Obesity Differs from Diabetes Mellitus in Antibody and T Cell Responses Post COVID-19 Recovery (preprint)

Objective: Obesity and type 2 diabetes (DM) are risk factors for severe COVID-19 outcomes, which disproportionately affect South Asian populations. This study aims to investigate the humoral and cellular immune responses to SARS-CoV-2 in adult COVID-19 survivors with obesity and DM in Bangladesh. Methods: In this cross-sectional study, SARS-CoV-2-specific antibody and T cell responses were investigated in 63 healthy and 75 PCR-confirmed COVID-19 recovered individuals in Bangladesh, during the pre-vaccination first wave of the COVID-19 pandemic in 2020. Results: In COVID-19 survivors, SARS-CoV-2 infection induced robust antibody and T cell responses, which correlated with disease severity. After adjusting for age, sex, DM status, disease severity, and time since onset of symptoms, obesity was associated with decreased neutralising antibody titers, and increased SARS-CoV-2 spike-specific IFN-{gamma} response along with increased proliferation and IL-2 production by CD8+ T cells. In contrast, DM was not associated with SARS-CoV-2-specific antibody and T cell responses after adjustment for obesity and other confounders. Conclusions: Obesity is associated with lower neutralising antibody levels and higher T cell responses to SARS-CoV-2 post COVID-19 recovery, while antibody or T cell responses remain unaltered in DM.

CD4+ and CD8+ T cell and antibody correlates of protection against Delta vaccine breakthrough infection: A nested case-control study within the PITCH study (preprint)

T cell correlates of protection against SARS-CoV-2 infection after vaccination ('vaccine breakthrough') are incompletely defined, especially the specific contributions of CD4+ and CD8+ T cells. We studied 279 volunteers in the Protective Immunity from T Cells in Healthcare Workers (PITCH) UK study, including 32 cases (with SARS-CoV-2 positive testing after two vaccine doses during the Delta-dominant era) and 247 controls (no positive test nor anti-nucleocapsid seroconversion during this period). 28 days after second vaccination, before all breakthroughs occurred, cases had lower ancestral S- and RBD-specific immunoglobulin G titres and S1- and S2-specific T cell interferon gamma (IFN{gamma}) responses compared with controls. In a subset of matched cases and controls, cases had lower CD4+ and CD8+ IFN{gamma} and tumour necrosis factor responses to Delta S peptides with reduced CD8+ responses to Delta versus ancestral peptides compared with controls. Our findings support a protective role for T cells against Delta breakthrough infection.

Omicron BA.1/BA.2 infections in triple-vaccinated individuals enhance a diverse repertoire of mucosal and blood immune responses (preprint)

Pronounced immune escape by the SARS-CoV-2 Omicron variant has resulted in large numbers of individuals with hybrid immunity, generated through a combination of vaccination and infection. Based primarily on circulating neutralizing antibody (NAb) data, concerns have been raised that omicron breakthrough infections in triple-vaccinated individuals result in poor induction of omicron-specific immunity, and that a history of prior SARS-CoV-2 in particular is associated with profound immune dampening. Taking a broader and comprehensive approach, we characterized mucosal and blood immunity to both spike and non-spike antigens following BA.1/BA.2 infections in triple mRNA-vaccinated individuals, with and without a history of previous SARS-CoV-2 infection. We find that the majority of individuals increase BA.1/BA.2/BA.5-specific NAb following infection, but confirm that the magnitude of increase and post-omicron titres are indeed higher in those who were infection-naive. In contrast, significant increases in nasal antibody responses are seen regardless of prior infection history, including neutralizing activity against BA.5 spike. Spike-specific T cells increase only in infection-naive vaccinees; however, post-omicron T cell responses are still significantly higher in previously-infected individuals, who appear to have maximally induced responses with a CD8+ phenotype of high cytotoxic potential after their 3rd mRNA vaccine dose. Antibody and T cell responses to non-spike antigens also increase significantly regardless of prior infection status, with a boost seen in previously-infected individuals to immunity primed by their first infection. These findings suggest that hybrid immunity induced by omicron breakthrough infections is highly dynamic, complex, and compartmentalised, with significant immune enhancement that can help protect against COVID-19 caused by future omicron variants.

Efficacy of ultra-short, response-guided sofosbuvir and daclatasvir therapy for Hepatitis C: a single arm mechanistic pilot study (preprint)

ABSTRACT Background WHO has called for research into predictive factors for selecting persons who could be successfully treated with shorter durations of direct acting antiviral (DAA) therapy for Hepatitis C. We evaluated early virological response as a means of shortening treatment and explored host, viral and pharmacokinetic contributors to treatment outcome. Methods Duration of sofosbuvir and daclatasvir (SOF/DCV) was determined according to day 2 (D2) virologic response for HCV genotype (gt) 1- or 6-infected adults in Vietnam with mild liver disease. Participants received 4 or 8 weeks treatment according to whether D2 HCV RNA was above or below 500 IU/ml (standard duration is 12 weeks). Primary endpoint was sustained virological response (SVR12). Those failing therapy were retreated with 12 weeks SOF/DCV. Host IFNL4 genotype and viral sequencing was performed at baseline, with repeat viral sequencing if virological rebound was observed. Levels of SOF, its inactive metabolite GS-331007 and DCV were measured on day 0 and 28. Results Of 52 adults enrolled, 34 received 4 weeks SOF/DCV, 17 got 8 weeks and one withdrew. SVR12 was achieved in 21/34 (62%) treated for 4 weeks, and 17/17 (100%) treated for 8 weeks. Overall 38/51 (75%) were cured with first-line treatment (mean duration 37 days). Despite a high prevalence of putative NS5A-inhibitor resistance associated substitutions (RAS), all first-line treatment failures cured after retreatment (13/13). We found no evidence treatment failure was associated with host IFNL4 genotype, viral subtype, baseline RAS or DCV levels. SOF metabolite levels were higher in those failing 4-week therapy. Conclusions Shortened SOF/DCV therapy, with retreatment if needed, reduces DAA use while maintaining high cure rates. D2 virologic response alone does not adequately predict SVR12 with 4 weeks treatment. Funding Funded by the Medical Research Council (grant MR/P025064/1) and The Global Challenges Research Fund (Wellcome Trust Grant 206/296/Z/17/Z).) Clinical trial number ISRCTN17100273

Evolution of long-term hybrid immunity in healthcare workers after different COVID-19 vaccination regimens: a longitudinal observational cohort study (preprint)

Both infection and vaccination, alone or in combination, generate antibody and T cell responses against SARS-CoV-2. However, the maintenance of such responses - and hence protection from disease - requires careful characterisation. In a large prospective study of UK healthcare workers (PITCH, within the larger SIREN study) we previously observed that prior infection impacted strongly on subsequent cellular and humoral immunity induced after long and short dosing intervals of BNT162b2 (Pfizer/BioNTech) vaccination. Here, we report longer follow up of 684 HCWs in this cohort over 6-9 months following two doses of BNT162b2 or AZ1222 (Oxford/AstraZeneca) vaccination and following a subsequent BNT162b2 booster vaccination. We make three important observations: Firstly, the dynamics of humoral and cellular responses differ; binding and neutralising antibodies declined whereas T and B cell responses were better maintained after the second vaccine dose. Secondly, vaccine boosting restored IgG levels to post second dose levels and broadened neutralising activity against variants of concern including omicron BA.1, alongside further boosting of T cell responses. Thirdly, prior infection maintained its impact driving larger T cell responses compared to never infected people, including after the third dose. In conclusion, the maintenance of T cell responses in time and against variants of concern may account for continued protection against severe disease.

Further antibody escape by Omicron BA.4 and BA.5 from vaccine and BA.1 serum (preprint)

The Omicron lineage of SARS-CoV-2, first described in November 2021, spread rapidly to become globally dominant and has split into a number of sub-lineages. BA.1 dominated the initial wave but has been replaced by BA.2 in many countries. Recent sequencing from South Africa's Gauteng region uncovered two new sub-lineages, BA.4 and BA.5 which are taking over locally, driving a new wave. BA.4 and BA.5 contain identical spike sequences and, although closely related to BA.2, contain further mutations in the receptor binding domain of spike. Here, we study the neutralization of BA.4/5 using a range of vaccine and naturally immune serum and panels of monoclonal antibodies. BA.4/5 shows reduced neutralization by serum from triple AstraZeneca or Pfizer vaccinated individuals compared to BA.1 and BA.2. Furthermore, using serum from BA.1 vaccine breakthrough infections there are likewise, significant reductions in the neutralization of BA.4/5, raising the possibility of repeat Omicron infections.

Comparison of two T cell assays to evaluate T cell responses to SARS-CoV-2 following vaccination in naive and convalescent healthcare workers (preprint)

Background: T cell responses to SARS-CoV-2 following infection and vaccination are less characterised than antibody responses, due to a more complex experimental pathway. Methods: We measured T cell responses in 108 healthcare workers (HCWs) in an observational cohort study, using the commercialised Oxford Immunotec T-SPOT Discovery SARS-CoV-2 assay (OI T-SPOT) and the PITCH ELISpot protocol established for academic research settings. Results: Both assays detected T cell responses to SARS-CoV-2 spike, membrane and nucleocapsid proteins. Responses were significantly lower when reported by OI T-SPOT than by PITCH ELISpot. Four weeks after two doses of either Pfizer/BioNTech BNT162b or ChAdOx1 nCoV-19 AZD1222 vaccine, the responder rate was 63% for OI T-SPOT Panels1+2 (peptides representing SARS-CoV-2 spike protein excluding regions present in seasonal coronaviruses), 69% for OI T-SPOT Panel 14 (peptides representing the entire SARS-CoV-2 spike), and 94% for the PITCH ELISpot assay. The two OI T-SPOT panels correlated strongly with each other showing that either readout quantifies spike-specific T cell responses, although the correlation between the OI T-SPOT panels and the PITCH ELISpot was moderate. Conclusion: The standardisation, relative scalability and longer interval between blood acquisition and processing are advantages of the commercial OI T-SPOT assay. However, the OI T-SPOT assay measures T cell responses at a significantly lower magnitude compared to the PITCH ELISpot assay, detecting T cell responses in a lower proportion of vaccinees. This has implications for the reporting of low-level T cell responses that may be observed in patient populations and for the assessment of T cell durability after vaccination.

Impact of the COVID-19 pandemic on routine surveillance for adults with chronic hepatitis B virus (HBV) infection in the UK. (preprint)

Background and aimsTo determine the impact of the COVID-19 pandemic on the population with chronic Hepatitis B virus (HBV) infection under hospital follow-up in the UK, we quantified the coverage and frequency of measurements of biomarkers used for routine surveillance (ALT and HBV viral load). MethodsWe used anonymised electronic health record data from the National Institute for Health Research (NIHR) Health Informatics Collaborative (HIC) pipeline representing five UK NHS Trusts. ResultsWe report significant reductions in surveillance of both biomarkers during the pandemic compared to pre-COVID years, both in terms of the proportion of patients who had [≥]1 measurement annually, and the mean number of measurements per patient. ConclusionsFurther investigation is required to determine whether these disruptions will be associated with increased rates of adverse chronic HBV outcomes.

Combination therapy of infliximab and thiopurines, but not monotherapy with infliximab or vedolizumab, is associated with attenuated IgA and neutralisation responses to SARS-CoV-2 in inflammatory bowel disease (preprint)

There is substantial interest regarding the perceived risk that immunomodulator and biologic therapy could have on COVID-19 disease severity among patients with inflammatory bowel disease (IBD) and clinicians. In this study, we show that infliximab/thiopurine combination therapy is associated with significantly lower IgA, a range of lower IgG responses as well as impaired neutralising antibody responses, compared to responses observed in healthy individuals. We also demonstrate that whilst IgG responses were significantly reduced in individuals with IBD treated with infliximab or vedolizumab monotherapy compared to healthy controls, there was no significant reduction in IgA and neutralising antibody responses. As neutralising antibody responses correlate with protection, this observation may provide the mechanistic explanation for the observation reported by the SECURE-IBD study that individuals on infliximab/thiopurine combination therapy were at greater risk of severe COVID-19 outcomes than patients on monotherapy.

Poor Antibody Responses to SARS-CoV-2 Infection or Vaccination Are Associated With High Re-Infection Rates in Haemodialysis and Renal Transplant Patients (preprint)

Background: Patients with end-stage renal disease (ESRD) are vulnerable to SARS-CoV-2 infection and mount poor antibody responses to standard vaccines. We addressed whether ESRD patients could mount immune responses that protected against re-infection following natural SARS-CoV-2 infection or 2-dose vaccination.Methods: Haemodialysis (HD and renal transplant patients were recruited following SARS-CoV-2 infection (n=46) or before SARS-CoV-2 vaccination (n=94). SARS-CoV-2 IgG responses, surrogate neutralising antibody (NAb) titres to wildtype and VOCs, T cell responses and viral sequencing in the vaccine-naïve convalescent cohort were serially assessed following infection. Surrogate NAb titres were measured pre-vaccination and 33 days after 2nd vaccine. Incidence of breakthrough infection was assessed 180 days following 1st vaccination. Findings: 22% of vaccine-naive HD (n=9/36) and transplant patients (n=1/10) demonstrated PCR-positive re-infection (RI) at median 212 days (IQR 140-239) post 1st infection. Prior to RI episodes, RI patients demonstrated poor IgG Spike and RBD responses which were equivalent to levels in pre-pandemic sera (median RI titres: Spike 187 AU/ml, IQR 143-3432, p=0.96; RBD 145 AU/ml, IQR 85-938, p>0.99), unlike patients who developed a single infection only (SI) when compared to pre-pandemic sera (median SI titres: Spike 22826 AU/ml, IQR 1255-63811, p<0.0001; RBD 9588 AU/ml, IQR 270-21616, p=0.001). IgG Spike and RBD titres increased following RI compared to pre-pandemic sera (median RI titres: Spike 22611 AU/ml, IQR 4488-75509, p=0.0006; RBD 6354 AU/ml, IQR 1671-20962, p=0.01). T cell analysis revealed no differences between RI and SI cohorts. Following 2-dose vaccination, 5% of the HD cohort who received AZD1222 (n=3/61) developed breakthrough infection at 6 months following 1st vaccination, unlike those who received BNT162b2 (n=0/16). AZD1222-vaccinated, infection-naïve (I-N) HD patients (n=32) and immunosuppressed transplant recipients (n=17) made poor NAb responses to wildtype, alpha, beta and gamma when compared to infection-experienced (I-E) HD patients (n=29) (I-N vs I-E HD wildtype p<0.0001, alpha p=0.0007, beta p<0.0001, gamma p=0.002). NAb responses improved with BNT162b2 vaccination (n=16); RI patients mounted larger NAb responses to AZD1222 vaccination than SI patients (wildtype p=0.01, alpha p=0.02, beta p<0.02). Interpretation: ESRD patients are highly susceptible to SARS-CoV-2 re-infection, or breakthrough infection following vaccination, associated with poor protective antibody responses. SARS-CoV-2-specific IgG and surrogate NAb responses increase with repeated exposure (infection experience and/or vaccination) in patients who survive infections. Our findings support the case for specific booster regimens in such immune-incompetent patients. Funding Information: Oxford Transplant Foundation, Oxfordshire Health Services Research Committee, UK Department of Health and Social Care, Huo Family Foundation, NIHR (COV19-RECPLAS), UK Coronavirus Immunology Consortium, NIHR Oxford Biomedical Research Centre, WT109965MA.Declaration of Interests: We declare no competing interestsEthics Approval Statement: Haemodialysis (HD) and transplant cohorts: In this prospective, observational cohort study, HD and transplant patients within Oxford University Hospitals NHS Foundation Trust(OUH) were recruited under Oxford Radcliffe Biobank approved studies, “Biomarkers to stratify risk in Renal Transplant Recipients and Dialysis Patients with Covid-19” (ref: ORB 20/A056), and “Immunological responses to COVID-19 vaccines in transplant and haemodialysis patients” (ref: ORB 21/A014). The Oxford Radcliffe Biobank has a favorable ethics opinion from the South Central Oxford Committee C (REC: 19/SC/0173). Healthcare Worker cohort (HC, PITCH study): PITCH is a sub-study of the SIREN study which was approved by the Berkshire Research Ethics Committee, Health Research 250 Authority (IRAS ID 284460, REC reference 20/SC/0230), with PITCH recognised as a sub-study on 2 December 2020. SIREN is registered with ISRCTN (Trial ID:252 ISRCTN11041050)The study was conducted in compliance with all relevant ethical regulations for work with human participants, and according to the principles of the Declaration of Helsinki (2008) and the International Conference on Harmonization (ICH) Good Clinical Practice (GCP) guidelines. Written informed consent was obtained for all patients enrolled in the study.

Durability of ChAdOx1 nCov-19 (AZD1222) vaccination in people living with HIV - responses to SARS-CoV-2, variants of concern and circulating coronaviruses (preprint)

Duration of protection from SARS-CoV-2 infection in people with HIV (PWH) following vaccination is unclear. In a sub-study of the phase 2/3 the COV002 trial (NCT04400838), 54 HIV positive male participants on antiretroviral therapy (undetectable viral loads, CD4+ T cells >350 cells/ul) received two doses of ChAdOx1 nCoV-19 (AZD1222) 4-6 weeks apart and were followed for 6 months. Responses to vaccination were determined by serology (IgG ELISA and MesoScale Discovery (MSD)), neutralisation, ACE-2 inhibition, gamma interferon ELISpot, activation-induced marker (AIM) assay and T cell proliferation. We show that 6 months after vaccination the majority of measurable immune responses were greater than pre-vaccination baseline, but with evidence of a decline in both humoral and cell mediated immunity. There was, however, no significant difference compared to a cohort of HIV-uninfected individuals vaccinated with the same regimen. Responses to the variants of concern were detectable, although were lower than wild type. Pre-existing cross-reactive T cell responses to SARS-CoV-2 spike were associated with greater post-vaccine immunity and correlated with prior exposure to beta coronaviruses. These data support the on-going policy to vaccinate PWH against SARS-CoV-2, and underpin the need for long-term monitoring of responses after vaccination.

Examining the Immunological Effects of COVID-19 Vaccination in Patients with Conditions Potentially Leading to Diminished Immune Response Capacity – The OCTAVE Trial (preprint)

SARS-COV-2 vaccines have been shown to be efficacious primarily in healthy volunteer populations and population level studies. Immune responses following SARS-CoV-2 vaccination are less well characterised in potentially immune vulnerable patient groups, including those with immune-mediated inflammatory and chronic diseases (inflammatory arthritis [IA] incorporating rheumatoid arthritis [RA] and psoriatic arthritis [PsA]; ANCA-Associated Vasculitis [AAV]; inflammatory bowel disease [IBD]); hepatic disease (HepD), end stage kidney disease requiring haemodialysis (HD) without or with immunosuppression (HDIS); solid cancers (SC) and haematological malignancies (HM), and those that have undergone haemopoietic stem cell transplant (HSCT). The OCTAVE trial is a multi-centre, multi-disease, prospective cohort that will comprehensively assess SARS-CoV-2 vaccine responses within and between the abovementioned disease cohorts using common analytical platforms in patients recruited across the United Kingdom (UK). The majority of subjects received either COVID-19 mRNA Vaccine BNT162b2 (Pfizer/BioNTech) or ChAdOx1 Vaccine (AstraZeneca formerly AZD1222) as part of the UK National COVID19 vaccination programme. As of 13 th August 2021; 2,583 patients have been recruited. We report herein the humoral and T cell immune response results from the first 600 participants recruited where serology data are available at baseline, pre-second vaccine dose (boost) and/or 4 weeks post second dose. We also include in the analysis, data obtained from 231 healthy individuals from the PITCH (Protective Immunity from T cells in Healthcare workers) study. Overall, in comparison to PITCH where 100% of tested individuals (n=93) generated anti-Spike antibodies after vaccine doses, 89% of patients within OCTAVE seroconverted 4 weeks after second vaccine dose. By corollary, approximately 11% of patients across all disease cohorts fail to generate antibodies that react to SARS-CoV-2 spike 4 weeks after two vaccines. Failure to generate spike reactive antibodies was found at a higher proportion in some specific patient subgroups, particularly AAV (72.4%), HD-IS (16.7%) and HepD (16.7%). Importantly, all recruited AAV patients had received Rituximab; a targeted B cell depletion therapy. Furthermore, even in those who seroconverted, 40% of patients across disease cohorts generate lower levels of SARS-CoV-2 antibody reactivity compared to healthy subjects after two SARS-CoV-2 vaccines; the functional significance of these findings in providing protection from subsequent SARS-CoV-2 exposure is not currently known. In contrast to the observed serological response, evaluation of the Spike-specific T cell response revealed that across all patient sub-groups (including AAV) a response similar to healthy individuals was generated. Our data argue strongly for further vaccination strategies to optimise humoral immune responses against SARS-CoV-2 in patients with chronic diseases and/or patients on immune suppressive therapies. Trial Registration: The trial is registered on ISRCTN 12821688.Funding: This work was supported by the Medical Research Council COVID-19 Immunity – National Core Study (IMM-NCS) [grant number MC-PC-20031]. Staff at the Cancer Research UK Clinical Trials Unit (CRCTU) are supported by a core funding grant from Cancer Research UK (C22436/A25354). PK and EB are supported by the NIHR Birmingham Biomedical Research Centres at the University Hospitals Birmingham NHS Foundation Trust and the University of Birmingham Biomedical Research Centres. EB and PK are supported by an NIHR Senior Investigator award. PK is funded by WT109965MA. SJD is funded by an NIHR Global Research Professorship (NIHR300791). TdS is funded by a Wellcome Trust Intermediate Clinical Fellowship (110058/Z/15/Z). DS is supported by the NIHR Academic Clinical Lecturer programme in Oxford. LT is supported by the Wellcome Trust (grant number 205228/Z/16/Z), the U.S. Food and Drug Administration Medical Countermeasures Initiative contract 75F40120C00085. and the National Institute for Health Research Health Protection Research Unit (NIHR HPRU) in Emerging and Zoonotic Infections (NIHR200907) at University of Liverpool in partnership with Public Health England (PHE), in collaboration with Liverpool School of Tropical Medicine and the University of Oxford. The PITCH (Protective Immunity from T cells to Covid-19 in Health workers) Consortium, is funded by the UK Department of Health and Social Care with contributions from UKRI/NIHR through the UK Coronavirus Immunology Consortium (UKCIC), the Huo Family Foundation and The National Institute for Health Research (UKRIDHSC COVID-19 Rapid Response Rolling Call, Grant Reference Number COV19-RECPLAS).Declaration of Interest: None to declare. Ethical Approval: This study was approved by the UK Medicines and Healthcare Products Regulatory Agency on the 5th February 2021 and the London and Chelsea Research Ethics Committee (REC Ref:21/HRA/0489) on 12th February 2021, with subsequent amendments approved on 3rd March 2021, 19th April 2021 and 26th April 2021).

Divergent trajectories of antiviral memory after SARS-Cov-2 infection (preprint)

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection is normally controlled by effective host immunity including innate, humoral and cellular responses. However, the trajectories and correlates of acquired immunity, and the capacity of memory responses months after infection to neutralise variants of concern - which has important public health implications - is not fully understood. To address this, we studied a cohort of 78 UK healthcare workers who presented in April to June 2020 with symptomatic PCR-confirmed infection or who tested positive during an asymptomatic screening programme and tracked virus-specific B and T cell responses longitudinally at 5-6 time points each over 6 months, prior to vaccination. We observed a highly variable range of responses, some of which - T cell interferon-gamma (IFN-γ) ELISpot, N-specific antibody waned over time across the cohort, while others (spike-specific antibody, B cell memory ELISpot) were stable. In such cohorts, antiviral antibody has been linked to protection against re-infection. We used integrative analysis and a machine-learning approach (SIMON - Sequential Iterative Modeling Over Night) to explore this heterogeneity and to identify predictors of sustained immune responses. Hierarchical clustering defined a group of high and low antibody responders, which showed stability over time regardless of clinical presentation. These antibody responses correlated with IFN-γ ELISpot measures of T cell immunity and represent a subgroup of patients with a robust trajectory for longer term immunity. Importantly, this immune-phenotype associates with higher levels of neutralising antibodies not only against the infecting (Victoria) strain but also against variants B.1.1.7 (alpha) and B.1.351 (beta). Overall memory responses to SARS-CoV-2 show distinct trajectories following early priming, that may define subsequent protection against infection and severe disease from novel variants.

FXR inhibition reduces ACE2 expression, SARS-CoV-2 infection and may improve COVID-19 outcome (preprint)

Prevention of SARS-CoV-2 entry in cells through the modulation of viral host receptors, such as ACE2, could represent a new therapeutic approach complementing vaccination. However, the mechanisms controlling ACE2 expression remain elusive. Here, we identify the farnesoid X receptor (FXR) as a direct regulator of ACE2 transcription in multiple COVID19-affected tissues, including the gastrointestinal and respiratory systems. We demonstrate that FXR antagonists, including the over-the-counter compound z-guggulsterone (ZGG) and the off-patent drug ursodeoxycholic acid (UDCA), downregulate ACE2 levels, and reduce susceptibility to SARS-CoV-2 infection in lung, cholangiocyte and gut organoids. We then show that therapeutic levels of UDCA downregulate ACE2 in human organs perfused ex situ and reduce SARS-CoV-2 infection ex vivo. Finally, we perform a retrospective study using registry data and identify a correlation between UDCA treatment and positive clinical outcomes following SARS-CoV-2 infection, including hospitalisation, ICU admission and death. In conclusion, we identify a novel function of FXR in controlling ACE2 expression and provide evidence that this approach could be beneficial for reducing SARS-CoV-2 infection, thereby paving the road for future clinical trials.

A blood atlas of COVID-19 defines hallmarks of disease severity and specificity (preprint)

Treatment of severe COVID-19 is currently limited by clinical heterogeneity and incomplete understanding of potentially druggable immune mediators of disease. To advance this, we present a comprehensive multi-omic blood atlas in patients with varying COVID-19 severity and compare with influenza, sepsis and healthy volunteers. We identify immune signatures and correlates of host response. Hallmarks of disease severity revealed cells, their inflammatory mediators and networks as potential therapeutic targets, including progenitor cells and specific myeloid and lymphocyte subsets, features of the immune repertoire, acute phase response, metabolism and coagulation. Persisting immune activation involving AP-1/p38MAPK was a specific feature of COVID-19. The plasma proteome enabled sub-phenotyping into patient clusters, predictive of severity and outcome. Tensor and matrix decomposition of the overall dataset revealed feature groupings linked with disease severity and specificity. Our systems-based integrative approach and blood atlas will inform future drug development, clinical trial design and personalised medicine approaches for COVID-19.

Fatal COVID-19 outcomes are associated with an antibody response targeting epitopes shared with endemic coronaviruses (preprint)

It is unclear whether prior endemic coronavirus infections affect COVID-19 severity. Here, we show that in cases of fatal COVID-19, antibody responses to the SARS-COV-2 spike are directed against epitopes shared with endemic beta-coronaviruses in the S2 subunit of the SARS-CoV-2 spike protein. This immune response is associated with the compromised production of a de novo SARS-CoV-2 spike response among individuals with fatal COVID-19 outcomes.

Safety and Immunogenicity of the ChAdox1 nCoV-19 (AZD1222) Vaccine Against SARS-CoV-2 in HIV Infection (preprint)

Background: The ChAdOx1 nCoV-19 (AZD1222) vaccine is immunogenic and protects against COVID-19. However, data on vaccine immunogenicity are needed for the 40 million people living with HIV (PWH), who may have less functional immunity and more associated co-morbidities than the general population. Methods: Between the 5th and 24th November 2020, 54 adults with HIV, aged 18-55 years, were enrolled into a single arm open label vaccination study within the protocol of the larger phase 2/3 COV002 trial. A prime-boost regimen of ChAdOx1 nCoV-19, with two doses (5 × 1010 vp) was given 4-6 weeks apart. All participants were on antiretroviral therapy (ART) with undetectable plasma HIV viral loads and CD4+ T cell counts >350 cells/µl at enrolment. Data were captured on adverse events. Humoral responses were measured by anti-spike IgG ELISA and antibody-mediated live virus neutralisation. Cell-mediated immune responses were measured by ex-vivo interferon-γ enzyme-linked immunospot assay (ELISpot) and T cell proliferation. All outcomes were compared with a HIV uninfected group from the main COV002 study.Findings: 54 participants with HIV (median age 42.5 years (IQR 37.2-49.8)) received two doses of ChAdOx1 nCoV-19. Median CD4+ T cell count at enrolment was 694 cells/µl (IQR 562-864). Results are reported for 56 days of follow-up. Local and systemic reactions occurring during the first 7 days after prime vaccination included pain at the injection site (49%), fatigue (47%), headache (47%), malaise (34%), chills (23%), and muscle or (36%) joint pain (9%), the frequencies of which were similar to the HIV-negative participants. There were no serious adverse events. Anti-spike IgG responses by ELISA peaked at Day 42 (median 1440 ELISA units, IQR 704-2728) and were sustained out to Day 56. There was no correlation with CD4+ T cell count or age and the magnitude of the anti-spike IgG response at Day 56 (P>0.05 for both). ELISpot and T cell proliferative responses peaked between Day 14 and 28 after prime and were sustained through to Day 56. When compared to participants without HIV there was no statistical difference in magnitude or persistence of SARS-CoV-2 spike-specific humoral or cellular responses (P>0.05 for all analyses).Interpretation: In this study of PWH, vaccination with ChAdOx1 nCoV-19 was well tolerated and there was no difference in humoral and cell-mediated immune responses compared to an adult cohort without HIV who received the same vaccination regime. Trial Registration: Trial Registration number is NCT04400838. Funding: UK Research and Innovation, National Institutes for Health Research (NIHR), Coalition for Epidemic Preparedness Innovations, NIHR Oxford Biomedical Research Centre, Thames Valley and South Midlands NIHR Clinical Research Network, and AstraZeneca. The views expressed are those of the author(s) and not necessarily those of the NIHR or the Department of Health and Social Care.Declaration of Interest: Oxford University has entered into a partnership with AstraZeneca for further development of ChAdOx1 nCoV-19 (AZD1222). AstraZeneca reviewed the data from the study and the final manuscript before 474 submission, but the authors retained editorial control. SCG is cofounder of Vaccitech (a collaborator in the early development of this vaccine candidate) and named as an inventor on a patent covering use of ChAdOx1-vectored vaccines (PCT/GB2012/000467) and a patent application covering this SARS-CoV-2 vaccine. TL is named as an inventor on a patent application covering this SARS-CoV-2 vaccine and was consultant to Vaccitech. PMF is a consultant to Vaccitech. AJP is Chair of the UK Department of Health and Social Care’s JCVI, but does not participate in policy advice on coronavirus vaccines, and is a member of the WHO Strategic Advisory Group of Experts (SAGE). AVSH is a cofounder of and consultant to Vaccitech and is named as an inventor on a patent covering design and use of ChAdOx1-vectored vaccines (PCT/GB2012/000467).Ethical Approval: Written informed consent was obtained from all participants, and the trial was done in accordance with the principles of the Declaration of Helsinki and Good Clinical Practice. This study was approved in the UK by the Medicines and Healthcare products Regulatory Agency (reference 21584/0424/001-0001) and the South Central Berkshire Research Ethics Committee (reference 20/SC/0145). Vaccine use was authorised by Genetically Modified Organisms Safety Committees at each participating site.