New immune evasive variants of SARS-CoV-2 may increase infections and hospitalizations in risk groups, such as the elderly. In this study, we evaluated neutralizing antibodies against KP.3.1.1 and XEC, virus variants that were either widely distributed or on the rise globally in the fall of 2024, in sera from a cohort of seniors aged 68-82 years collected in April/May 2024. Neutralizing responses were low against both KP.3.1.1 and XEC, also in XBB.1.5 boosted individuals and people with recent break-through infections, supporting the recommendation of an updated COVID-19 vaccine booster in this age group.

Background As most people now have established hybrid immunity, the need for regular, updated SARS-CoV-2 vaccine boosters in patients with immune-mediated inflammatory diseases (IMIDs) is unclear. The study aim was to assess humoral and cellular immunogenicity of a fifth bivalent vaccine dose in patients with IMID on tumour necrosis factor inhibitors (TNFi). Methods In the longitudinal, observational Nor-vaC study, we assessed anti-spike and neutralising antibodies against Wuhan, Omicron BA.1 and BA.4, as well as frequency and polyfunctionality of responding T cells, following a fourth monovalent and a fifth bivalent (BA.1 or BA.4/5) vaccine dose in patients with or without hybrid immunity using TNFi. Findings Between December 17, 2021, and June 20, 2023, 456 infection-naive patients with IMIDs using TNFi received a fourth vaccine dose and were otherwise eligible for inclusion. A total of 373/456 (82%) received a fifth vaccine dose, of these 190/373 (51%) had hybrid immunity defined as having had COVID-19 between the fourth and fifth dose. In patients with hybrid immunity, the fifth dose did not induce improved humoral responses compared to infection, neither with BA.1 (median anti-spike antibody concentrations 23,244 IU/ml (IQR 15,138-45,233) vs 36,341 IU/ml (11,887-53,710), p = 0.52) nor BA.4/5 (31,693 IU/ml (15,176-54,186), p = 0.30). Comparison of neutralising antibodies yielded similar results. In infection-naive patients, a fifth BA.4/5 vaccine, but not the BA.1, induced slightly higher humoral responses (18,890 IU/ml (6494-50,211)) compared to the fourth dose (7304 IU/ml (3245-17,260), p < 0.0001). CD8 T cell responses remained stable following a fourth dose (median frequency of spike-specific cells 0.039% (IQR 0.010-0.14)), infection (0.058% (0.026-0.17)) and a fifth dose (0.058% (0.013-0.20). Interpretation In patients on TNFi with hybrid immunity, there was no immunological benefit of an updated fifth SARS-CoV-2 booster dose. Stable CD8 cellular responses following four doses indicate established protective immunity. Patients whose only risk factor is TNFi may in future follow vaccine recommendations for the general population. Copyright (c) 2024 The Authors. Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Abstract Heterogeneity in vaccine response, particularly in vulnerable populations like the elderly, represents a significant public health challenge. We conducted an in-depth examination of immune cell profiles before and after SARS-CoV-2 vaccination utilizing mass cytometry in a cohort of healthy Norwegian seniors (65–80 years). We have demonstrated that higher pre-vaccination frequencies of CD27+IgD- class-switched memory B cells and subsets of CD27-CD24+CD38+ transitional B cells were associated with a robust vaccine response. Post-vaccination, high responders exhibited increased frequencies of IFN-γ+CD4+ T cells with antigen recall and a concurrent decrease in CCR6(+) TH cell subset frequencies compared to low responders. The presence of a γδ T cell subset displaying polyfunctional cytokine responses was also associated with better vaccine response in the elderly. This in-depth profiling sheds light on inherent differences in immune cell frequencies and functions that may offer insights for targeted vaccination strategies in older populations.

Background: Patients with immune-mediated inflammatory diseases (IMIDs) on immunosuppressive therapies have attenuated humoral vaccine responses and are prone to more severe infections. Assessing the persistence of cellular and humoral immunity following repeated SARS-CoV-2 vaccine doses and infection is important to evaluate the need for booster vaccine doses. Objectives: To assess the cellular and humoral responses to 4th (original) and 5th (updated BA.1 or BA.4/5) SARS-CoV-2 vaccine doses and to COVID-19 following a 4th vaccine dose (hybrid immunity) in IMID patients on tumour necrosis factor inhibitors (TNFi). Methods: The ongoing observational Nor-vaC study includes IMID patients receiving multiple SARS-CoV-2 vaccines. In the present analyses, patients using TNFi who were eligible for a 5th vaccine dose and/or undergoing COVID-19 following a 4th vaccine dose, provided serum and peripheral blood mononuclear cells (PBMCs) 2-4 weeks and 4-11 months following infection, and before, 2-4 weeks, and 6 months after their 5th vaccination. CD4 and CD8 T cell responses to SARS-CoV-2 spike, nucleocapsid and membrane peptides, and also IgG anti-spike antibodies, were analysed. T cell responses were measured by flow cytometry (≥0.01% increase in responding CD4 or CD8 cells compared to unstimulated cells). Results: Between December 17th, 2021, and June 20th, 2023, 394 IMID patients (86 rheumatoid arthritis, 72 psoriatic arthritis, 97 spondyloarthritis, 86 Crohn’s disease, 53 ulcerative colitis) on TNFi received a 4th and 5th vaccine dose, and/or had COVID-19 following a 4th vaccine dose. (Table 1). Infection induced a small increase in spike-specific CD4 T cell responses in individuals who had already received a 4th dose (median (IQR) frequencies); four vaccine doses vs. hybrid immunity, 0.068% (0.034-0.16) vs. 0.11% (0.080-0.17), p=0.048). CD4 T cell responses after hybrid immunity waned over 4-11 months (0.035% (0.026-0.072), (hybrid immunity at 2-4 weeks vs. 4-11 months, p=0.0008). CD8 T cell responses following 4th vaccine dose (0.040 % (0.010-0.14) remained stable after infection (0.054% (0.025-0.17) p=0.57), and also in the next 4-11 months (0.038% (0.013-0.17) p=0.63). (Figure 1) A 5th vaccine dose restored CD4 T cell responses to the level seen 2-4 weeks after infection (0.089% (0.046-0.15), p=0.0093) compared with levels prior to 5th vaccine dose. CD8 T cell responses to a 5th vaccine dose did not significantly differ from those post-infection (0.057% (0.016-0.21) p=0.63). After infection, 32/36 (89%) patients had nucleocapsid-specific CD4 T cell responses and 23/36 (64%) had membrane-specific CD4 T cell responses. Similarly, 30/36 (83%) and 22/36 (61%) patients had nucleocapsid- and membrane-specific CD8 T cell responses. These responses decreased over time and were not boosted by vaccination. Patients with hybrid immunity had higher IgG anti-spike antibody levels than patients receiving only 4th dose (median 23159 IU/mL (IQR 14588-44529) vs 7242 (3220-17259) p<0.001. This humoral response waned prior to the 5th dose but increased following the 5th vaccine dose, median 9109 (3603-19839) vs. 31198 (13976-51224), p<0.001). Conclusion: CD8 T cell responses after four immunisations showed no significant benefit of further boosting, suggesting long-lived cellular responses that could be clinically protective. CD4 T cell and humoral responses wane following both four vaccinations and infection but are restored by vaccine boosters, indicating that also IMID patients with hybrid immunity could benefit from a booster vaccine to maintain high levels of circulating antibodies and spike-specific T cells.Table 1. Patient characteristics REFERENCES: NIL. Acknowledgements: We thank the patients who have participated in the Nor-vaC study. We are grateful for the time and effort they have invested in the project. We thank the patient representatives in the study group, Kristin Isabella Kirkengen Espe and Roger Thoresen. Many people have contributed to the study design and implementation of the study at The Norwegian Institute of Public Health, Akershus University Hospital, Diakonhjemmet hospital, and Oslo University Hospital. We thank all study personnel, laboratory personnel, and other staff at the clinical departments involved. Disclosure of Interests: Hilde S. Ørbo: None declared, Asia-Sophia Wolf: None declared, Taissa M. Kasahara: None declared, Kristin Hammersbøen Bjørlykke Janssen-Cilag, Ingrid Jyssum: None declared, Joe Sexton: None declared, Anne Therese Tveter: None declared, Guri Solum: None declared, Ingrid Fadum Kjønstad: None declared, Ingrid E. Christensen: None declared, Tore K. Kvien Grünenthal, Janssen, Sandoz, AbbVie, Gilead, Janssen, Novartis, Pfizer, Sandoz, UCB, AbbVie, BMS, Galapagos, Novartis, Pfizer, UCB, Grete B. Kro: None declared, Jørgen Jahnsen AbbVie/Abbott, Bristol-Myers, Squibb, Galapagos, Gilead, Janssen, Pfizer, Roche, Sandoz, Takeda, AbbVie/Abbott, Pfizer, Espen A. Haavardsholm Pfizer, UCB, Novartis, Abbvie, Pfizer, Eli Lilly, Ludvig A. Munthe Incyte, Janssen, Sella Aarrestad Provan: None declared, John Torgils Vaage: None declared, Kristin Kaasen Jørgensen Bristol-Myers Squibb, Roche, Gunnveig Grødeland Bayer, Sanofi, ThermoFisher, Pfizer, Vitusapotek, GSK, Siri Mjaaland: None declared, Silje Watterdal Syversen: None declared, Guro Løvik Goll AbbVie/Abbott, Galapagos, Pfizer, UCB.Figure 1CD4 T cells and anti-spike antibody levels following a 4th vaccine dose are boosted by infection (4th dose hybrid), with subsequent waning prior to a 5th vaccine dose before increasing after a 5th dose, in contrast to stable CD8 T-cell responses.

Background: The SARS-CoV-2 virus mutates continuously, posing challenges for patients with immune-mediated inflammatory diseases (IMIDs) on tumour necrosis factor inhibitors (TNFi). These patients often have diminished vaccine responses and are at a higher risk for severe infections. The efficacy of the recommended mono- and bivalent vaccine boosters in this patient population remains unclear. Objectives: To assess the neutralizing capacity and serologic responses to SARS-CoV-2 in TNFi-treated IMID patients, after receiving a monovalent 4th vaccine dose and a bivalent 5th vaccine dose, including those with hybrid immunity. Methods: These analyses from the ongoing observational Nor-vaC study included TNFi-treated IMID patients who received either a 5th vaccine dose or experienced SARS-CoV-2 infection following a 4th vaccine dose (hybrid immunity). Blood samples were collected 2-4 weeks after the 4th monovalent vaccine dose and after either subsequent COVID-19 or a 5th bivalent dose (BA.1 or BA.4/5). Neutralizing antibody titres against three viral variants (Wuhan (WT), Omicron BA.1, and Omicron BA.4), and IgG anti-spike antibody levels, were analysed. Group comparisons were performed with Mann Whitney U test, and Spearman correlation. Results: From Dec 17, 2021, to Jun 20, 2023, 371 IMID patients (86 rheumatoid arthritis, 72 psoriatic arthritis, 95 spondyloarthritis, 75 Crohn’s disease, 43 ulcerative colitis) on TNFi either received a 4th and a 5th vaccine dose or had a SARS-CoV-2 infection after the 4th vaccine dose. (Table 1) In infection-naïve patients, a 5th BA.4/5 vaccine increased neutralizing antibody titres against all viral variants tested (WT, BA.1 and BA.4), compared to post-4th dose levels (WT: median 640, IQR (80-1280) vs median 160, IQR (80-320) p=0.0096, BA.1: 160, IQR (40-640) vs 40, IQR (20-80) p=0.0014, BA.4: 640, IQR (80-2560) vs 80, IQR (30-160) p<0.0001)). (Figure 1A). Hybrid immunity increased neutralizing antibody titres against all tested variants compared to a 4th vaccine dose (WT: median 640, IQR (320-2560), p<0.0001), BA1: median 640, IQR (320-800), p<0.0001, BA4: median 1280, IQR (640-2560) p<0.0001) and 5th vaccine dose with BA.1 (WT: median 160, IQR (80-640) p<0.0001, BA1: median 80, IQR (40-640) p<0.0001, BA4: median 120, IQR (35-640) p<0.0001). In infection naïve patients, a 5th BA.4/5 vaccine gave higher neutralizing antibody responses against BA.4 than a 5th BA.1 vaccine (p=0.006) and comparable to that after hybrid immunity (p=0.21). There was no difference in neutralizing antibody titres between patients receiving TNFi in mono- or combination therapy (WT: p=0.64, BA.1: p=0.77, BA.4/5: p=0.83). Neutralizing antibody titres against WT variant were strongly correlated to anti-spike antibody levels following all immunisations (4th monovalent (r=0.86, p<0.0001), the 5th BA.1 (r=0.72, p<0.0001), the 5th BA.4/5 (r=0.49, p<0.0001)), as well as the hybrid group (r=0.44, p<0.0001). Patients with hybrid immunity had a higher median anti-spike antibody level (23159 IU/ml, IQR (14587-44529), than did infection naïve patients receiving the 5th dose BA.1 vaccine (10095 IU/ml (IQR 5261-30.095), p=0.0009), but comparable to levels after a BA.4/5 vaccine dose (17450 IU/ml (IQR 6705-57767), p=0.16). (Figure 1B) Conclusion: Our findings highlight the effectiveness of updated, targeted vaccines as booster doses for IMID patients on TNFi, in terms of neutralizing and anti-spike antibody responses. Infection-naïve patients benefit most from updated vaccines, providing a humoral response comparable to that following SARS-CoV-2 infection.Table 1. Patient characteristics. REFERENCES: NIL. Acknowledgements: We thank the patients who have participated in the Nor-vaC study. We are grateful for the time and effort they have invested in the project. We thank the patient representatives in the study group, Kristin Isabella Kirkengen Espe and Roger Thoresen. Many people have contributed to the study design and implementation of the study at The Norwegian Institute of Public Health, Akershus University Hospital, Diakonhjemmet hospital, and Oslo University Hospital. We thank all study personnel, laboratory personnel, and other staff at the clinical departments involved. Disclosure of Interests: Hilde S. Ørbo: None declared, Taissa M. Kasahara: None declared, Asia-Sophia Wolf: None declared, Kristin Hammersbøen Bjørlykke Janssen-Cilag, Joe Sexton: None declared, Ingrid Jyssum: None declared, Anne Therese Tveter: None declared, Guri Solum: None declared, Ingrid Fadum Kjønstad: None declared, Andreas Lind: None declared, Veselka P. Dimova-Svetoslavova: None declared, Tore K. Kvien Grünenthal, Janssen, Sandoz, AbbVie, Gilead, Janssen, Novartis, Pfizer, Sandoz, UCB, AbbVie, BMS, Galapagos, Novartis, Pfizer, UCB, Jørgen Jahnsen AbbVie/Abbott, Bristol-Myers, Squibb, Galapagos, Gilead, Janssen, Pfizer, Roche, Sandoz, Takeda, AbbVie/Abbott, Pfizer, Espen A. Haavardsholm Pfizer, UCB, Novartis, Abbvie, Pfizer, Eli Lilly, Ludvig A. Munthe Incyte, Janssen, Sella Aarrestad Provan: None declared, John Torgils Vaage: None declared, Siri Mjaaland: None declared, Kristin Kaasen Jørgensen Bristol-Myers Squibb, Roche, Gunnveig Grødeland Bayer, Sanofi, ThermoFisher, Pfizer, Vitusapotek, GSK, Silje Watterdal Syversen: None declared, Guro Løvik Goll AbbVie/Abbott, Galapagos, Pfizer, UCB.Figure 1Serology results showing neutralizing antibody titers (A) and anti-spike antibody levels (B) in infection-naïve patients following a 4th monovalent and a 5th bivalent vaccine dose (BA.1 vs BA4/5), as well as in patients with hybrid immunity post-infection following a 4th vaccine dose (4th hybrid). Statistical significance is denoted by * (p<0.05), **, (p<0.01), *** (p<0.001), and **** (p<0.0001).

BACKGROUND:Understanding cellular responses to SARS-CoV-2 immunisations is important for informing vaccine recommendations in patients with inflammatory bowel disease (IBD) and other vulnerable patients on immunosuppressive therapies. This study investigated the magnitude and quality of T cell responses after multiple SARS-CoV-2 vaccine doses and COVID-19 breakthrough infection. METHODS:This prospective, observational study included patients with IBD and arthritis on tumour necrosis factor inhibitors (TNFi) receiving up to four SARS-CoV-2 vaccine doses. T cell responses to SARS-CoV-2 peptides were measured by flow cytometry before and 2-4 weeks after vaccinations and breakthrough infection to assess the frequency and polyfunctionality of responding cells, along with receptor-binding domain (anti-RBD) antibodies. FINDINGS:Between March 2, 2021, and December 20, 2022, 143 patients (118 IBD, 25 arthritis) and 73 healthy controls were included. In patients with either IBD or arthritis, humoral immunity was attenuated compared to healthy controls (median anti-RBD levels 3391 vs. 6280 BAU/ml, p = 0.008) after three SARS-CoV-2 vaccine doses. Patients with IBD had comparable quantities (median CD4 0.11% vs. 0.11%, p = 0.26, CD8 0.031% vs. 0.047%, p = 0.33) and quality (polyfunctionality score: 0.403 vs. 0.371, p = 0.39; 0.105 vs. 0.101, p = 0.87) of spike-specific T cells to healthy controls. Patients with arthritis had lower frequencies but comparable quality of responding T cells to controls. Breakthrough infection increased spike-specific CD8 T cell quality and T cell responses against non-spike peptides. INTERPRETATION:Patients with IBD on TNFi have T cell responses comparable to healthy controls despite attenuated humoral responses following three vaccine doses. Repeated vaccination and breakthrough infection increased the quality of T cell responses. Our study adds evidence that, in the absence of other risk factors, this group may in future be able to follow the general recommendations for COVID-19 vaccines. FUNDING:South-Eastern Norway Regional Health Authority, Coalition for Epidemic Preparedness Innovations (CEPI), Norwegian Institute of Public Health, Akershus University Hospital, Diakonhjemmet Hospital.

Abstract Background Understanding T cell responses to SARS-CoV-2 immunisation in patients on immunosuppressive treatment is important for future vaccine recommendations. Our aim was to investigate the magnitude and quality of T cell responses following repeated SARS-CoV-2 vaccine doses and COVID-19 (breakthrough infections). Methods In this prospective, observational study of responses to SARS-CoV-2 vaccines (Nor-vaC)1, patients with inflammatory bowel disease (IBD) on TNF inhibitor (TNFi) therapy receiving up to four SARS-CoV-2 vaccine doses, and healthy controls receiving three vaccine doses were included. CD4 and CD8 T cell responses to SARS-CoV-2 peptides were measured by flow cytometry before and 2-4 weeks following vaccination and breakthrough infection. Antibodies to the receptor binding domain (RBD) of the Wuhan-Hu-1 and BA.1 (omicron) strains were measured. Results Between March 2, 2021, and December 20, 2022, 118 IBD patients, and 21 healthy controls were included in the study (Table). Following three vaccine doses, the humoral immune response was attenuated in IBD patients compared to healthy controls (median 3954 BAU/ml vs. 6280 BAU/ml, p=0.008). However, both the percentage of spike-specific T cells (CD4 median 0.11% vs. 0.10%, p=0.259, CD8 0.030% vs. 0.046%, p=0,333) and T cell polyfunctionality scores (a measure of quality of vaccine response) (CD4 median 0.403 vs. 0.371, p=0.386, CD8 0.105 vs. 0.101, p=0.871), showed comparable quality in IBD patients and controls following three doses. CD4 T cell responses increased rapidly and plateaued after two vaccine doses whereas CD8 T cell responses continued to improve up to four vaccine doses (Figure). Breakthrough infection in patients following the third or fourth vaccine dose increased CD8 polyfunctionality and generated broad CD4 and CD8 T cell responses against non-spike peptides. There was no difference in T cell responses between patients using TNFi mono- and combo therapy after primary vaccination (three vaccine doses) (p=0.648). Conclusion Despite attenuated antibody responses, IBD patients on TNFi treatment demonstrated T cell responses comparable to healthy controls following three SARS-CoV-2 vaccine doses. Repeated vaccination and breakthrough infection increased the quality and breadth of T cell responses, reaching a plateau. Distinguishing between CD4 and CD8 immune compartments and dynamics of activation after SARS-CoV-2 immunisation may provide nuanced understanding of protective cellular responses The study results indicate that IBD patients on TNFi treatment may in future follow the same recommendations for further SARS-CoV-2 vaccines as the general population. 1Clinialtrials.gov NCT04798625

Background T cells are critical for control of viral infection with SARS-CoV-2, but knowledge is lacking on cellular immune responses following repeated vaccination and breakthrough infection in immunosuppressed patients. Objectives To examine longitudinal T cell responses across diagnoses, following vaccine series and COVID-19 in patients on tumor necrosis factor inhibitors (TNFi). Methods The prospective, observational Nor-vaC study included patients with arthritis (spondyloarthritis, rheumatoid arthritis, psoriatic arthritis) or inflammatory bowel disease (IBD) (ulcerative colitis, Crohns disease) on immunosuppressive therapies [1]. Here, we included patients on TNFi mono- or combination therapy immunised with up to four SARS-CoV-2 vaccine doses with or without breakthrough infection, collecting peripheral blood mononuclear cells (PBMCs) 2-4 weeks after each immunisation. Samples were incubated with SARS-CoV-2 spike, nucleocapside or membrane peptides. The percentage of responding T cells was measured by flow cytometry (2) (≥0.01% increase in responding CD4 cells, ≥0.001% increase in responding CD8 cells, compared to baseline). Results Between February 2021 and December 2022, 144 patients on TNFi (monotherapy n=86 (60%), combination with methotrexate or azathioprine n=58 (40%)) were included (median age 48 years [IQR 33-57]; 51% women) (Table 1).The proportions of arthritis vs IBD patients with CD4 responses after 2 vaccine doses were 75% (12/16 patients) vs 86% (25/29), and after 3 doses 83% (10/12) vs 93% (28/30). In total, 80% (4/5) of arthritis patients showed further increases in CD4 responses after a 4th vaccine dose.Conversely, 81% (13/16) of arthritis patients vs. 55% (16/29) of IBD patients had CD8 T cell responses after two doses, and 67% (8/12) vs. 62% (18/29) after three doses. A 3rd and 4th dose induced higher CD8 responses compared to the previous dose in 55% (6/11) and 100% (5/5) of arthritis patients.Arthritis patients had lower T cell responses than IBD patients after the 3rd dose; median CD4 response 0.024% [IQR 0.009-0.036] vs 0.098% [IQR 0.040-0.182], p=0.0004; median CD8 response 0.003% [IQR 0.001-0.016] vs 0.044% [IQR 0.009-0.140], p=0.0032 (Figure 1). This difference remained robust after adjusting for age and sex, p<0.001, but was no longer detected after the 4th vaccine dose.Breakthrough infection elicited increased T cell responses across all diagnoses to spike (p<0.0001), and to nucleocapsid (p=0.002) and membrane proteins (p=0.001) compared to unstimulated T cells. Also, Spike-specific T cell responses increased compared to the 3rd dose (median CD4 T cell response 0.18% vs. 0.06%, p=0.003; CD8 T cell response 0.08% vs. 0.01%, p<0.0001), but to a lesser extent compared to the 4th dose (median CD4 response 0.18% vs. 0.12%, p=0.05; CD8 response 0.08% vs. 0.05%, p=0.26).There were no differences in cellular response between patients on TNFi mono- or combination therapy (p=0.93). Conclusion Patients on TNFi show improved cellular responses following each immunisation, with infection generating a strong and broad T cell response. Arthritis patients had significantly lower CD4+ responses compared to IBD patients after three vaccine doses, but with no difference after the 4th dose. These results support giving a 4th vaccine dose to TNFi-treated patients, with particular benefit for arthritis patients. References [1]Syversen S.W et al Arthritis Rheumatol. 2022[2]Kared H et al Nature Communications. 2022 Acknowledgements We thank the patients and health-care workers who have participated in the Norwegian study of vaccine response to COVID-19. We thank the patient representatives in the study group, Kristin Isabella Kirkengen Espe and Roger Thoresen. We thank all study personnel, laboratory personnel, and other staff involved at the departments involved, particularly Synnøve Aure, Margareth Sveinsson, May Britt Solem, Elisabeth Røssum-Haaland, and Kjetil Bergsmark. Disclosure of Interests Hilde Ørbo: None declared, Asia -Sophia F. M. Wolf: None declared, Kristin Hammersbøen Bjørlykke Speakers bureau: Speakers bureaus for Janssen-Cilag, Sarah Josefsson: None declared, Guri Solum: None declared, Ingrid Fadum Kjønstad: None declared, Ingrid Jyssum: None declared, Ingrid E. Christensen: None declared, Anne Therese Tveter: None declared, Joseph Sexton: None declared, Grete B. Kro: None declared, Gunnveig Grodeland Speakers bureau: Bayer, Sanofi, ThermoFisher, Consultant of: AstraZeneca, Tore K. Kvien Speakers bureau: Amgen, Celltrion, Egis, Evapharma, Ewopharma, Hikma, Oktal, Sandoz, Sanofi, Consultant of: AbbVie, Biogen, Celltrion, Eli Lilly, Gilead, Mylan, Novartis, Pfizer, Sandoz, Sanofi, Grant/research support from: AbbVie, Amgen, BMS MSD, Novartis, Pfizer, UCB, Jørgen Jahnsen Speakers bureau: AbbVie/Abbott, Bristol-Myers, Squibb, Galapagos, Gilead, Janssen, Pfizer, Roche, Sandoz, Takeda, Consultant of: AbbVie/Abbott, Pfizer, Bristol-Myers Squibb, Galapagos, Gilead, Janssen, Roche, Sandoz, Takeda, Grant/research support from: Boehringer-Ingelheim, John Torgils Vaage: None declared, Espen A Haavardsholm Speakers bureau: Pfizer, UCB, Consultant of: AbbVie, Boehringer-Ingelheim, Eli Lilly, Gilead, Sella Aarrestad Provan: None declared, Hassen Kared: None declared, Ludvig A. Munthe Speakers bureau: Novartis, Cellgene, Kristin Kaasen Jørgensen Speakers bureau: Bristol-Myers Squibb, Roche, Silje Watterdal Syversen: None declared, Siri Mjaaland: None declared, Guro Løvik Goll Speakers bureau: AbbVie/Abbott, Galapagos, Pfizer, UCB, Consultant of: AbbVie/Abbott, Galapagos, Pfizer, UCB.Table 1Number of patients providing T cells after vaccine doses and after COVID-19.Disease, n (%)Patients totala (n=144)2 vaccines (n=49)3 vaccines (n=86)4 vaccines (n=44)Hybrid immunityb (n=62)Arthritis25 (17)17 (35)19 (22)5 (11)5 (8)IBD119 (83)32 (65)67 (78)39 (89)57 (92)aSampled at minimum one timepointb3 or 4 vaccine doses, followed by COVID-19Figure 1CD4 and CD8 T-cell responses to the 3rd (V3) and 4th (V4) vaccine doses/ three vaccine doses and COVID-19 infection in arthritis and IBD patients measured by TNFα+ CD40L+ (% of CD4+) and IFNγ+ TNFα+ (% of CD8+).

BACKGROUND:Older age is associated with poorer outcomes to COVID-19 infection. The Norwegian Institute of Public Health established a longitudinal cohort of adults aged 65-80 years to study the effects of the COVID-19 pandemic. Here we describe the characteristics of the cohort in general, and specifically the immune responses at baseline and after primary and booster vaccination in a subset of longitudinal blood samples, and the epidemiological factors affecting these responses. METHODS:4551 participants were recruited, with humoral (n=299) and cellular (n=90) responses measured before vaccination and after two and three vaccine doses. Information on general health, infections, and vaccinations were obtained from questionnaires and national health registries. FINDINGS:Half of the participants had a chronic condition. 849 (18·7%) of 4551 were prefrail and 184 (4%) of 4551 were frail. 483 (10·6%) of 4551 had general activity limitations (scored with the Global Activity Limitation Index). After dose two, 295 (98·7%) of 299 participants were seropositive for anti-receptor binding domain IgG, and 210 (100%) of 210 participants after dose three. Spike-specific CD4 and CD8 T cell responses showed high heterogeneity after vaccination and responded to the alpha (B.1.1.7), delta (B.1.617.2), and omicron (B.1.1.529 or BA.1) variants of concern. Cellular responses to seasonal coronaviruses increased after SARS-CoV-2 vaccination. Heterologous prime boosting with mRNA vaccines was associated with the highest antibody (p=0·019) and CD4 T cell responses (p=0·003), and hypertension with lower antibody levels after three doses (p=0·04). INTERPRETATION:Most older adults, including those with comorbidities, generated good serological and cellular responses after two vaccine doses. Responses further improved after three doses, particularly after heterologous boosting. Vaccination also generated cross-reactive T cells against variants of concern and seasonal coronaviruses. Frailty was not associated with impaired immune responses, but hypertension might indicate reduced responsiveness to vaccines even after three doses. Individual differences identified through longitudinal sampling enables better prediction of the variability of vaccine responses, which can help guide future policy on the need for subsequent doses and their timing. FUNDING:Norwegian Institute of Public Health, Norwegian Ministry of Health, Research Council of Norway, and Coalition for Epidemic Preparedness Innovations.

Immune responses in people with multiple sclerosis (pwMS) receiving disease-modifying therapies (DMTs) have been of significant interest throughout the COVID-19 pandemic. Lymphocyte-targeting immunotherapies, including anti-CD20 treatments and sphingosine-1-phosphate receptor (S1PR) modulators, attenuate Ab responses after vaccination. Evaluation of cellular responses after vaccination, therefore, is of particular importance in these populations. In this study, we used flow cytometry to analyze CD4 and CD8 T cell functional responses to SARS-CoV-2 spike peptides in healthy control study participants and pwMS receiving 5 different DMTs. Although pwMS receiving rituximab and fingolimod therapies had low Ab responses after both 2 and 3 vaccine doses, T cell responses in pwMS taking rituximab were preserved after a third vaccination, even when an additional dose of rituximab was administered between vaccine doses 2 and 3. PwMS taking fingolimod had low detectable T cell responses in peripheral blood. CD4 and CD8 T cell responses to SARS-CoV-2 variants of concern Delta and Omicron were lower than to the ancestral Wuhan-Hu-1 variant. Our results indicate the importance of assessing both cellular and humoral responses after vaccination and suggest that, even in the absence of robust Ab responses, vaccination can generate immune responses in pwMS.

The SARS-CoV-2 Omicron variant has more than 15 mutations in the receptor binding domain of the Spike protein enabling increased transmissibility and viral escape from antibodies in vaccinated individuals. It is unclear how vaccine immunity protects against Omicron infection. Here we show that vaccinated participants at a super-spreader event have robust recall response of humoral and pre-existing cellular immunity induced by the vaccines, and an emergent de novo T cell response to non-Spike antigens. Individuals with Omicron SARS-CoV-2 breakthrough infections have significantly increased activated SARS-CoV-2 wild type Spike-specific cytotoxic T cells, activated follicular helper (TFH) cells, functional T cell responses, boosted humoral responses, and rapid release of Spike and RBD-specific IgG+ B cell plasmablasts and memory B cells into circulation. Omicron breakthrough infection affords significantly increased de novo memory T cell responses to non-Spike viral antigens. Concerted T and B cell responses may provide durable and broad immunity.

The new SARS-CoV-2 variant of concern (VOC) Omicron has more than 30 mutations in the receptor binding domain (RBD) of the Spike protein enabling viral escape from antibodies in vaccinated individuals and increased transmissibility. It is unclear how vaccine immunity protects against Omicron infection. Here we show that vaccinated participants at a superspreader event had robust recall response of humoral and pre-existing cellular immunity induced by the vaccines, and an emergent de novo T cell response to non-Spike antigens. We compared cases from a Christmas party where 81 of 110 (74%) developed Omicron breakthrough COVID-19, with Delta breakthrough cases and vaccinated non-infected controls. Omicron cases had significantly increased activated SARS-CoV-2 wild type Spike-specific (vaccine) cytotoxic T cells, activated follicular helper (TFH) cells, functional T cell responses, boosted humoral responses, activated anti-Spike plasmablasts and anti-RBD memory B cells compared to controls. Omicron cases had significantly increased de novo memory T cell responses to non-Spike viral antigens compared to Delta breakthrough cases demonstrating development of broad immunity. The rapid release of Spike and RBD-specific IgG+ B cell plasmablasts and memory B cells into circulation suggested affinity maturation of antibodies and that concerted T and B cell immunity may provide durable broad immunity.

Pneumococcal conjugate vaccine (PCV) efficacy is lower for noninvasive pneumonia than invasive disease. In this study, participants were immunized with 13-valent PCV (PCV13) or hepatitis A vaccine (control). Bronchoalveolar lavage samples were taken between 2 and 6 months and serum at 4 and 7 weeks postvaccination. In the lung, anti-capsular immunoglobulin G (IgG) levels were higher in the PCV13 group compared to controls for all serotypes, except 3 and 6B. Systemically, IgG levels were elevated in the PCV13 group at 4 weeks for all serotypes, except serotype 3. IgG in bronchoalveolar lavage and serum positively correlated for nearly all serotypes. PCV13 shows poor immunogenicity to serotype 3, implying lack of protective efficacy. Clinical Trials Registration. ISRCTN 45340436.

Childhood pneumococcal conjugate vaccine (PCV) protects against invasive pneumococcal disease caused by vaccine-serotype (VT) Streptococcus pneumoniae by generating opsonophagocytic anti-capsular antibodies, but how vaccination protects against and reduces VT carriage is less well understood. Using serological samples from PCV-vaccinated Malawian individuals and a UK human challenge model, we explored whether antibody quality (IgG subclass, opsonophagocytic killing, and avidity) is associated with protection from carriage. Following experimental challenge of adults with S. pneumoniae serotype 6B, 3/21 PCV13-vaccinees were colonised with pneumococcus compared to 12/24 hepatitis A-vaccinated controls; PCV13-vaccination induced serotype-specific IgG, IgG1, and IgG2, and strong opsonophagocytic responses. However, there was no clear relationship between antibody quality and protection from carriage or carriage intensity after vaccination. Similarly, among PCV13-vaccinated Malawian infants there was no relationship between serotype-specific antibody titre or quality and carriage through exposure to circulating serotypes. Although opsonophagocytic responses were low in infants, antibody titre and avidity to circulating serotypes 19F and 6A were maintained or increased with age. These data suggest a complex relationship between antibody-mediated immunity and pneumococcal carriage, and that PCV13-driven antibody quality may mature with age and exposure.

Natural killer cells employ a diverse arsenal of effector mechanisms to target intracellular pathogens. Differentiation of natural killer (NK) cell activation pathways occurs along a continuum from reliance on innate pro-inflammatory cytokines and stress-induced host ligands through to interaction with signals derived from acquired immune responses. Importantly, the degree of functional differentiation of the NK cell lineage influences the magnitude and specificity of interactions with host cells infected with viruses, bacteria, fungi, and parasites. Individual humans possess a vast diversity of distinct NK cell clones, each with the capacity to vary along this functional differentiation pathway, which - when combined - results in unique individual responses to different infections. Here we summarize these NK cell differentiation events, review evidence for direct interaction of malaria-infected host cells with NK cells and assess how innate inflammatory signals induced by malaria parasite-associated molecular patterns influence the indirect activation and function of NK cells. Finally, we discuss evidence that anti-malarial immunity develops in parallel with advancing NK differentiation, coincident with a loss of reliance on inflammatory signals, and a refined capacity of NK cells to target malaria parasites more precisely, particularly through antibody-dependent mechanisms.

Innate lymphoid cell (ILC) lineages mirror those of CD4+ T helper cell subsets, producing type 1, 2 and 3 cytokines respectively. Studies in adult human populations have shown contributions of non-cytotoxic ILC to immune regulation or pathogenesis in a wide range of diseases and have prompted investigations of potential functional redundancy between ILC and T helper cell compartments in neonates and children. To investigate the potential for ILC to contribute to immune responses across the human lifespan, we examined the numbers and frequencies of peripheral blood ILC subsets in a cohort of Gambians aged between 5 and 73 years of age. ILC2 were the most abundant peripheral blood ILC subset in this Gambian cohort, while ILC1 were the rarest at all ages. Moreover, the frequency of ILC1s (as a proportion of all lymphocytes) was remarkably stable over the life course whereas ILC3 cell frequencies and absolute numbers declined steadily across the life course and ILC2 frequencies and absolute numbers declined from childhood until the age of approx. 30 years of age. Age-related reductions in ILC2 cell numbers appeared to be partially offset by increasing numbers of total and GATA3+ central memory (CD45RA-CCR7+) CD4+ T cells, although there was also a gradual decline in numbers of total and GATA3+ effector memory (CD45RA-CCR7-) CD4+ T cells. Despite reduced overall abundance of ILC2 cells, we observed a coincident increase in the proportion of CD117+ ILC2, indicating potential for age-related adaptation of these cells in childhood and early adulthood. While both CD117+ and CD117- ILC2 cells produced IL-13, these responses occurred predominantly within CD117- cells. Furthermore, comparison of ILC frequencies between aged-matched Gambian and UK young adults (25–29 years) revealed an overall higher proportion of ILC1 and ILC2, but not ILC3 in Gambians. Thus, these data indicate ongoing age-related changes in ILC2 cells throughout life, which retain the capacity to differentiate into potent type 2 cytokine producing cells, consistent with an ongoing role in immune modulation.