract Patients diagnosed with B-cell non-Hodgkin lymphoma (B-NHL), particularly if recently treated with anti-CD20 antibodies, are at risk of severe COVID-19 disease. Because studies evaluating humoral response to COVID-19 vaccine in these patients are lacking, recommendations regarding vaccination strategy remain unclear. The humoral immune response to BNT162b2 messenger RNA (mRNA) COVID-19 vaccine was evaluated in patients with B-NHL who received 2 vaccine doses 21 days apart and compared with the response in healthy controls. Antibody titer, measured by the Elecsys Anti-SARS-CoV-2S assay, was evaluated 2 to 3 weeks after the second vaccine dose. Patients with B-NHL (n = 149), aggressive B-NHL (a-B-NHL; 47%), or indolent B-NHL (i-B-NHL; 53%) were evaluated. Twenty-eight (19%) were treatment naïve, 37% were actively treated with a rituximab/obinutuzumab (R/Obi)–based induction regimen or R/Obi maintenance, and 44% had last been treated with R/Obi &gt;6 months before vaccination. A seropositive response was achieved in 89%, 7.3%, and 66.7%, respectively, with response rates of 49% in patients with B-NHL vs 98.5% in 65 healthy controls (P &lt; .001). Multivariate analysis revealed that longer time since exposure to R/Obi and absolute lymphocyte count ≥0.9 × 103/μL predicted a positive serological response. Median time to achieve positive serology among anti-CD20 antibody-treated patients was longer in i-B-NHL vs a-B-NHL. The humoral response to BNT162b2 mRNA COVID-19 vaccine is impaired in patients with B-NHL who are undergoing R/Obi treatment. Longer time since exposure to R/Obi is associated with improved response rates to the COVID-19 vaccine. This study is registered at www.clinicaltrials.gov as #NCT04746092.


Blood ◽  
2021 ◽  
Author(s):  
Yair Herishanu ◽  
Irit Avivi ◽  
Anat Aharon ◽  
Gabi Shefer ◽  
Shai Levi ◽  
...  

Patients with chronic lymphocytic leukemia (CLL) have an increased risk for severe COVID-19 disease and mortality. The goal of this study (NCT04746092) was to determine the efficacy of COVID-19 vaccine in patients with CLL. We evaluated humoral immune responses to BNT162b2 mRNA COVID-19 vaccine in patients with CLL and compared responses with those obtained in age-matched healthy controls. Patients received two vaccine doses, 21 days apart, and antibody titers were measured using Elecsys® Anti-SARS-CoV-2S assay after administration of the second dose. In a total of 167 patients with CLL the antibody response rate was 39.5%. A comparison between 52 patients with CLL and 52 sex- and aged-matched healthy controls, revealed a significantly reduced response rate among patients (52% vs 100%, respectively; adjusted odds ratio=0.010, 95% CI 0.001-0.162; p&lt;0.001). Response rate was highest in patients who obtained clinical remission after treatment (79.2%), followed by 55.2% in treatment-naïve and 16% only in patients under treatment at the time of vaccination. In patients treated with either BTK inhibitors or venetoclax ± anti-CD20 antibody, response rates were considerably low (16.0% and 13.6%, respectively). None of the patients exposed to anti-CD20 antibodies &lt;12 months prior to vaccination responded. In a multivariate analysis, the independent predictors of response were younger age, females, lack of currently active treatment, IgG levels ≥550 mg/dL and IgM levels ≥40mg/dL. In conclusion, antibody-mediated response to BNT162b2 mRNA COVID-19 vaccine in patients with CLL is markedly impaired and affected by disease activity and treatment.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3791-3791
Author(s):  
Evangelos Terpos ◽  
Maria Gavriatopoulou ◽  
Ioannis Ntanasis-Stathopoulos ◽  
Alexandros Briasoulis ◽  
Sentiljana Gumeni ◽  
...  

Abstract Introduction: Recent data suggest a suboptimal antibody response to COVID-19 vaccination in patients with hematological malignancies. Herein, we evaluated the development of neutralizing antibodies (NAbs) against SARS-CoV-2 in patients with plasma cell neoplasms (PCNs) after vaccination with either the mRNA BNT162b2 or viral vector AZD1222 vaccine, up to 50 days post their first vaccine dose. Methods: This is an ongoing large prospective study (NCT04743388) evaluating the kinetics of anti-SARS-CoV-2 antibodies after COVID-19 vaccination in healthy subjects and in patients with hematological malignancies or solid tumors. Here we present the data on patients with PCNs in comparison to controls of similar age and gender, who were vaccinated during the same time period (January to March 2021) in Athens (Greece). Major exclusion criteria for both patients and controls included the presence of: (i) autoimmune disorder under immunosuppressive therapy or other active malignant disease; (ii) HIV or active hepatitis B and C infection, (iii) end-stage renal disease and (iv) prior diagnosis of COVID-19. Serum was collected on day 1 (D1; before the first vaccine dose), on day 22 (D22; before the second dose of the BNT162b2 or 3 weeks post the first AZD1222 dose) and on day 50 (D50; 4 weeks post second dose of the BNT162b2 or 7 weeks post the first AZD1222 dose). NAbs against SARS-CoV-2 were measured using an FDA approved-ELISA methodology (cPass™ SARS-CoV-2 NAbs Detection Kit, GenScript, Piscataway, NJ, USA). Results: We evaluated 382 patients with PCNs after vaccination with either the BNT162b2 or the AZD1222 vaccine. Patients with MM (n=213), WM (n=106), SMM (n=38) and MGUS (n=25) and 226 healthy controls were enrolled in the study. Of MM/SMM/MGUS patients, 215 (77.9%) were vaccinated with the BNT162b2 and 61 (22.1%) with the AZD1222 vaccine, while out of 106 WM patients 90 (84.9%) were vaccinated with the BNT162b2 and 16 (15.1%) with the AZD1222 vaccine. Vaccination with either two doses of the BNT162b2 or one dose of the AZD1222 vaccine led to lower production of NAbs against SARS-CoV-2 in patients compared with controls both on day 22 and on day 50 (P&lt;0.001 for all comparisons). After the first dose of the vaccine, on D22, the patient group had lower NAb titers compared with controls: the median NAb inhibition titer was 27% (IQR: 15.3-42%) for MM/SMM/MGUS versus 20.5% (IQR: 10-37%) for WM patients versus 38.7% (IQR: 22-54.3%) for controls (P&lt;0.001 for all comparisons). On D50 the median NAb inhibition titer was 62.8% (IQR: 26-88.9%) for MM/SMM/MGUS versus 36% (IQR: 18-78%) for WM patients versus 90% (IQR: 58-96.4%) for controls (P&lt;0.001 for all comparisons). 57.3% MM/SMM/MGUS, 42% WM patients and 81% controls developed NAb titers ≥50% (p&lt;0.001 for patients versus controls). Furthermore, MM patients showed an inferior NAb response compared with MGUS on day 22 (p=0.009) and on day 50 (p=0.003). Importantly, active treatment with either anti-CD38 monoclonal antibodies or belantamab mafodotin and lymphopenia at the time of vaccination were independent prognostic factors for suboptimal antibody response following vaccination in MM (p&lt;0.05). Disease-related immune dysregulation and therapy-related immunosuppression were involved in the low humoral response in patients with WM. Importantly, active treatment with either rituximab or Bruton's Tyrosine Kinase inhibitors (BTKIs) was proven as an independent prognostic factor for suboptimal antibody response following vaccination in WM (p&lt;0.05). Regarding adverse events, 33% and 31.6% patients reported mild reactions after the first and second dose of the BNT162b2 vaccine, respectively; 32.8% patients vaccinated with the first dose of AZD1222 also presented with local reactions. Conclusion: Patients with MM and WM have a low humoral response following SARS-CoV-2 vaccination, especially those who are under treatment with anti-CD38-, anti-BCMA-, anti-CD20- or BTKIs-based regimens. This result suggest that these patients have to continue the protective measures against SARS-CoV-2 as they are at high risk for COVID-19. Further studies on the kinetics of immune subpopulations following COVID-19 vaccination will elucidate the underlying immune landscape and determine the potential need for additional booster vaccine doses or protective administration of antibodies against SARS-CoV-2 in MM/WM patients with poor response after full vaccination. Disclosures Terpos: Janssen-Cilag: Consultancy, Honoraria, Research Funding; BMS: Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Genesis: Consultancy, Honoraria, Research Funding; GSK: Honoraria, Research Funding; Takeda: Consultancy, Honoraria, Research Funding; Sanofi: Consultancy, Honoraria, Research Funding; Novartis: Honoraria; Amgen: Consultancy, Honoraria, Research Funding. Gavriatopoulou: Janssen: Honoraria; Takeda: Honoraria; Sanofi: Honoraria; Karyopharm: Honoraria; Genesis: Honoraria; GSK: Honoraria; Amgen: Honoraria. Kastritis: Amgen: Honoraria, Research Funding; Janssen: Honoraria, Research Funding; Genesis: Honoraria; Takeda: Honoraria; Pfizer: Honoraria. Dimopoulos: Janssen: Honoraria; BeiGene: Honoraria; Takeda: Honoraria; Amgen: Honoraria; BMS: Honoraria.


Author(s):  
Cristina Bagacean ◽  
Rémi Letestu ◽  
Chadi Al-Nawakil ◽  
Ségolène Brichler ◽  
Vincent Lévy ◽  
...  

Immunocompromised individuals such as chronic lymphocytic leukemia (CLL) patients are at risk of impaired immune responses to vaccination. The objective of our study was to evaluate SARS-CoV-2-specific antibody responses in CLL patients, after the first, second and third doses of the BNT162b2 and mRNA-1273, and after a single dose for patients with confirmed prior COVID-19. Five hundred and thirty patients were included in the study. Patients received 2 doses at a 4-week interval, and a third dose if seronegative after the second dose. Response rate was 27% post-dose 1 and 52% post-dose 2. Post-dose 2 treatment-naïve patients had the highest response rate (72%) followed by patients previously treated by chemoimmunotherapy (60%). Among patients on therapy, patients on BTKi alone (22%) or in combination with anti-CD20 monoclonal antibodies or venetoclax (0%) had the poorer response rate whereas patients on venetoclax monotherapy achieved a significantly higher response rate (52%). A multivariate analysis identified as independent predictors of the absence of seroconversion: age &gt;65 years, ongoing CLL treatment and gamma-globulins ≤6g/L. Post-dose 2 seronegative patients had a global post-dose 3 response rate of 35%. This study provides an argument for the use of a third dose and for prophylactic SARS-CoV-2 neutralizing monoclonal antibodies.


Blood ◽  
2021 ◽  
Vol 138 (Supplement 1) ◽  
pp. 3724-3724
Author(s):  
Clare Sun ◽  
Erika M Gaglione ◽  
Lauren T Vaughn ◽  
Rui Mu ◽  
Chingiz Underbayev ◽  
...  

Abstract Humoral and cellular adaptive immunity likely contribute to protection against coronavirus disease 2019 (COVID-19). Neutralizing antibodies and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T cells have been detected in convalescent and immunized immunocompetent individuals. Chronic lymphocytic leukemia (CLL) and its treatment, particularly anti-CD20 monoclonal antibodies and Bruton tyrosine kinase inhibitors (BTKis), blunt the antibody response to vaccines. To understand the immunogenicity of COVID-19 vaccination in patients with CLL, assessment of the T-cell response is urgently needed. Between December 22, 2020 and May 7, 2021, 57 patients with CLL were immunized with either 2 doses of BNT162b2 (n = 30) or mRNA-1273 (n = 25) or 1 dose of Ad26.COV2.S (n = 2). Qualitative and semi-quantitative anti-spike antibodies were measured with serology tests authorized by the FDA under Emergency Use Authorization. A positive humoral response to vaccination was defined as the detection of anti-spike antibodies. Ultra-deep TCRß sequencing (Adaptive Biotechnologies) was performed on total peripheral blood mononuclear cells collected before and after vaccination. These data were analyzed in the immunoSEQ Analyzer. Differential abundance was calculated using the beta-binomial model and two-sided α=.05. SARS-CoV-2 spike-specific T cells were identified in the T-MAP COVID ImmuneCODE database. A positive cellular response to vaccination was defined as significant expansion of ≥1 spike-specific clonotype. Anti-spike antibodies were detected in 61% (35/57) of patients at a median (interquartile range, IQR) of 45 (30-56) days after the last dose of vaccine. The median (IQR) antibody titer was 19.1 U/mL (3.6-150.9) among 27 patients with humoral response. There were 4 patients with titers above the upper limit of quantification (&gt;250 U/mL) and 4 patients who had qualitative testing only. The rate of humoral response was 71% (15/21) in treatment naïve (TN) patients, 57% (16/28) in patients treated with BTKi, and 0% (0/4) in patients treated with venetoclax and anti-CD20 monoclonal antibody (mAb). Among 16 BTKi-treated patients with anti-spike antibodies, 2 interrupted BTKi during the vaccination period. One patient treated with venetoclax monotherapy and 3 previously treated patients had detectable anti-spike antibodies. The immediate prior therapies were acalabrutinib &gt;1 year before vaccination for 2 patients and chemoimmunotherapy &gt;8 years before vaccination for 1 patient. Vaccination with mRNA-1273 induced numerically higher titers compared to BNT162b2 (median 85.5 U/mL versus 11.0 U/mL; P=.1), but the rate of seroconversion was not significantly different (P=.4). No patients reported a history of SARS-CoV-2 infection and anti-nucleocapsid antibodies were negative in 100% (50/50) of patients tested. Circulating CD8 + T cells increased from a median (IQR) of 13.2% (7.8-18.8) at baseline to 14.3% (8.8-20.6) after vaccination (P=.015). CD3 + and CD4 + T cells did not significantly change. TCRß sequencing results are available in 7 patients (Table). The median (IQR) number of productive templates, which corresponds to the number of T cells sequenced in each sample, was 447,805 (377,738-503,097). Cellular response was observed in 57% (4/7) of patients. A total of 10 expanded spike-specific clonotypes were identified and ranged between 1 and 6 clonotypes per patient. The cumulative frequency of spike-specific clonotypes after vaccination ranged between 0.0036% and 1.55% per patient. None of these clonotypes were found at baseline despite the large number of productive templates generated in each sample. Spike-specific T cells were detected in 50% (2/4) of patients with anti-spike antibodies and 67% (2/3) of patients without seroconversion. In conclusion, patients with CLL have impaired humoral and cellular responses to COVID-19 vaccination. Seroconversion occurred less often in patients treated with BTKi than TN patients and was absent in patients treated with venetoclax and anti-CD20 mAb. Cellular responses were seen in the absence of humoral responses. TCRß sequencing is ongoing in additional patients. Updated data will be presented at the meeting. Figure 1 Figure 1. Disclosures Sun: Genmab: Research Funding. Wiestner: Merck: Research Funding; Nurix: Research Funding; Genmab: Research Funding; Verastem: Research Funding; Acerta Pharma: Research Funding; Pharmacyclics: Research Funding.


2021 ◽  
Vol 11 (1) ◽  
pp. 64
Author(s):  
Noa Berar-Yanay ◽  
Sarit Freiman ◽  
Maʹanit Shapira ◽  
Amer Saffoury ◽  
Ameer Elemy ◽  
...  

Background and objectives: The short-term reported antibody response to SARS-COV-2 vaccination in dialysis patients is high, with a seroconversion response rate up to 97%. Data on the long-term durability of this response are scarce. Our objective was to characterize the long-term anti-spike antibody level in dialysis patients. Design, setting, participants, and measurements: In an observational study, we measured SARS-COV-2 anti-spike antibody levels in dialysis patients who completed 2 doses of the BNT162b2 mRNA SAR S-COV-2 vaccine at 1, 3 and 6 months after the second vaccine dose. We compared the response to dialysis patients who were infected with COVD-19 and to a control group of healthcare-employees. Results: One hundred and forty-two dialysis patients who had been vaccinated (ages 64 ± 11.9 years, 61% male), 33 dialysis patients who had COVID-19 infection (ages 54 ± 14.3 years, 55% male) and 104 individuals in the control group (ages 50 ± 12.2 years, 44% male) were included. The response rate in the vaccinated dialysis patients was 94%, 78% and 73% at 1, 3 and 6 months after the second vaccine dose. In the COVID-19 infected dialysis group and in the control group, the response rate remained at 100% over 6 months. The percentage of change in antibody levels between one and 6 months was −66% in the vaccinated dialysis group, −28% in the control group (p < 0.001) and +48% in dialysis patients who had been infected with COVID-19 (p < 0.001). A non-responder status at 6 months was associated with a lower albumin level. No serious adverse events following vaccination were reported. In conclusion: the initially high response rate to the BNT162b2 vaccine in dialysis patients decreases rapidly. Our results indicate that an early booster (3rd) dose, at three months after the second dose, may be advised for this population to preserve the humoral immunity.


2021 ◽  
Author(s):  
Noa Eliakim Raz ◽  
Amos Stemmer ◽  
Yaara Leibovici-Weissman ◽  
Asaf Ness ◽  
Muhammad Awwad ◽  
...  

BACKGROUND Age and frailty are strong predictors of COVID-19 mortality. After the second BNT162b2 dose, immunity wanes faster in older (≥65 years) versus younger adults. The durability of response after the third vaccine is unclear. METHODS This prospective cohort study included healthcare workers/family members ≥60 years who received a third BNT162b2 dose. Blood samples were drawn immediately before (T0), 10-19 (T1), and 74-103 (T2) days after the third dose. Antispike IgG titers were determined using a commercial assay, seropositivity was defined as ≥50 AU/mL. Neutralizing antibody titers were determined at T2. Adverse events, COVID-19 infections, and clinical frailty scale (CFS) levels were documented. RESULTS The analysis included 97 participants (median age, 70 years [IQR, 66-74], 61% women, 58% CFS level 2). IgG titers, which increased significantly from T0 to T1 (medians, 440 AU/mL [IQR, 294-923] and 25,429 [14,203-36,114] AU/mL, respectively; P<0.001), decreased significantly by T2, but all remained seropositive (median, 8,306 AU/mL [IQR, 4595-14,701], P<0.001 vs T1). In a multivariable analysis, only time from the first vaccine was significantly associated with lower IgG levels at T2 (P=0.004). At T2, 60 patients were evaluated for neutralizing antibodies; all were seropositive (median, 1,294 antibody titer [IQR, 848-2,072]). Neutralizing antibody and antispike IgG levels were correlated (R=0.6, P<0.001). No major adverse events or COVID-19 infections were reported. CONCLUSIONS Antispike IgG and neutralizing antibodies levels remain adequate 3 months after the third BNT162b2 vaccine in healthy adults ≥60 years, although the decline in IgG is concerning. A third vaccine dose in this population should be top priority.


Author(s):  
C.R.B. Ferreira ◽  
C.F.T. Yoshida ◽  
L.A.C. Mercadante ◽  
D.F. Gomes ◽  
J.M. Oliveira ◽  
...  

A previous seroepidemiological study in the rural zone of Vargem Alta (ES) SouthEast of Brazil, showed a prevalence of up to 9% of hepatitis B surface antigen (HBsAg) in some areas. One hundred susceptible children aging 1 to 5 years old were selected and immunized with a recombinant DNA hepatitis B vaccine (Smith-Kline 20 mcg) using the 0-1-6 months vaccination schedule. Blood samples were collected at the time of the first vaccine dose (month 0) in order to confirm susceptible individuals and 1,3,6 and 8 months after the first dose , to evaluate the antibody response. Our results showed that two and five months after the second dose, 79% and 88% of children seroconverted respectively, reaching 97% after the third dose. The levels of anti-HBs were calculated in milli International Units/ml (mIU/ml) and demonstrated the markedly increase of protective levels of antibodies after the third dose. These data showed a good immunogenicity of the DNA recombinant hepatitis B vaccine when administered in children of endemic areas.


Sign in / Sign up

Export Citation Format

Share Document