Correlation between anti-S IgG and neutralizing antibody titers against three live SARS-CoV-2 variants in BNT162b2 vaccine recipients

Different immunological responses following immunization with two mRNA vaccines

INTRODUCTION

Immunological responses were investigated following immunization with two mRNA vaccines: BNT162b2 and mRNA-1273.

METHODS

Neutralizing antibody (NAb) was assayed before, 2-4 weeks after, and 3 and 6 months after the primary immunization, and the same time-points after booster dose with 6- or 8-months interval. Whole-blood culture was stimulated with spike antigen, and cytokine production was assayed.

RESULTS

NAb was detected after primary immunization, NAb titers began to decrease three months after primary immunization with BNT162b2, lower than those after mRNA-1273, and elevated after booster immunization. The NAb level was 1/2 lower against δ variant, and 1/16 lower against omicron variant in comparison with that against α variant. Cytokine production following immunization with mRNA-1273 was maintained within three months at higher levels of Th1 (TNF-α), Th2 (IL-4 and IL-5), and inflammatory cytokines (IL-6 and IL-17) than that following immunization with BNT162b2, reflecting prominent levels of NAb following immunization with mRNA-1273. Cytokine production decreased six months after primary immunization in both vaccine recipients and was enhanced following booster doses. During the omicron outbreak, medical staff members in the outpatient office experienced asymptomatic infection, with a greater than 4-fold increase in NAb titers against omicron variant even after booster immunization. Asymptomatic infection enhanced the production of Th2 and inflammatory cytokines.

CONCLUSION

mRNA-1273 induced stronger NAb responses with wide-range cross-reactive antibodies against δ and omicron variants. mRNA-1273 induced higher levels of Th1, Th2, and inflammatory cytokines than BNT162b2 did, reflecting higher levels of NAb against variant strains.

Evaluation of Binding and Neutralizing Antibodies for Inactivated SARS-CoV-2 Vaccine Immunization

The circulating severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) variant presents an ongoing challenge for surveillance and detection. It is important to establish an assay for SARS-CoV-2 antibodies in vaccinated individuals. Numerous studies have demonstrated that binding antibodies (such as S-IgG and N-IgG) and neutralizing antibodies (Nabs) can be detected in vaccinated individuals. However, it is still unclear how to evaluate the consistency and correlation between binding antibodies and Nabs induced by inactivated SARS-CoV-2 vaccines. In this study, serum samples from humans, rhesus macaques, and hamsters immunized with inactivated SARS-CoV-2 vaccines were analyzed for S-IgG, N-IgG, and Nabs. The results showed that the titer and seroconversion rate of S-IgG were significantly higher than those of N-IgG. The correlation between S-IgG and Nabs was higher compared to that of N-IgG. Based on this analysis, we further investigated the titer thresholds of S-IgG and N-IgG in predicting the seroconversion of Nabs. According to the threshold, we can quickly determine the positive and negative effects of the SARS-CoV-2 variant neutralizing antibody in individuals. These findings suggest that the S-IgG antibody is a better supplement to and confirmation of SARS-CoV-2 vaccine immunization.

Neutralizing Antibody Response following a Third Dose of the mRNA-1273 Vaccine among Cancer Patients

Cancer patients are at an increased risk of morbidity and mortality from SARS-CoV-2 infection and have a decreased immune response to vaccination. We conducted a study measuring both the neutralizing and total antibodies in cancer patients following a third dose of the mRNA-1273 COVID-19 vaccine. Immune responses were measured with an enzyme-linked immunosorbent assay (ELISA) and neutralization assays. Kruskal-Wallis tests were used to evaluate the association between patient characteristics and neutralization geometric mean titers (GMTs), and paired t-tests were used to compare the GMTs between different timepoints. Spearman correlation coefficients were calculated to determine the correlation between total antibody and neutralization GMTs. Among 238 adults diagnosed with cancer, a third dose of mRNA-1273 resulted in a 37-fold increase in neutralization GMT 28 days post-vaccination and maintained a 14.6-fold increase at 6 months. Patients with solid tumors or lymphoid cancer had the highest and lowest neutralization GMTs, respectively, at both 28 days and 6 months post-dose 3. While total antibody GMTs in lymphoid patients continued to increase, other cancer types showed decreases in titers between 28 days and 6 months post-dose 3. A strong correlation (p < 0.001) was found between total antibody and neutralization GMTs. The third dose of mRNA-1273 was able to elicit a robust neutralizing antibody response in cancer patients, which remained for 6 months after administration. Lymphoid cancer patients can benefit most from this third dose, as it was shown to continue to increase total antibody GMTs 6 months after vaccination.

B and T Cell Responses to SARS-CoV-2 Vaccination in Kidney and Liver Transplant Recipients with and without Previous COVID-19

(1) Background: Vulnerable populations including transplant recipients are jeopardised by COVID-19. Herein, we report on B and T cell responses among liver and kidney organ recipients at our centre. (2) Methods: 23 liver and 45 kidney (14 thereof combined kidney/pancreas) transplanted patients were vaccinated with two doses of BNT162b2 followed by a booster dose of mRNA-1273 in 28 non-responders 4 months thereafter. Anti-SARS-CoV-2-Ig was measured by specific ELISA and virus neutralisation assay; T cell responses were measured by a spike protein-specific IFN-γ release assay. (3) Results: Compared to controls, B and T cell responses were weak in transplant recipients, particularly in those without prior exposure to SARS-CoV-2. Within this group, only 15% after the first and 58.3% after the second vaccination achieved seroconversion. A total of 14 out of 28 vaccination non-responders achieved a seroconversion after a third dose. Vaccination side effects were more frequent in healthy controls. The use of mycophenolate was associated with reduced anti-SARS-CoV-2-Ig production. (4) Conclusions: Our data confirm that vaccination responses are insufficient after standard vaccination in liver and kidney transplant recipients and are affected to a variable degree by specific immunosuppressants, particularly mycophenolate. Monitoring vaccination success and re-vaccinating those who are unresponsive seems prudent to achieve sufficient titres. Overall, prospective large-scale, multinational, multicentre studies or high-quality meta-analyses will be needed to generate personalised vaccination strategies in order to achieve protective immunity in high-risk, hard-to-immunize populations.

Humoral response against spike protein enhanced by fifth and sixth COVID-19 mRNA vaccine in the uninfected and infected subjects

Antibody obtained by the coronavirus disease-19 (COVID-19) mRNA vaccine declines over time, and additional vaccinations are offered. It is not clear how repeated vaccination affects humoral immunity in uninfected individuals. We analyzed immunoglobulin G for spike protein (S-IgG) titers in COVID-19 uninfected and infected individuals vaccinated up to six times. The geometric mean S-IgG titers were 575.9 AU/mL and 369.0 AU/mL in those who received 6 and 5 doses less than 180 days after the last vaccination in uninfected subjects. In the 180-360 days after the last vaccination, the geometric mean S-IgG titers were 237.9 AU/mL and 128.6 AU/mL in the uninfected subjects who underwent five-dose and four-dose groups, respectively. Multivariate analysis showed that S-IgG titer increased 1.261-fold with each additional dose of mRNA vaccine. The S-IgG titers were 2.039-fold higher in the COVID-infected subjects compared to uninfected subjects. The positivity rate of nucleocapsid antibodies, suggesting a history of COVID-19, decreased 82% and 30% of COVID-infected cases after 180 and 360 days of infection, respectively. This result suggested that repeated vaccination with the COVID-19 mRNA vaccine may increase antibody titer in uninfected subjects.

Serological analysis of severe acute respiratory syndrome coronavirus 2 infection in children with Kawasaki disease

Multisystem inflammatory syndrome in children (MIS-C) was reported as a severe complication of coronavirus disease 2019; an infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and was suggested to be associated with Kawasaki disease (KD) in terms of severe systemic inflammation and mucocutaneous symptoms. Because severe gastrointestinal symptoms and systemic shock are more frequently observed with MIS-C, patients with mild MIS-C might have been diagnosed with KD. In this study, titers of IgG antibodies against the SARS-CoV-2 S (S-IgG) and N proteins (N-IgG) were measured in 99 serum samples collected from patients with KD treated between January 2020 and December 2021 to evaluate the relationship between KD and SARS-CoV-2 infection. S-IgG were detected in only one patient out of 99 patients. This patient had coronavirus disease 2019 (COVID-19) 10 months before KD onset, and was unlikely MIS-C. According to characters of S-IgG and N-IgG, the patients was unlikely infected with SARS-CoV-2 just before the onset of KD. In addition to this study, the 26th Nationwide Survey and previous studies showed an association between KD and SARS-CoV-2 to be unlikely. In conclusion, SARS-CoV-2 infection was not observed in patients with KD until Delta predominance in Japan by the method of detecting SARS-CoV-2 IgG.

Assessment of mRNA Vaccine Immunogenicity in Solid Organ Transplant Recipients

Background and Objectives: Solid organ transplant (SOT) recipients have a higher risk of suffering from severe Coronavirus (COVID-19) compared to the general population. Studies have shown impaired immunogenicity of mRNA vaccines in this high-risk population; thus, SOT recipients have been prioritized globally for primary and booster doses. Materials and Methods: We analyzed 144 SOT recipients who had previously received two doses of BNT162b2 or mRNA1273 vaccine, and who were subsequently vaccinated with a booster dose of the mRNA1273 vaccine. Humoral and cellular immune responses were measured 1 and 3 months after the second dose, and 1 month after the third dose. Results: One month after the second dose, 33.6% (45/134) of patients displayed a positive antibody response with a median (25th, 75th) antibody titer of 9 (7, 161) AU/mL. Three months after the second dose, 41.8% (56/134) tested positive with a median (25th, 75th) antibody titer of 18 (7, 251) AU/mL. After the booster dose, the seropositivity rate increased to 69.4% (93/134), with a median (25th, 75th) titer of 966 (10, 8027) AU/mL. The specific SARS-CoV-2 T-cell response was assessed in 44 randomly selected recipients 3 months after the second dose, and 11.4% (5/44) of them had a positive response. Following the third dose, 42% (21/50) tested positive. Side effects after the third dose were mild, with pain at the injection site being the most frequent adverse effect, reported by 73.4% of the recipients. Conclusion: Our study shows a mild delayed increase in antibody titer, three months after primary vaccination compared to one month after. It also shows a robust augmentation of humoral and specific T-cell responses after the booster dose, as well as the safety and tolerability of the mRNA vaccines in SOT recipients.