Immune profiling of COVID-19 vaccine responses in people with multiple sclerosis on B cell-depleting therapy (preprint)

Background and ObjectivePeople with multiple sclerosis (pwMS) receiving B cell-depleting therapies have impaired antibody responses to vaccination. In a proportion of individuals, repeat vaccination against COVID-19 leads to seroconversion. We sought to describe the immune phenotype of pwMS on ocrelizumab, and identify clinical and immunological determinants of an effective vaccine response. MethodsThis was a single-centre, prospective cohort study. Peripheral blood samples were collected from pwMS receiving ocrelizumab (n = 38) pre and post administration of a third dose of mRNA COVID-19 vaccine. Immunogenicity was measured by T cell IFN{gamma} ELISpot, antibody titres, and live virus neutralisation. Humoral immunity was benchmarked against pwMS receiving natalizumab (n = 15), and against a correlate of real-world protection (50% reduction in incidence of infection) from SARS-CoV-2 ancestral and omicron BA.5 variants. The peripheral immune phenotype was comprehensively assessed by flow cytometry, and potential clinical and phenotypic determinants of response to vaccination identified. ResultsImmune cell populations relevant to disease and vaccine response were altered in pwMS receiving ocrelizumab versus natalizumab treatment, including depleted CD20-expressing B cell, T cell and NK cell populations, and elevated CD27+CD38+ T cell and NK8 cell frequencies. Following a third vaccine dose, 51% of pwMS on ocrelizumab were seropositive for SARS-CoV-2 receptor-binding-domain IgG, and 25% and 14% met the threshold for effective neutralisation of live SARS-CoV-2 ancestral and omicron BA.5 virus, respectively. B cell frequency at the time of vaccination, but not time since ocrelizumab infusion, was positively correlated with antibody response, while a strong negative correlation was observed between CD56bright NK cell frequency and antibody response in the ocrelizumab group. In this exploratory cohort, CD3-CD20+ B cells (% of lymphocytes; OR=3.92) and CD56bright NK cells (% of NK cells; OR=0.94) were predictive of an effective neutralising antibody response in second dose non-responders (AUC: 0.98). DiscussionOcrelizumab treatment was associated with an altered immune phenotype, including recently described T cell and NK populations with potential roles in disease pathogenesis. However, seroconversion was severely impaired by ocrelizumab, and less than half of those who seroconverted following a third vaccine dose demonstrated effective immunity against SARS-CoV-2 ancestral or omicron BA.5. B cell frequency was associated with an effective antibody response, while immunomodulatory CD56bright NK cells were identified as a potential negative determinant of response in those with inadequate B cell numbers. Immune phenotype rather than time since ocrelizumab infusion may help to stratify individuals for prophylaxis.

mTOR inhibition improves the formation of functional T cell memory following COVID-19 vaccination of kidney transplant recipients (preprint)

Inadequate immune response to vaccination is a long-standing problem faced by immunosuppressed kidney transplant recipients (KTRs), requiring novel strategies to improve vaccine efficacy. In this study, the potential of mechanistic target of rapamycin inhibitors (mTORi) to improve T cell responses to COVID-19 vaccination was investigated. Following primary vaccination with adenoviral (ChAdOx1) or mRNA (BNT162b2) COVID-19 vaccines, KTRs receiving rapamycin demonstrated T cell responses greater than those of healthy individuals, characterized by increased frequencies of vaccine-specific central memory, effector memory and TEMRA T cells, in both the CD4+ and CD8+ compartments. Relative to standard-of-care triple therapy, mTORi-based therapy was associated with a 12-fold greater functional T cell response to primary vaccination of KTRs. The use of rapamycin to augment T cell responses to COVID-19 booster (third dose) vaccination was next investigated in a randomized, controlled trial. Immunosuppression modification with rapamycin was feasible and well-tolerated, but did not improve vaccine-specific T cell responses in this cohort. To understand the parameters for effective use of rapamycin as a vaccine adjuvant, mice were treated with rapamycin before primary or booster vaccination with ancestral and/or Omicron COVID-19 vaccines. Supporting the findings from KTRs, significant enhancement of functional and stem-like memory T cell responses was observed when rapamycin was administered from the time of primary, rather than booster, vaccination. Collectively, a positive effect of mTOR inhibitors on vaccine-induced T cell immunity against COVID-19 in humans was demonstrated.

AstraZeneca ChAdOx1-S COVID-19 Vaccine Can Be Safely Administered in Patients with EDTA Allergy (preprint)

Background: Immediate hypersensitivity reactions to COVID-19 vaccines have been postulated to be linked to their excipients, such as polyethylene glycol (PEG) in Pfizer Comirnaty, or polysorbate 80 and ethylenediaminetetracetic acid (EDTA) in AstraZeneca ChAdOx1-S [recombinant] (Vaxzevria). These excipients are potentially found in a range of other products, including injectable and oral medications as well as intravenous radiocontrast media (RCM) and various cosmetic products.Currently patients with proven excipient allergy may be advised to avoid a COVID-19 vaccine containing that excipient and/or potentially cross-reactive excipients. We present two cases of previously confirmed EDTA anaphylaxis, who had negative Vaxzevria vaccine in- vivo testing and subsequently tolerated the vaccine. Case 1: A patient with history of anaphylaxis to RCM and local anaesthetics (LA) had positive intradermal test (IDT) to EDTA nine years earlier. Skin testing to Vaxzeria vaccine (up to 1:10 IDT), Comirnaty vaccine (up to 1:10 IDT) and EDTA 0.3mg/mL IDT were negative. However, following EDTA 3mg/ml IDT, he developed immediate generalised urticaria without anaphylaxis. Basophil activation testing was negative to disodium EDTA, Vaxzevria and Cominarty vaccines. Given the negative in- vitro and in- vivo testing to Vaxzevria vaccine, he proceeded to Vaxzevria immunisation and tolerated both doses. Case 2 A patient with history of anaphylaxis to RCM had positive skin testing to EDTA and RCM containing EDTA six years earlier. Following referral to COVID19 vaccine clinic, Vaxzevria vaccine (1:10 IDT) and Cominarty vaccine (1:10 IDT) were negative whilst EDTA was positive at 0.3mg/mL IDT. He subsequently tolerated both Vaxzevria vaccinations. Conclusion: Excipient allergy does not necessarily preclude a patient from receiving a vaccine containing that excipient. Allergy testing can help identify excipient-allergic patients who may still tolerate vaccination, which is important in situations where COVID-19 vaccination options are limited.