Differing kinetics of anti-spike protein IgGs and neutralizing antibodies against SARS-CoV-2 after Comirnaty (BNT162b2) immunization.

Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) infection has had a serious worldwide impact on human health. On December 2020, an immunization campaign with a COVID-19 mRNA vaccine (Comirnaty-BNT162b2 Pfizer-BioNTech) was started in Italy, first targeting healthcare workers (HCWs). This study aims to investigate the antibodies that are response against SARS-CoV-2 vaccine. The kinetics and the persistence of both anti-S1/S2 IgGs and neutralizing antibodies (Nt-Abs) were investigated in 76 HCWs through a 4-month follow-up with multiple testing points starting at the first dose. Temporal analysis of SARS-CoV-2 Abs titre kinetics showed three different stages, with an initial slow growth in the anti-S1/S2 IgGs and Nt-Abs titres, corresponding to the first 4 weeks after the first dose of vaccine, followed by a second stage with peaks in titres, around 35 days after the first dose, and by a third stage (38 to 90-120 days after the first dose) showing a steady decrease in anti-S1/S2 IgGs while Nt-Abs are maintained at stable levels. Moreover, the levels of specific Nt-Abs to SARS-CoV-2 Spike protein are correlated to the anti-S1/S2 IgG titre (R-squared = 0.47; p < 0.001). The levels of specific Nt-Abs to SARS-CoV-2 Spike protein are correlated to the anti-S1/S2 IgG titre, although Nt-Abs could maintain a more stable titre over the time despite declining IgG Abs titre. This study highlights the kinetics and the persistence of Nt-Abs in HCWs vaccinated with Comirnaty (BNT162b2) Pfizer-BioNTech, and compared the Nt-Abs levels with anti-SARS-CoV-2 S1/S2 IgGs titres during a 4-month follow-up starting at the first dose of vaccine.

Bonura F ，De Grazia S ，Bonura C ，Sanfilippo GL ，Giammanco GM ，Amodio E ，Ferraro D ... -  《-》

Kinetics and Persistence of the Cellular and Humoral Immune Responses to BNT162b2 mRNA Vaccine in SARS-CoV-2-Naive and -Experienced Subjects: Impact of Booster Dose and Breakthrough Infections.

Understanding and measuring the individual level of immune protection and its persistence at both humoral and cellular levels after SARS-CoV-2 vaccination is mandatory for the management of the vaccination booster campaign. Our prospective study was designed to assess the immunogenicity of the BNT162b2 mRNA vaccine in triggering the cellular and humoral immune response in healthcare workers up to 12 months after the initial vaccination, with one additional boosting dose between 6 and 12 months. This prospective study enrolled 208 healthcare workers (HCWs) from the Liège University Hospital (CHU) of Liège in Belgium. Participants received two doses of BioNTech/Pfizer COVID-19 vaccine (BNT162b2) and a booster dose 6-12 months later. Fifty participants were SARS-CoV-2 experienced and 158 were naïve before the vaccination. Blood sampling was performed at the day of the first (T0) and second (T1) vaccine doses administration, then at 2 weeks (T2), 4 weeks (T3), 6 months (T4) and 12 months (T5) after the second dose. Between T4 and T5, participants also got the third boosting vaccine dose. A total of 1145 blood samples were collected. All samples were tested for the presence of anti-Spike antibodies, using the DiaSorin LIAISON SARS-CoV-2 Trimeric S IgG assay, and for anti-Nucleocapsid antibodies, using Elecsys anti-SARS-CoV-2 assay​​. Neutralizing antibodies against the SARS-CoV-2 Wuhan-like variant strain were quantified in all samples using a Vero E6 cell-based neutralization assay. Cell-mediated immune response was evaluated at T4 and T5 on 80 and 55 participants, respectively, by measuring the secretion of IFN-γ on peripheral blood lymphocytes using the QuantiFERON Human IFN-γ SARS-CoV-2, from Qiagen. We analyzed separately the naïve and experienced participants. We found that anti-spike antibodies and neutralization capacity levels were significantly higher in SARS-CoV-2 experienced HCWs compared to naïve HCWs at all time points analyzed except the one after boosting dose. Cellular immune response was also higher in experienced HCWs six months following vaccination. Besides the impact of SARS-CoV-2 infection history on immune response to BNT162b2 mRNA vaccine, we observed a significant negative association between age and persistence of humoral response. The booster dose induced an increase in humoral and cellular immune responses, particularly in naive individuals. Breakthrough infections resulted in higher cellular and humoral responses after the booster dose. Our data strengthen previous findings demonstrating that immunization through vaccination combined with natural infection is better than 2 vaccine doses immunization or natural infection alone. The benefit of the booster dose was greater in naive individuals. It may have implications for personalizing mRNA vaccination regimens used to prevent severe COVID-19 and reduce the impact of the pandemic on the healthcare system. More specifically, it may help prioritizing vaccination, including for the deployment of booster doses.

Desmecht S ，Tashkeev A ，El Moussaoui M ，Marechal N ，Perée H ，Tokunaga Y ，Fombellida-Lopez C ，Polese B ，Legrand C ，Wéry M ，Mni M ，Fouillien N ，Toussaint F ，Gillet L ，Bureau F ，Lutteri L ，Hayette MP ，Moutschen M ，Meuris C ，Vermeersch P ，Desmecht D ，Rahmouni S ，Darcis G ... -  《Frontiers in Immunology》

The role of neutralizing antibodies by sVNT after two doses of BNT162b2 mRNA vaccine in a cohort of Italian healthcare workers.

Evaluating anti-SARS-CoV-2 antibody levels is a current priority to drive immunization, as well as to predict when a vaccine booster dose may be required and for which priority groups. The aim of our study was to investigate the kinetics of anti-SARS-CoV-2 Spike S1 protein IgG (anti-S1 IgG) antibodies and neutralizing antibodies (NAbs) in an Italian cohort of healthcare workers (HCWs), following the Pfizer/BNT162b2 mRNA vaccine, over a period of up to six months after the second dose. We enrolled 57 HCWs, without clinical history of COVID-19 infection. Fluoroenzyme-immunoassay was used for the quantitative anti-S1 IgG antibodies at different time points T1 (one month), T3 (three months) and T6 (six months) following the second vaccine shot. Simultaneously, a commercial surrogate virus neutralization test (sVNT) was used for the determination of NAbs, expressed as inhibition percentage (% IH). Median values of anti-S1 IgG antibodies decreased from T1 (1,452 BAU/mL) to T6 (104 BAU/mL) with a percent variation of 92.8% while the sVNT showed a percent variation of 34.3% for the same time frame. The decline in anti-S1 IgG antibodies from T1 to T6 was not accompanied by a loss of the neutralizing capacity of antibodies. In fact at T6 a neutralization percentage <20% IH was observed only in 3.51% of HCWs. Our findings reveal that the decrease of anti-S1 IgG levels do not correspond in parallel to a decrease of NAbs over time, which highlights the necessity of using both assays to assess vaccination effectiveness.

Infantino M ，Manfredi M ，Stacchini L ，Cosma C ，Grossi V ，Lari B ，Russo E ，Amedei A ，Benucci M ，Veneziani F ，Casprini P ，Catalano CM ，Cirrincione G ，Bonaccorsi G ，Pompetti A ... -  《-》

Humoral immune response after different SARS-CoV-2 vaccination regimens.

The humoral immune response after primary immunisation with a SARS-CoV-2 vector vaccine (AstraZeneca AZD1222, ChAdOx1 nCoV-19, Vaxzevria) followed by an mRNA vaccine boost (Pfizer/BioNTech, BNT162b2; Moderna, m-1273) was examined and compared with the antibody response after homologous vaccination schemes (AZD1222/AZD1222 or BNT162b2/BNT162b2). Sera from 59 vaccinees were tested for anti-SARS-CoV-2 immunoglobulin G (IgG) and virus-neutralising antibodies (VNA) with three IgG assays based on (parts of) the SARS-CoV-2 spike (S)-protein as antigen, an IgG immunoblot (additionally contains the SARS-CoV-2 nucleoprotein (NP) as an antigen), a surrogate neutralisation test (sVNT), and a Vero-cell-based virus-neutralisation test (cVNT) with the B.1.1.7 variant of concern (VOC; alpha) as antigen. Investigation was done before and after heterologous (n = 30 and 42) or homologous booster vaccination (AZD1222/AZD1222, n = 8/9; BNT162b2/BNT162b2, n = 8/8). After the second immunisation, a subgroup of 26 age- and gender-matched sera (AZD1222/mRNA, n = 9; AZD1222/AZD1222, n = 9; BNT162b2/BNT162b2, n = 8) was also tested for VNA against VOC B.1.617.2 (delta) in the cVNT. The strength of IgG binding to separate SARS-CoV-2 antigens was measured by avidity. After the first vaccination, the prevalence of IgG directed against the (trimeric) SARS-CoV-2 S-protein and its receptor binding domain (RBD) varied from 55-95% (AZD1222) to 100% (BNT162b2), depending on the vaccine regimen and the SARS-CoV-2 antigen used. The booster vaccination resulted in 100% seroconversion and the occurrence of highly avid IgG, which is directed against the S-protein subunit 1 and the RBD, as well as VNA against VOC B.1.1.7, while anti-NP IgGs were not detected. The results of the three anti-SARS-CoV-2 IgG tests showed an excellent correlation to the VNA titres against this VOC. The agreement of cVNT and sVNT results was good. However, the sVNT seems to overestimate non- and weak B.1.1.7-neutralising titres. The anti-SARS-CoV-2 IgG concentrations and the B.1.1.7-neutralising titres were significantly higher after heterologous vaccination compared to the homologous AZD1222 scheme. If VOC B.1.617.2 was used as antigen, significantly lower VNA titres were measured in the cVNT, and three (33.3%) vector vaccine recipients had a VNA titre < 1:10. Heterologous SARS-CoV-2 vaccination leads to a strong antibody response with anti-SARS-CoV-2 IgG concentrations and VNA titres at a level comparable to that of a homologous BNT162b2 vaccination scheme. Irrespective of the chosen immunisation regime, highly avid IgG antibodies can be detected just 2 weeks after the second vaccine dose indicating the development of a robust humoral immunity. The reduction in the VNA titre against VOC B.1.617.2 observed in the subgroup of 26 individuals is remarkable and confirms the immune escape of the delta variant.

Rose R ，Neumann F ，Grobe O ，Lorentz T ，Fickenscher H ，Krumbholz A ... -  《BMC Medicine》

Poor Antibody Response to BioNTech/Pfizer Coronavirus Disease 2019 Vaccination in Severe Acute Respiratory Syndrome Coronavirus 2-Naive Residents of Nursing Homes.

Residents of nursing homes (NHs) are at high risk of coronavirus disease 2019 (COVID-19)-related disease and death and may respond poorly to vaccination because of old age and frequent comorbid conditions. Seventy-eight residents and 106 staff members, naive to infection or previously infected with severe acute respiratory syndrome coronavirus (SARS-CoV-2), were recruited in NHs in Belgium before immunization with 2 doses of 30 µg BNT162b2 messenger RNA (mRNA) vaccine at days 0 and 21. Binding antibodies (Abs) to SARS-CoV-2 receptor-binding domain (RBD), spike domains S1 and S2, RBD Ab avidity, and neutralizing Abs against SARS-CoV-2 wild type and B.1.351 were assessed at days 0, 21, 28, and 49. SARS-CoV-2-naive residents had lower Ab responses to BNT162b2 mRNA vaccination than naive staff. These poor responses involved lower levels of immunoglobulin (Ig) G to all spike domains, lower avidity of RBD IgG, and lower levels of Abs neutralizing the vaccine strain. No naive residents had detectable neutralizing Abs to the B.1.351 variant. In contrast, SARS-CoV-2-infected residents had high responses to mRNA vaccination, with Ab levels comparable to those in infected staff. Cluster analysis revealed that poor vaccine responders included not only naive residents but also naive staff, emphasizing the heterogeneity of responses to mRNA vaccination in the general population. The poor Ab responses to mRNA vaccination observed in infection-naive NH residents and in some naive staff members suggest suboptimal protection against breakthrough infection, especially with variants of concern. These data support the administration of a third dose of mRNA vaccine to further improve protection of NH residents against COVID-19.

Pannus P ，Neven KY ，De Craeye S ，Heyndrickx L ，Vande Kerckhove S ，Georges D ，Michiels J ，Francotte A ，Van Den Bulcke M ，Zrein M ，Van Gucht S ，Schmickler MN ，Verbrugghe M ，Matagne A ，Thomas I ，Dierick K ，Weiner JA ，Ackerman ME ，Goriely S ，Goossens ME ，Ariën KK ，Desombere I ，Marchant A ... -  《-》