Project description:BackgroundCOVID-19 pandemic has led to a loss of human life in millions and devastating socio-economic consequences worldwide. So far, vaccination is the most effective long-term strategy to control and prevent severe COVID-19 disease. The aim of the current study was to evaluate the humoral immune responses raised against the BNT162b2 vaccine in hospital healthcare workers.MethodsTotal number of 173 healthcare workers enrolled in the study. Their blood samples were collected in three different time intervals after the second SARS-CoV-2 vaccination and evaluated by the ELISA method to detect anti-spike protein IgM and IgG antibodies. The baseline characteristics of all participants were collected using questionnaires and were evaluated for finding any significant data.ResultsOur results demonstrated that the levels of antibodies were higher in the young group (21-30 years old) and also among male participants. Moreover, the highest levels of antibodies were detected from the group that received the third shot vaccination.ConclusionsOur results indicate that age, gender and third-dose vaccination can affect the levels of humoral immune responses against the BNT162b2 vaccine in healthcare workers.
Project description:BackgroundTo optimise the use of available SARS-CoV-2 vaccines, some advocate delaying second vaccination for individuals infected within six months. We studied whether post-vaccination immune response is equally potent in individuals infected over six months prior to vaccination.MethodsWe tested serum IgG binding to SARS-CoV-2 spike protein and neutralising capacity in 110 healthcare workers, before and after both BNT162b2 messenger RNA (mRNA) vaccinations. We compared outcomes between participants with more recent infection (n = 18, median two months, IQR 2-3), with infection-vaccination interval over six months (n = 19, median nine months, IQR 9-10), and to those not previously infected (n = 73).FindingsBoth recently and earlier infected participants showed comparable humoral immune responses after a single mRNA vaccination, while exceeding those of previously uninfected persons after two vaccinations with 2.5 fold (p = 0.003) and 3.4 fold (p < 0.001) for binding antibody levels, and 6.4 and 7.2 fold for neutralisation titres, respectively (both p < 0.001). The second vaccine dose yielded no further substantial improvement of the humoral response in the previously infected participants (0.97 fold, p = 0.92), while it was associated with a 4 fold increase in antibody binding levels and 18 fold increase in neutralisation titres in previously uninfected participants (both p < 0.001). Adjustment for potential confounding of sex and age did not affect these findings.InterpretationDelaying the second vaccination in individuals infected up to ten months prior may constitute a more efficient use of limited vaccine supplies.FundingNetherlands Organization for Health Research and Development ZonMw; Corona Research Fund Amsterdam UMC; Bill & Melinda Gates Foundation.
Project description:Despite strict guidelines for coronavirus disease 2019 (COVID-19), South Korea is facing its fourth pandemic wave. In this study, by using an automated electrochemiluminescence immunoassay assay, we tracked anti-spike protein receptor-binding domain (anti-S-RBD) antibody titer from the second dose to 2 weeks after the booster dose vaccination. After the second dose, 234 participants had their anti-S-RBD antibody titers decrease over time. We also showed the booster dose (the third dose) increased antibody titer by average 14 (min-max, 2-255)-fold higher compared to the second dose among the 211-booster group participants, therefore, the booster dose could be recommended for low responders to the second dose. Our findings showed a distinct humoral response after booster doses of BNT162b2 mRNA vaccines and may provide further evidence of booster vaccination efficacy. These data will also be helpful in vaccination policy decisions that determine the need for the booster dose.
Project description:The BNT162b2 vaccine, containing lipid nanoparticles-formulated mRNA encoding the full-length spike protein of SARS-CoV-2, has been employed to immunize health care workers in Italy, administered in two doses 21 days apart. In this study, we characterized the antibody response induced by the BNT162b2 vaccine in a group of health care workers, tested at baseline, after the first dose and after the booster. Thirty-nine subjects without previous exposure to SARS-CoV-2 were vaccinated with the BNT162b2 vaccine. IgM, IgG, and IgA anti-receptor binding domain (RBD) were tested by ELISA. Neutralizing antibodies were evaluated testing the inhibition of RBD binding to ACE2. Antibody avidity was measured by urea avidity ELISA. IgM anti-RBD are produced after the first dose of vaccine and persist after the booster. IgG and IgA anti-RBD antibodies are detected in high amounts in all the subjects after the first dose and further increase after the booster. A few subjects, already after the first dose, produce antibodies inhibiting RBD interaction with ACE2. After the booster, high levels of inhibitory antibodies are detected in all the subjects. Affinity maturation takes place with boosting and IgG anti-RBD avidity increases with the number of immunizations. A less pronounced increase is observed with IgA. These data indicate that the BNT162b2 vaccine can induce high levels of protective antibodies of high avidity in vaccinated subjects; both IgG and IgA anti-RBD antibodies are produced. Further studies are needed to evaluate antibody persistence over time.
Project description:The aim of this study was to characterize the antibody response induced by SARS-CoV-2 mRNA vaccines in a cohort of healthcare workers. A total of 2247 serum samples were analyzed using the Elecsys® Anti-SARS-CoV-2 S-test (Roche Diagnostics International Ltd., Rotkreuz, Switzerland). Sex, age, body mass index (BMI), arterial hypertension, smoking and time between infection and/or vaccination and serology were considered the confounding factors. Regarding the medians, subjects previously infected with SARS-CoV-2 who preserved their response to the nucleocapsid (N) protein showed higher humoral immunogenicity (BNT162b2: 6456.0 U/mL median; mRNA-1273: 2505.0 U/mL) compared with non-infected (BNT162b2: 867.0 U/mL; mRNA-1273: 2300.5 U/mL) and infected subjects with a lost response to N protein (BNT162b2: 2992.0 U/mL). After controlling for the confounders, a higher response was still observed for mRNA-1273 compared with BNT162b2 in uninfected individuals (FC = 2.35, p < 0.0001) but not in previously infected subjects (1.11 FC, p = 0.1862). The lowest levels of antibodies were detected in previously infected non-vaccinated individuals (39.4 U/mL). Clinical variables previously linked to poor prognoses regarding SARS-CoV-2 infection, such as age, BMI and arterial hypertension, were positively associated with increasing levels of anti-S protein antibody exclusively in infected subjects. The mRNA-1273 vaccine generated a higher antibody response to the S protein than BNT162b2 in non-infected subjects only.
Project description:ObjectivesThere are limited comparative immunologic durability data post COVID-19 vaccinations.MethodsApproximately 8.4 months after primary COVID-19 vaccination, 647 healthcare workers completed surveys about COVID-19 vaccinations/infections and blood draws. The groups included participants vaccinated with mRNA-1273 (n = 387), BNT162b2 (n = 212), or Ad26.COV2.S (n = 10) vaccines; unvaccinated participants (n = 10); and participants who received a booster dose (n = 28). The primary outcome was immunoglobin anti-spike titer. Secondary/tertiary outcomes included neutralizing antibodies (enzyme-linked immunosorbent assay-based pseudoneutralization) and vaccine effectiveness (VE). Antibody levels were compared using analysis of variance and linear regression.ResultsMean age was 49.7 and 75.3% of the participants were female. Baseline variables were balanced except for immunosuppression, previous COVID-19 infection, and post-primary vaccination time. Unadjusted median (interquartile range [IQR]) anti-spike titers (AU/ml) were 1539.5 (876.7-2626.7) for mRNA-1273, 751.2 (422.0-1381.5) for BNT162b2, 451.6 (103.0-2396.7) for Ad26.COV2.S, 113.4 (3.7-194.0) for unvaccinated participants, and 31898.8 (21347.1-45820.1) for participants administered with booster dose (mRNA-1273 vs BNT162b2, P <.001; mRNA-1273, BNT162b2, or boosted vs unvaccinated, P <.006; mRNA-1273, BNT162b2, Ad26.COV2.S, or unvaccinated vs boosted, P <.001). Unadjusted median (IQR) pseudoneutralization was as follows: 90.9% (80.1-95.0) for mRNA-1273, 77.2% (59.1-89.9) for BNT162b2, 57.9% (36.6-95.8) for Ad26.COV2.S, 40.1% (21.7-60.6) for unvaccinated, and 96.4% (96.1-96.6) for participants administered with booster dose (mRNA-1273 vs BNT162b2, P <.001; mRNA-1273, BNT162b2, or boosted vs unvaccinated, P <.028; mRNA-1273, BNT162b2, Ad26.COV2.S, or unvaccinated vs boosted, P <.001). VE was 87-89% for participants administered mRNA-1273 vaccine, BNT162b2 vaccine, and booster dose, and 33% for Ad26.COV2.S (none significantly different).ConclusionAntibody responses 8.4 months after primary vaccination were significantly higher with mRNA-1273 than those observed with BNT162b2.
Project description:Clinical trials and real-world evidence on COVID-19 vaccines have shown their effectiveness against severe disease and death but the durability of protection remains unknown. We analysed the humoral and T-cell immune responses in 110 healthcare workers (HCWs) vaccinated according to the manufacturer's recommended schedule of dose 2 three weeks after dose 1 from a prospective on-going cohort in early 2021, 3 and 6 months after full vaccination with the BNT162b2 mRNA vaccine. Anti-RBD IgG titres were lower in HCWs over 60 years old 3 months after the second dose (p=0.03) and declined in all the subjects between 3 and 6 months with a median percentage change of -58.5%, irrespective of age and baseline comorbidities. Specific T-cell response measured by IGRA declined over time by at least 42% (median) in 91 HCWs and increased by 33% (median) in 17 others. Six HCWs had a negative T-cell response at 6 months. Ongoing follow-up should provide correlates of long-term protection according to the different immune response profiles observed. COVIDIM study was registered under the number NCT04896788 on clinicaltrials.gov.
Project description:Assessing immune responses post-SARS-CoV-2 vaccination is crucial for optimizing vaccine strategies. This prospective study aims to evaluate immune responses and breakthrough infection in 235 infection-naïve healthcare workers up to 13-15 months after initial vaccination in two vaccine groups (108 BNT/BNT/BNT and 127 ChAd/ChAd/BNT). Immune responses were assessed using the interferon-gamma enzyme-linked immunospot (ELISPOT) assay, total immunoglobulin, and neutralizing activity through surrogate virus neutralization test at nine different time points. Both groups exhibited peak responses one to two months after the second or third dose, followed by gradual declines over six months. Notably, the ChAd group exhibited a gradual increase in ELISPOT results, but their antibody levels declined more rapidly after reaching peak response compared to the BNT group. Six months after the third dose, both groups had substantial cellular responses, with superior humoral responses in the BNT group (p < 0.05). As many as 55 breakthrough infection participants displayed higher neutralization activities against Omicron variants, but similar cellular responses compared to 127 infection-naïve individuals, suggesting cross-immunity. Distinct neutralization classifications (<30%, >80% inhibition) correlated with different ELISPOT results. Our study reveals diverse immune response patterns based on vaccine strategies and breakthrough infections, emphasizing the importance of understanding these dynamics for optimized vaccination decisions.
Project description:ObjectivesTo assess the humoral and cell-mediated response to severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) elicited by the mRNA BNT162b2 vaccine in SARS-CoV-2-experienced and -naive subjects against a reference strain and SARS-CoV-2 variants.MethodsThe humoral response (including neutralizing antibodies) and T-cell-mediated response elicited by BNT162b2 vaccine in 145 healthcare workers (both naive and positive for previous SARS-CoV-2 infection) were evaluated. In a subset of subjects, the effect of SARS-CoV-2 variants on antibody level and cell-mediated response was also investigated.ResultsOverall, 125/127 naive subjects (98.4%) developed both neutralizing antibodies and specific T cells after the second dose of vaccine. Moreover, the antibody and T-cell responses were effective against viral variants since SARS-CoV-2 NT Abs were still detectable in 55/68 (80.9%) and 25/29 (86.2%) naive subjects when sera were challenged against β and δ variants, respectively. T-cell response was less affected, with no significant difference in the frequency of responders (p 0.369). Of note, two doses of vaccine were able to elicit sustained neutralizing antibody activity against all the SARS-CoV-2 variants tested in SARS-CoV-2-experienced subjects.ConclusionsBNT162b2 vaccine elicited a sustained humoral and cell-mediated response in immunocompetent subjects after two-dose administration of the vaccine, and the response seemed to be less affected by SARS-CoV-2 variants, the only exceptions being the β and δ variants. Increased immunogenicity, also against SARS-CoV-2 variant strains, was observed in SARS-CoV-2-experienced subjects. These results suggest that triple exposure to SARS-CoV-2 antigens might be proposed as valuable strategy for vaccination campaigns.
Project description:Adverse reactions after vaccination with COVID-19 mRNA vaccines are common; however, the association between adverse reactions and humoral responses is uncertain. To determine whether humoral immune responses after BNT162b2 vaccine administration were associated with local and systemic adverse reactions, we conducted a prospective observational cohort study in a single tertiary referral center. Healthcare workers who received the first dose of BNT162b2 vaccine were recruited. SARS-CoV-2 anti-spike IgG antibody titers were measured three weeks after the second dose and information about adverse reactions after vaccination was collected. Among the 887 participants, 641 (72.3%) were women. The median age was 38 (range, 22-74) years. All but one showed anti-spike IgG levels well above the cutoff, with a median level of 13,600 arbitrary units/mL. Overall, 800 (92.2%) participants reported some reactions after the first dose and 822 (96.3%) after the second dose. Significantly more participants reported systemic reactions after the second dose than after the first dose (P < .01), and 625 (73.6%) reported that reactions were stronger after the second dose. Factors positively associated with elevation of anti-spike IgG levels were history of asthma (24% higher if present, P = .01) and stronger reactions after the second dose (19% higher if experienced, P = .02). The majority of participants showed good humoral responses and reported some adverse reactions after vaccination. Anti-spike IgG levels were significantly higher if adverse reactions after the second dose were stronger than those after the first dose. These findings may help inform current and future vaccine recipients.