Variation in the Humoral Immune Response Induced by the Administration of the BNT162b2 Pfizer/BioNTech Vaccine: A Systematic Review

IgG antibody levels against the SARS-CoV-2 spike protein in mother-child dyads after COVID-19 vaccination

PURPOSE

We aimed to assess IgG antibodies against the SARS-CoV-2 spike protein (anti-SARS-CoV-2 S IgG) in vaccinated mothers and their infants at delivery and 2-3 months of age.

METHODS

We conducted a prospective study on mothers who received at least one dose of the COVID-19 vaccine (Pfizer-BNT162b2, Moderna mRNA-1273, or Oxford-AstraZeneca ChAdOx1-S) during pregnancy and on their infants. The baseline was at the time of delivery (n = 93), and the end of follow-up was 2 to 3 months post-partum (n = 53). Serum anti-SARS-CoV-2 S IgG titers and ACE2 binding inhibition levels were quantified by immunoassays.

RESULTS

Mothers and infants had high anti-SARS-CoV-2 S IgG titers against the B.1 lineage at birth. However, while antibody titers were maintained at 2-3 months post-partum in mothers, they decreased significantly in infants (p < 0.001). Positive and significant correlations were found between anti-SARS-CoV-2 S IgG titers and ACE2-binding inhibition levels in mothers and infants at birth and 2-3 months post-partum (r > 0.8, p < 0.001). Anti-S antibodies were also quantified for the Omicron variant at 2-3 months post-partum. The antibody titers against Omicron were significantly lower in mothers and infants than those against B.1 (p < 0.001). Again, a positive correlation was observed for Omicron between IgG titers and ACE2-binding inhibition both in mothers (r = 0.818, p < 0.001) and infants (r = 0.386, p < 0.005). Previous SARS-CoV-2 infection and COVID-19 vaccination near delivery positively impacted anti-SARS-CoV-2 S IgG levels.

CONCLUSIONS

COVID-19 mRNA vaccines induce high anti-SARS-CoV-2 S titers in pregnant women, which can inhibit the binding of ACE2 to protein S and are efficiently transferred to the fetus. However, there was a rapid decrease in antibody levels at 2 to 3 months post-partum, particularly in infants.

Tip Lesion Most Frequent FSGS Variant Related to COVID-19 Vaccine: Two Case Reports and Literature Review

Large-scale COVID-19 vaccination has been one of the most effective strategies to control the spread of the SARS-CoV-2 virus. However, several cases of glomerular injury related to the COVID-19 vaccine have been described in the literature. We report two cases of a tip lesion variant of focal segmental glomerulosclerosis (FSGS), which presented with significant proteinuria and improved after immunosuppression. In our literature review, the tip lesion variant of FSGS is currently the most frequent variant associated with vaccination against COVID-19. Prognosis is favorable and without significant alterations in the tubulointerstitial or vascular compartments. Adverse effects of vaccines need to be recognized early and will help us to understand the immune and pathological mechanisms of kidney damage.

Assessment of the humoral response to the homologous Gam-COVID-Vac (Sputnik V) or heterologous Sputnik V/mRNA-1273 (Moderna) vaccination against SARS-CoV-2 in dialysis patients

BACKGROUND AND AIM

Dialysis patients are a high-risk population and have a reduced immune response to vaccination against SARS-CoV-2. The aim of this study was to assess the humoral response to homologous Gam-COVID-Vac (Sputnik V) and heterologous Sputnik V/mRNA-1273 (Moderna) vaccination in dialysis patients. The vaccination scheme depended on dose availability and the prioritization of risk populations as established by the Argentine Ministry of Health.

METHODS

Previous COVID-19 infection was determined in symptomatic patients. Binding IgG antibodies against the spike (S) receptor-binding domain (RBD) of SARS-CoV-2 (anti-S-RBD) concentration was assessed between 3 and 16 weeks after the boost dose. Anti-S-RBD antibodies were quantified using the Abbott Diagnostics SARS-CoV-2 IgG II Quant chemiluminescent microparticle immunoassay (CMIA) on an Architect i2000 SR and an Alinity I analyzer (Abbott Diagnostics, Abbott Park, Illinois, USA). To standardize the results to WHO binding antibody units (BAU), a correction factor for Abbott arbitrary units (AU) was applied where 1 BAU/mL equals 0.142 AU, as previously established by Abbott with the WHO international standard NIBSC 20-136. Following the manufacturer's recommendations, samples were considered reactive for anti-S-RBD when titers were above 50 AU/mL (7.2 BAU/mL). An 80% protective effect (PROT-80) against symptomatic SARS-CoV-2 infection was assumed when anti-S-RBD titers were 506 BAU/ml or higher. Charlson Comorbidity Index (CCI) score was classified as mild = 1-2, moderate = 3-4, and severe ≥ 5. Side effects were evaluated until day 7 by patients´ self-reported questionnaire.

RESULTS

One hundred seven participants were enrolled [n = 84 homologous (SpV/SpV), nn 23 heterologous (SpV/Mod)]. Median (IQR) age was 64 (50-75) years old and 79 (73.8%) were male. Additionally, 19 (22.6%) of the SpV/SpV and 4 (17.4%) of the SpV/Mod group had a prior confirmed SARS-CoV-2 infection (p = 0.589). In the overall population, 103 patients reached seroconversion (96.3%). Anti-S-RBD IgG median titers (IQR) were higher in the heterologous [1222 (288-5680) BAU/mL] than in the homologous scheme [447 (100-1551) BAU/mL], p = 0.022. In a linear model adjusted for age, gender, days from first vaccination to boost dose and days from the boost dose to the anti-S-RBD IgG determination, previous SARS-COV-2 infection (B: 2062.2; CI95: 1231.8-2892.6; p < 0.001), and SpV/Mod vaccination scheme (B: 1294.6; CI95: 435.58-2147.6; p = 0.003) were independently associated with anti-S-RBD levels. Finally, a higher frequency of adverse effects was associated with the heterologous scheme, although they were well tolerated by all individuals.

CONCLUSIONS

The present study provides evidence that the homologous SpV/SpV and heterologous SpV/Mod schemes showed good efficacy and safety in patients on chronic dialysis. These results could be useful for designing future vaccination strategies, especially aimed at this risk group.

Usefulness and Limitations of Anti-S IgG Assay in Detecting Previous SARS-CoV-2 Breakthrough Infection in Fully Vaccinated Healthcare Workers

Introduction: The anti-spike (S) IgG assay is the most widely used method to assess the immunological response to COVID-19 vaccination. Several studies showed that subjects with perivaccination infection have higher anti-S IgG titers. However, a cut-off has not yet been identified so far for distinguishing infected subjects after vaccination. This study thus evaluates the performance of the anti-S IgG assay in identifying subjects with breakthrough infections (BIs) and its potential usefulness for screening healthcare workers (HCWs). Methods: Out of 6400 HCWs of the University Hospital of Verona vaccinated with two doses of BNT162b2, 4462 never infected before subjects who had completed primary vaccination were tested for IgG anti-S 6 to 9 months after the second dose. Of these, 59 (1.3%) had a BI. The discriminant power of IgG anti-S in detecting previous breakthrough infection was tested by constructing receiver operating characteristic (ROC) curves. Results: The discriminant power for BI was rather good (area under the curve (AUC), 0.78) and increased with decreasing time elapsed between antibody titer assessment and previous SARS-CoV-2 infection. Accuracy (AUC) sensitivity increased from 0.78 (95% CI 0.70−0.85) for BI in the previous six months to 0.83 (95% CI 0.67−0.99) for those in the previous two months, and from 0.68 to 0.80, respectively. The specificity (0.86) and optimal cut-off (935 BAU/mL) remained unchanged. However, BI were rather rare (1.3%), so the positive predictive value (PPV) was low. Only 40 of the 664 HCWs with antibody titer > 935 BAU/mL had previously confirmed BI, yielding a PPV of only 6.0%. When adopting as cut-off the 90th percentile (1180 BAU/mL), PPV increased to 7.9% (35/441). Conclusions: The anti-S IgG assay displayed good sensitivity and specificity in discriminating subjects with BI, especially in recent periods. However, BIs were rare among HCWs, so that the anti-S IgG assay may have low PPV in this setting, thus limiting the usefulness of this test as a screening tool for HCWs. Further studies are needed to identify more effective markers of a previous infection in vaccinated subjects.

Immunity after COVID-19 Recovery and Vaccination: Similarities and Differences

The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is associated with a robust immune response. The development of systemic inflammation leads to a hyperinflammatory state due to cytokine release syndrome during severe COVID-19. The emergence of many new SARS-CoV-2 variants across the world deteriorates the protective antiviral immunity induced after infection or vaccination. The innate immune response to SARS-CoV-2 is crucial for determining the fate of COVID-19 symptomatology. T cell-mediated immunity is the main factor of the antiviral immune response; moreover, SARS-CoV-2 infection initiates a rapid B-cell response. In this paper, we present the current state of knowledge on immunity after COVID-19 infection and vaccination. We discuss the mechanisms of immune response to various types of vaccines (nucleoside-modified, adenovirus-vectored, inactivated virus vaccines and recombinant protein adjuvanted formulations). This includes specific aspects of vaccination in selected patient populations with altered immune activity (the elderly, children, pregnant women, solid organ transplant recipients, patients with systemic rheumatic diseases or malignancies). We also present diagnostic and research tools available to study the anti-SARS-CoV-2 cellular and humoral immune responses.