evere acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has caused the global COVID-19 pandemic infecting more than 111 million people and causing 2.4 million deaths. Clinical disease in humans ranges from asymptomatic infection to pneumonia, severe respiratory compromise, multi-organ failure and systemic inflammatory syndromes. The rapid expansion and prolonged nature of the COVID-19 pandemic and its accompanying morbidity, mortality and destabilizing socioeconomic effects have made the development of SARS-CoV-2 therapeutics and vaccines an urgent global health priority 1. Indeed, the emergency use authorization and rapid deployment of antibody-based countermeasures, including mAbs, immune plasma therapy and messenger RNA, and inactivated and viral-vectored vaccines has provided hope for curtailing disease and ending the pandemic. The spike protein of the SARS-CoV-2 virion binds the cell-surface receptor angiotensin-converting enzyme 2 (ACE2) to promote entry into human cells 2. Because the spike protein is critical for viral entry, it has been targeted for vaccine development and therapeutic antibody interventions. SARS-CoV-2 S proteins are cleaved to yield S1 and S2 fragments. The S1 protein includes the N-terminal (NTD) and receptor-binding (RBD) domains, whereas the S2 protein promotes membrane fusion. The RBD is recognized by many potently neutralizing monoclonal antibodies 3-7 , protein-based inhibitors 8 and serum antibodies 9. The current suite of antibody therapeutics and vaccines was designed with a spike protein based on strains circulating during the early phases of the pandemic in 2020. More recently, variants with enhanced transmissibility have emerged in the United Kingdom (B.1.1.7), South Africa (B.1.351), Brazil (B.1.1.248) and elsewhere with multiple substitutions in the spike protein, including in the NTD and the receptor-binding motif (RBM) of the RBD. Preliminary studies with pseudoviruses suggest that neutralization by some antibodies and immune sera may be diminished against variants expressing mutations in the spike gene 10-13. Given these

Interplay between SARS-CoV-2 and the complement system Antiviral strategies. The complement system traces its origins to more than a billion years ago when primitive proteins evolved to protect cells from pathogens and to engage in intracellular metabolic processes (18, 19) (Figure 1A). The contemporary complement system lies at the interface between innate and adaptive immunity (20). It efficiently recognizes and eliminates viral pathogens via several mechanisms: opsonizing viruses and virus-infected cells (including lysing them), inducing an antiviral immunoinflammatory state, boosting virus-specific immune responses, and directly neutralizing cell-free viruses (21) (reviewed in ref. 22). Coronavirus disease 2019 (COVID-19), the disease caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has resulted in a global pandemic and a disruptive health crisis. COVID-19-related morbidity and mortality have been attributed to an exaggerated immune response. The role of complement activation and its contribution to illness severity is being increasingly recognized. Here, we summarize current knowledge about the interaction of coronaviruses with the complement system. We posit that (a) coronaviruses activate multiple complement pathways; (b) severe COVID-19 clinical features often resemble complementopathies; (c) the combined effects of complement activation, dysregulated neutrophilia, endothelial injury, and hypercoagulability appear to be intertwined to drive the severe features of COVID-19; (d) a subset of patients with COVID-19 may have a genetic predisposition associated with complement dysregulation; and (e) these observations create a basis for clinical trials of complement inhibitors in life-threatening illness.

Evidence suggests that immunogenicity to mRNA-based SARS-CoV-2 vaccination in immunosuppressed patients may be reduced. This study assessed the response to 2 doses of mRNA-based SARS-CoV-2 vaccine among 133 participants with underlying chronic inflammatory disease, many of whom were receiving glucocorticoids, B-cell depletion therapy, or other immunosuppressant therapy.

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BackgroundWe describe the early experiences of adults with systemic rheumatic disease who received the COVID-19 vaccine.MethodsFrom 2 April to 30 April 2021, we conducted an online, international survey of adults with systemic rheumatic disease who received COVID-19 vaccination. We collected patient-reported data on clinician communication, beliefs and intent about discontinuing disease-modifying antirheumatic drugs (DMARDs) around the time of vaccination, and patient-reported adverse events after vaccination.ResultsWe analysed 2860 adults with systemic rheumatic diseases who received COVID-19 vaccination (mean age 55.3 years, 86.7% female, 86.3% white). Types of COVID-19 vaccines were Pfizer-BioNTech (53.2%), Oxford/AstraZeneca (22.6%), Moderna (21.3%), Janssen/Johnson & Johnson (1.7%) and others (1.2%). The most common rheumatic disease was rheumatoid arthritis (42.3%), and 81.2% of respondents were on a DMARD. The majority (81.9%) reported communicating with clinicians about vaccination. Most (66.9%) were willing to temporarily discontinue DMARDs to improve vaccine efficacy, although many (44.3%) were concerned about rheumatic disease flares. After vaccination, the most reported patient-reported adverse events were fatigue/somnolence (33.4%), headache (27.7%), muscle/joint pains (22.8%) and fever/chills (19.9%). Rheumatic disease flares that required medication changes occurred in 4.6%.ConclusionAmong adults with systemic rheumatic disease who received COVID-19 vaccination, patient-reported adverse events were typical of those reported in the general population. Most patients were willing to temporarily discontinue DMARDs to improve vaccine efficacy. The relatively low frequency of rheumatic disease flare requiring medications was reassuring.

Complement activation has been implicated in the pathogenesis of severe SARS-CoV-2 infection. However, it remains to be determined whether increased complement activation is a broad indicator of critical illness (and thus, no different in COVID-19). It is also unclear which pathways are contributing to complement activation in COVID-19, and if complement activation is associated with certain features of severe SARS-CoV-2 infection, such as endothelial injury and hypercoagulability. To address these questions, we investigated complement activation in the plasma from patients with COVID-19 prospectively enrolled at two tertiary care centers: Washington University School of Medicine (n=134) and Yale School of Medicine (n=49). We compared our patients to two non-COVID cohorts: (a) patients hospitalized with influenza (n=54), and (b) patients admitted to the intensive care unit (ICU) with acute respiratory failure requiring invasive mechanical ventilation (IMV, n=22). We demonstrate that circulating markers of complement activation are elevated in patients with COVID-19 compared to those with influenza and to patients with non-COVID-19 respiratory failure. Further, the results facilitate distinguishing those who are at higher risk of worse outcomes such as requiring ICU admission, or IMV. Moreover, the results indicate enhanced activation of the alternative complement pathway is most prevalent in patients with severe COVID-19 and is associated with markers of endothelial injury (i.e., angiopoietin-2) as well as hypercoagulability (i.e., thrombomodulin and von Willebrand factor). Our findings identify complement activation to be a distinctive feature of COVID-19, and provide specific targets that may be utilized for risk prognostication, drug discovery and personalized clinical trials.

Objectives The treatment for COVID-19 often utilizes immune-modulating drugs. These drugs are also used in immune mediated inflammatory diseases (IMIDs). We performed a systematic review about seroconversion after SARS-CoV-2 vaccination in patients with IMIDs and impact of various drugs on seroconversion rates. Methods Electronic databases were searched to identify relevant studies reporting seroconversion rates following SARS-CoV-2 vaccination in IMIDs. We calculated the pooled seroconversion rates after a single or two doses of vaccination, pooled seroconversion rates in patients with specific IMIDs, and rates in patients on various drugs/drug classes. Results Twenty-five studies were included in the systematic review. The pooled seroconversion rates after two doses of mRNA vaccination were higher (83.1, 95%CI: 74.9–89.0, I 2 = 90%) as compared to a single dose (69.3, 52.4–82.3, I 2 = 95%). The odds of seroconversion were lower in IMIDs as compared to healthy controls (0.05, 0.02–0.13, I 2 = 21%). The seroconversion rates in patients with inflammatory bowel disease (95.2, 95%CI: 92.6–96.9, I 2 = 0%), spondyloarthropathy (95.6, 95% CI: 83.4–98.9, I 2 = 35%), and systemic lupus erythematosus (90.7, 95%CI: 85.4–94.2, I 2 = 0%) were higher as compared to rheumatoid arthritis (79.5, 95% CI: 65.1–88.9, I 2 = 85%), and vasculitis (70.5, 95% CI: 52.9–83.5, I 2 = 51%). The seroconversion rates following double dose of mRNA were excellent (>90%) in those on anti-tumour necrosis factor (TNF), anti-integrin (vedolizumab), anti-IL 17 (secukinumab), anti-IL6 (Tocilizumab) and anti-IL12/23 (Ustekinumab) therapies but attenuated (<70%) in patients on anti-CD20 (Rituximab) or anti-cytotoxic T lymphocyte associated antigen (CTLA-4) therapies (Abatacept). The seroconversion rates were good (70–90%) with steroids, hydroxychloroquine, JAK inhibitors, mycophenolate mofetil and leflunomide. Combination of anti-TNF with immunomodulators (azathioprine, 6-meracptopurine, methotrexate) resulted in an attenuated vaccine response as compared to anti-TNF monotherapy. Conclusion Seroconversion rates after SARS-CoV-2 vaccination are lower in patients with IMIDs. Certain therapies (anti-TNF, anti-integrin, anti-IL 17, anti-IL6, anti-12/23) do not impact seroconversion rates while others (anti-CD20, anti-CTLA-4) result in poorer responses.