Mass cytometry reveals cellular correlates of immune response heterogeneity to SARS-CoV-2 vaccination in the elderly (preprint)

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 TH17 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 comprehensive analysis sheds light on inherent differences in immune cell frequencies and functions that should offer insights for targeted vaccination strategies in older populations.

T cell responses to SARS-CoV-2 vaccination in people with multiple sclerosis differ between disease-modifying therapies (preprint)

Immune responses in people with multiple sclerosis (pwMS) on 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 antibody responses after vaccination. Evaluation of cellular responses after vaccination is therefore of particular importance in these populations. In this study, we analysed CD4 and CD8 T cell functional responses to SARS-CoV-2 spike peptides in healthy controls and pwMS on five different DMTs by flow cytometry. Although pwMS on anti-CD20 and S1PR therapies had low antibody responses after both 2 and 3 vaccine doses, T cell responses in pwMS on anti-CD20 therapies were preserved after third vaccination, even when additional anti-CD20 treatment was administered between vaccine doses 2 and 3. PwMS taking S1PR modulators 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 antibody responses vaccination can generate immune responses in pwMS.

Titers of antibodies the receptor-binding domain (RBD) of ancestral SARS-CoV-2 are predictive for levels of neutralizing antibodies to multiple variants (preprint)

Diagnostic assays currently used to monitor the efficacy of COVID-19 vaccines measure levels of antibodies to the receptor-binding domain of ancestral SARS-CoV-2 (RBDwt). However, the predictive value for protection against new variants of concern (VOCs) has not been firmly established. Here, we used bead-based arrays and flow cytometry to measure binding of antibodies to spike proteins and receptor-binding domains (RBDs) from VOCs in 12,000 sera. Effects of sera on RBD-ACE2 interactions were measured as a proxy for neutralizing antibodies. The samples were obtained from healthy individuals or patients on immunosuppressive therapy who had received two to four doses of COVID-19 vaccines and from COVID-19 convalescents. The results show that anti-RBDwt titers correlate with the levels of binding- and neutralizing antibodies against the Alpha, Beta, Gamma, Delta, Epsilon and Omicron variants. The benefit of multiplexed analysis lies in the ability to measure a wide range of anti-RBD titers using a single dilution of serum for each assay. The reactivity patterns also yield an internal reference for neutralizing activity and binding antibody units per milliliter (BAU/ml). Results obtained with sera from vaccinated healthy individuals and patients confirmed and extended results from previous studies on time-dependent waning of antibody levels and effects of immunosuppressive agents. We conclude that anti-RBDwt titers correlate with levels of neutralizing antibodies against VOCs and propose that our method may be implemented to enhance the precision and throughput of immunomonitoring.

Multiplexed measurement of binding- and neutralizing antibodies to SARS-CoV-2 variants in 12.000 post-vaccine sera (preprint)

Diagnostic assays currently used to monitor the efficacy of COVID-19 vaccines measure levels of antibodies to the receptor-binding domain of ancestral SARS-CoV-2 (RBDwt). However, the predictive value for protection against new variants of concern (VOCs) has not been firmly established. Here, we used bead-based arrays and flow cytometry to measure binding of antibodies to spike proteins and receptor-binding domains (RBDs) from VOCs in 12,000 sera. Effects of sera on RBD-ACE2 interactions were measured as a proxy for neutralizing antibodies. The samples were obtained from healthy individuals or patients on immunosuppressive therapy who had received two to four doses of COVID-19 vaccines and from COVID-19 convalescents. The results show that anti-RBDwt titers correlate with the levels of binding- and neutralizing antibodies against the Alpha, Beta, Gamma, Delta, Epsilon and Omicron variants. The benefit of multiplexed analysis lies in the ability to measure a wide range of anti-RBD titers using a single dilution of serum for each assay. The reactivity patterns also yield an internal reference for neutralizing activity and binding antibody units per milliliter (BAU/ml). Results obtained with sera from vaccinated healthy individuals and patients confirmed and extended results from previous studies on time-dependent waning of antibody levels and effects of immunosuppressive agents. We conclude that anti-RBDwt titers correlate with levels of neutralizing antibodies against VOCs and propose that our method may be implemented to enhance the precision and throughput of immunomonitoring.

Immunity in Omicron SARS-CoV-2 breakthrough COVID-19 in vaccinated adults (preprint)

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.

Efficacy and safety of a third SARS-CoV-2 vaccination in multiple sclerosis vaccine non-responders (preprint)

Importance: Vaccination against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) to protect against coronavirus disease of 2019 (COVID-19) is recommended for patients with multiple sclerosis (pwMS). However, approximately 80% of all pwMS treated with anti-CD20 therapy (rituximab, ocrelizumab) or fingolimod have low or absent humoral immunity after vaccination with two doses of SARS-CoV-2 mRNA vaccines. The efficacy and safety of a third vaccine dose in this group is largely unknown. Objective: To characterize the humoral immunogenicity and the safety of a third dose of mRNA-COVID-19 vaccine in anti-CD20- or fingolimod-treated pwMS with low or absent humoral immunity (i.e., anti-SARS-CoV-2 IgG <70 arbitrary units (AU) and <5 AU, respectively) after two vaccinations. Design, setting and participants: 130 anti-CD20- or fingolimod-treated pwMS with low or absent humoral immunity despite full vaccination against SARS-CoV-2, received a third dose of SARS-CoV-2 mRNA vaccine. Humoral immunity (i.e., antibody response against SARS-CoV-2) and the frequency and characteristics of side-effects were analyzed in all participants. Exposures: A third vaccine dose against SARS-CoV-2 with BNT162b2- or mRNA-1273-COVID-19 vaccine. Main outcomes and measures: Patient- and treatment-specific variables were acquired using a digital questionnaire, the Norwegian Immunization Registry and hospital journals. Humoral immunity was assessed by measuring SARS-CoV-2 SPIKE receptor-binding domain (RBD) IgG response. Low/absent humoral immunity was assumed in cases of AU<70 after anti-SPIKE protein-based serology 3-5 weeks after revaccination. Results: A third dose of SARS-CoV-2 mRNA vaccine increased anti-SARS-CoV-2 SPIKE RBD IgG levels significantly. The proportion of patients with assumed protective humoral immunity (anti-SARS-CoV-2 SPIKE RBD IgG > 70 AU) were 25% among patients using anti-CD20 therapy and 7% among those treated with fingolimod. No adverse events were registered during the study period. Conclusion and relevance: A third dose of mRNA-COVID-19 vaccine was associated with significantly increased levels of anti-SARS-CoV-2 SPIKE RBD IgG, and hence assumed protective humoral immunity - in anti-CD20- or fingolimod-treated pwMS with low or absent humoral immunity despite full vaccination. The effect of a third vaccine dose was limited and more prominent among those treated with anti-CD20 therapy.

Association between ChAdOx1 nCoV-19 vaccination and bleeding episodes: large population-based cohort study (preprint)

Objective To compare prevalence of skin, nose and gingival bleedings after receipt of adeno-vectored or mRNA-vaccines against covid-19. The hypothesis is that milder symptoms indicating altered thrombocyte function may affect a larger proportion of vaccinated individuals than the recently reported severe cases with thrombosis and thrombocytopenia.Design Large, population-based cohort study.Setting Norway, nationwide.ParticipantsMore than 80 000 cohort participants responding to electronic questionnaires about covid-19 vaccination and potential side effects during weeks 11-13, 2021. Response rate 58% (81267/138924), 83% were female, 85% health care workers and 80% were aged 40-55 years. Main outcome measuresSelf-reported episodes of skin, nose and gingival bleedings. Variation in rates by registered vaccine type, age, sex, occupation, previous covid-19 infection and chronic disease. ResultsFour of the 3416 subjects (0.2%) who were vaccinated with a single dose of mRNA vaccine reported skin bleeding as a side effect, as opposed to 163 of 5132 subjects (3.2%) vaccinated with a single dose of the adenovirus-vectored vaccine, OR (odds ratio)=16.0 (95% confidence interval (CI) 7.5-34.1). Corresponding ORs for nose and gingival bleeding were 8.0 (4.0-15.8) and 9.3 (4.3-20.0), respectively.ConclusionsThese findings could potentially indicate that the adenovirus-vectored vaccine may lead to mild bleeding episodes in a larger proportion of vaccinated individuals, and not only in rare cases with documented thrombosis and thrombocytopenia. Studies are needed to understand the possible mechanisms behind these observations, and to establish or refute whether they share similarities with the severe thromboembolic bleeding complications.  

Preexisting Cross-Reactive T Cells are Boosted and Comprise Significant Immunity in COVID-19 Recovered Patients (preprint)

Most SARS-CoV-2 infected individuals develop symptoms that do not require medical management. We hypothesized that pre-existing cross-reactive T cell responses could protect the majority from severe disease. Here we found that CTL and Th cells specific for seasonal human coronaviruses (HCoV) were significantly expanded in recovered COVID-19 donors and that CTL responses were significantly higher than responses to private SARS-CoV-2 peptides not shared with seasonal HCoV. A third of the SARS-CoV-2 peptide:HLA ligandome was matched by highly similar peptide mimics from seasonal HCoV, constituting a common HCoV peptide pool. CTL immunity was significantly skewed to the common HCoV peptide pool in age groups 20-70y, but not >70y-old donors. Over 40% of recovered donors lacked neutralizing antibodies, highlighting the role of T cell immunity in COVID-19. Results suggest a protective pre-acquired T cell immunity to SARS-CoV-2 and identify epitopes that may help boost vaccine responses and ensure broad protection against this family of viruses.Trial Registration: ClinicalTrials.gov: NCT04320732.Funding: This study was funded by The Health-South East Health Authority (Project 29286), the Research Council of Norway (Project 312693), the Oslo University Hospital, the KG Jebsen Foundation (grant 19), the University of Oslo, The Norwegian Cancer Society.Conflict of Interest: The authors declare that we have no competing interests.