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The world is entering a new era of the COVID-19 pandemic in which there is an increasing call for reliable antibody testing. To support decision making on the deployment of serology for either population screening or diagnostics, we present a detailed comparison of serological COVID-19 assays. We show that among the selected assays there is a wide diversity in assay performance in different scenarios and when correlated to virus neutralizing antibodies. The Wantai ELISA detecting total immunoglobulins against the receptor binding domain of SARS CoV-2, has the best overall characteristics to detect functional antibodies in different stages and severity of disease, including the potential to set a cut-off indicating the presence of protective antibodies. The large variety of available serological assays requires proper assay validation before deciding on deployment of assays for specific applications., SARS-CoV-2 is causing a global pandemic in which the implementation of serology can support decision making in different scenarios. Here, the authors compare the outcome of eight commercially available assays to virus neutralization and discuss their use in diagnostics and exposure assessment of SARS-CoV-2.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is the cause of coronavirus disease 2019 (COVID-19). Little is known about the interplay between preexisting immunity to endemic seasonal coronaviruses and the development of a SARS-CoV-2–specific IgG response. We investigated the kinetics, breadth, magnitude, and level of cross-reactivity of IgG antibodies against SARS-CoV-2 and heterologous seasonal and epidemic coronaviruses at the clonal level in patients with mild or severe COVID-19 as well as in disease control patients. We assessed antibody reactivity to nucleocapsid and spike antigens and correlated this IgG response to SARS-CoV-2 neutralization. Patients with COVID-19 mounted a mostly type-specific SARS-CoV-2 response. Additionally, IgG clones directed against a seasonal coronavirus were boosted in patients with severe COVID-19. These boosted clones showed limited cross-reactivity and did not neutralize SARS-CoV-2. These findings indicate a boost of poorly protective CoV-specific antibodies in patients with COVID-19 that correlated with disease severity, revealing “original antigenic sin.”

Summary Background The Middle East respiratory syndrome coronavirus (MERS-CoV) causes a respiratory disease with a case fatality rate of up to 35%. Given its potential to cause a public health emergency and the absence of efficacious drugs or vaccines, MERS is one of the WHO priority diseases warranting urgent research and development of countermeasures. We aimed to assess safety and tolerability of an anti-MERS-CoV modified vaccinia virus Ankara (MVA)-based vaccine candidate that expresses the MERS-CoV spike glycoprotein, MVA-MERS-S, in healthy adults. Methods This open-label, phase 1 trial was done at the University Medical Center Hamburg-Eppendorf (Hamburg, Germany). Participants were healthy men and women aged 18–55 years with no clinically significant health problems as determined during medical history and physical examination, a body-mass index of 18·5–30·0 kg/m2 and weight of more than 50 kg at screening, and a negative pregnancy test for women. A key exclusion criterion was a previous MVA vaccination. For the prime immunisation, participants received doses of 1 × 107 plaque-forming unit (PFU; low-dose group) or 1 × 108 PFU (high-dose group) MVA-MERS-S intramuscularly. A second identical dose was administered intramuscularly as a booster immunisation 28 days after first injection. As a control group for immunogenicity analyses, blood samples were drawn at identical study timepoints from six healthy adults, who did not receive any injections. The primary objectives of the study were safety and tolerability of the two dosage levels and reactogenicity after administration. Immunogenicity was assessed as a secondary endpoint by ELISA and neutralisation tests. T-cell immunity was evaluated by interferon-γ-linked enzyme-linked immune absorbent spot assay. All participants who were vaccinated at least once were included in the safety analysis. Immunogenicity was analysed in the participants who completed 6 months of follow-up. This trial is registered with ClinicalTrials.gov , NCT03615911 , and EudraCT, 2014-003195-23 Findings From Dec 17, 2017, to June 5, 2018, 26 participants (14 in the low-dose group and 12 in the high-dose group) were enrolled and received the first dose of the vaccine according to their group allocation. Of these, 23 participants (12 in the low-dose group and 11 in the high-dose group) received a second dose of MVA-MERS-S according to their group allocation after a 28-day interval and completed follow-up. Homologous prime–boost immunisation with MVA-MERS-S revealed a benign safety profile with only transient mild-to-moderate reactogenicity. Participants had no severe or serious adverse events. 67 vaccine-related adverse events were reported in ten (71%) of 14 participants in the low-dose group, and 111 were reported in ten (83%) of 12 participants in the high-dose group. Solicited local reactions were the most common adverse events: pain was observed in 17 (65%; seven in the low-dose group vs ten in the high-dose group) participants, swelling in ten (38%; two vs eight) participants, and induration in ten (38%; one vs nine) participants. Headaches (observed in seven participants in the low-dose group vs nine in the high-dose group) and fatigue or malaise (ten vs seven participants) were the most common solicited systemic adverse events. All adverse events resolved swiftly (within 1–3 days) and without sequelae. Following booster immunisation, nine (75%) of 12 participants in the low-dose group and 11 (100%) participants in the high-dose group showed seroconversion using a MERS-CoV S1 ELISA at any timepoint during the study. Binding antibody titres correlated with MERS-CoV-specific neutralising antibodies (Spearman's correlation r=0·86 [95% CI 0·6960–0·9427], p=0·0001). MERS-CoV spike-specific T-cell responses were detected in ten (83%) of 12 immunised participants in the low-dose group and ten (91%) of 11 immunised participants in the high-dose group. Interpretation Vaccination with MVA-MERS-S had a favourable safety profile without serious or severe adverse events. Homologous prime–boost immunisation induced humoral and cell-mediated responses against MERS-CoV. A dose–effect relationship was demonstrated for reactogenicity, but not for vaccine-induced immune responses. The data presented here support further clinical testing of MVA-MERS-S in larger cohorts to advance MERS vaccine development. Funding German Center for Infection Research.

A new coronavirus, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has recently emerged to cause a human pandemic. Although molecular diagnostic tests were rapidly developed, serologic assays are still lacking, yet urgently needed. Validated serologic assays are needed for contact tracing, identifying the viral reservoir, and epidemiologic studies. We developed serologic assays for detection of SARS-CoV-2 neutralizing, spike protein–specific, and nucleocapsid-specific antibodies. Using serum samples from patients with PCR-confirmed SARS-CoV-2 infections, other coronaviruses, or other respiratory pathogenic infections, we validated and tested various antigens in different in-house and commercial ELISAs. We demonstrated that most PCR-confirmed SARS-CoV-2–infected persons seroconverted by 2 weeks after disease onset. We found that commercial S1 IgG or IgA ELISAs were of lower specificity, and sensitivity varied between the 2 assays; the IgA ELISA showed higher sensitivity. Overall, the validated assays described can be instrumental for detection of SARS-CoV-2–specific antibodies for diagnostic, seroepidemiologic, and vaccine evaluation studies.

Middle East respiratory syndrome coronavirus (MERS-CoV) infections in humans can cause asymptomatic to fatal lower respiratory lung disease. Despite posing a probable risk for virus transmission, asymptomatic to mild infections can go unnoticed; a lack of seroconversion among some PCR-confirmed cases has been reported. We found that a MERS-CoV spike S1 protein-based ELISA, routinely used in surveillance studies, showed low sensitivity in detecting infections among PCR-confirmed patients with mild clinical symptoms and cross-reactivity of human coronavirus OC43-positive serum samples. Using in-house S1 ELISA and protein microarray, we demonstrate that most PCR-confirmed MERS-CoV case-patients with mild infections seroconverted; nonetheless, some of these samples did not have detectable levels of virus-neutralizing antibodies. The use of a sensitive and specific serologic S1-based assay can be instrumental in the accurate estimation of MERS-CoV prevalence.

Optimal vaccines are needed for sustained suppression of SARS‐CoV‐2 and other novel coronaviruses. Here, we developed a recombinant type 5 adenovirus vector encoding the gene for the SARS‐CoV‐2 S1 subunit antigen (Ad5.SARS‐CoV‐2‐S1) for COVID‐19 immunization and evaluated its immunogenicity in mice. A single immunization with Ad5.SARS‐CoV‐2‐S1 via S.C. injection or I.N delivery induced robust antibody and cellular immune responses. Vaccination elicited significant S1‐specific IgG, IgG1, and IgG2a endpoint titers as early as 2 weeks, and the induced antibodies were long lasting. I.N. and S.C. administration of Ad5.SARS‐CoV‐2‐S1 produced S1‐specific GC B cells in cervical and axillary LNs, respectively. Moreover, I.N. and S.C. immunization evoked significantly greater antigen‐specific T‐cell responses compared to unimmunized control groups with indications that S.C. injection was more effective than I.N. delivery in eliciting cellular immune responses. Mice vaccinated by either route demonstrated significantly increased virus‐specific neutralization antibodies on weeks 8 and 12 compared to control groups, as well as BM antibody forming cells (AFC), indicative of long‐term immunity. Thus, this Ad5‐vectored SARS‐CoV‐2 vaccine candidate showed promising immunogenicity following delivery to mice by S.C. and I.N. routes of administration, supporting the further development of Ad‐based vaccines against COVID‐19 and other infectious diseases for sustainable global immunization programs., Vaccine development against SARS‐CoV‐2 addresses the ongoing challenges posed by this pathogen and ensures preparedness for future outbreaks of coronaviruses. Subcutaneous or intranasal administration of Ad5.SARS‐CoV‐2 S1 results in multifaceted immune responses in mice, including GCs and long‐lived antibody forming cells, representing an attractive COVID‐19 vaccination strategy.

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic is continuing to disrupt personal lives, global healthcare systems, and economies. Hence, there is an urgent need for a vaccine that prevents viral infection, transmission, and disease. Here, we present a two-component protein-based nanoparticle vaccine that displays multiple copies of the SARS-CoV-2 spike protein. Immunization studies show that this vaccine induces potent neutralizing antibody responses in mice, rabbits, and cynomolgus macaques. The vaccine-induced immunity protects macaques against a high-dose challenge, resulting in strongly reduced viral infection and replication in the upper and lower airways. These nanoparticles are a promising vaccine candidate to curtail the SARS-CoV-2 pandemic., Graphical Abstract, Brouwer et al. present preclinical evidence in support of a COVID-19 vaccine candidate, designed as a self-assembling two-component protein nanoparticle displaying multiple copies of the SARS-CoV-2 spike protein, which induces strong neutralizing antibody responses and protects from high-dose SARS-CoV-2 challenge.

The severe acute respiratory syndrome (SARS) coronavirus 2 (SARS-CoV-2) has emerged as the infectious agent causing the pandemic coronavirus disease 2019 (COVID-19) with dramatic consequences for global human health and economics. Previously, we reached clinical evaluation with our vector vaccine based on vaccinia virus MVA against the Middle East respiratory syndrome coronavirus (MERS-CoV), which causes an infection in humans similar to SARS and COVID-19. Here, we describe the construction and preclinical characterization of a recombinant MVA expressing full-length SARS-CoV-2 spike (S) protein (MVA-SARS-2-S). Genetic stability and growth characteristics of MVA-SARS-2-S, plus its robust synthesis of S antigen, make it a suitable candidate vaccine for industrial scale production. Vaccinated mice produced S antigen-specific CD8+ T cells and serum antibodies binding to S glycoprotein that neutralized SARS-CoV-2. Prime-boost vaccination with MVA-SARS-2-S protected mice sensitized with a human ACE2-expressing adenovirus from SARS-CoV-2 infection. MVA-SARS-2-S is currently being investigated in a phase I clinical trial as aspirant for developing a safe and efficacious vaccine against COVID-19.Significance StatementThe highly attenuated vaccinia virus MVA is licensed as smallpox vaccine, and as vector it is a component of the approved Adenovirus-MVA-based prime-boost vaccine against Ebola virus disease. Here we provide results from testing the COVID-19 candidate vaccine MVA-SARS-2-S, a poxvirus-based vector vaccine that proceeded to clinical evaluation. When administered by intramuscular inoculation, MVA-SARS-2-S expresses and safely delivers the full-length SARS-CoV-2 spike (S) protein, inducing balanced SARS-CoV-2-specific cellular and humoral immunity, and protective efficacy in vaccinated mice. Substantial clinical experience has already been gained with MVA vectors using homologous and heterologous prime-boost applications, including the immunization of children and immunocompromised individuals. Thus, MVA-SARS-2-S represents an important resource for developing further optimized COVID-19 vaccines.

Key questions in COVID-19 are the duration and determinants of infectious virus shedding. Here, we report that infectious virus shedding is detected by virus cultures in 23 of the 129 patients (17.8%) hospitalized with COVID-19. The median duration of shedding infectious virus is 8 days post onset of symptoms (IQR 5–11) and drops below 5% after 15.2 days post onset of symptoms (95% confidence interval (CI) 13.4–17.2). Multivariate analyses identify viral loads above 7 log10 RNA copies/mL (odds ratio [OR] of 14.7 (CI 3.57-58.1; p, Duration of infectious SARS-CoV-2 shedding is an important measure for improved disease control. Here, the authors use virus cultures of respiratory tract samples from COVID-19 patients and observe a median shedding duration of 8 days and a drop below 5% after 15,2 days post onset of symptoms.

The coronavirus spike glycoprotein, located on the virion surface, is the key mediator of cell entry. As such, it is an attractive target for the development of protective antibodies and vaccines. Here we describe two human monoclonal antibodies, 1.6C7 and 28D9, that display a remarkable cross-reactivity against distinct species from three Betacoronavirus subgenera, capable of binding the spike proteins of SARS-CoV and SARS-CoV-2, MERS-CoV and the endemic human coronavirus HCoV-OC43. Both antibodies, derived from immunized transgenic mice carrying a human immunoglobulin repertoire, blocked MERS-CoV infection in cells, whereas 28D9 also showed weak cross-neutralizing potential against HCoV-OC43, SARS-CoV and SARS-CoV-2 in a neutralization-sensitive virus pseudotyping system, but not against authentic virus. Both cross-reactive monoclonal antibodies were found to target the stem helix in the spike protein S2 fusion subunit which, in the prefusion conformation of trimeric spike, forms a surface exposed membrane-proximal helical bundle, that is antibody-accessible. We demonstrate that administration of these antibodies in mice protects from a lethal MERS-CoV challenge in both prophylactic and/or therapeutic models. Collectively, these antibodies delineate a conserved, immunogenic and vulnerabe site on the spike protein which spurs the development of broad-range diagnostic, preventive and therapeutic measures against coronaviruses., The project was co-financed by a grant from the Zoonotic Anticipation and Preparedness Initiative [ZAPI project; Innovative Medicines Initiative (IMI) grant agreement no. 115760], with the assistance and financial support of IMI and the European Commission, and in-kind contributions from European Federation of Pharmaceutical Industries and Associations partners. The collaboration project is cofunded by the PPP Allowance made available by Health~Holland, Top Sector Life Sciences & Health, to stimulate public-private partnerships. This study was also partially financed by grants from the Ministry of Science and Innovation of Spain (BIO2016-75549-R AEI/FEDER, UE) and NIH (2PO1AIO6O699). The mice used to generate the mAbs produced in this study were provided by Harbour Antibodies BV, a daughter company of Harbour Biomed (http://www.harbourbiomed.com). Chunyan Wang was supported by a grant from the China Scholarship Council.

Severe acquired respiratory syndrome coronavirus-2 (SARS-CoV-2) is the cause of coronavirus disease (COVID-19). In severe COVID-19 cases, higher antibody titers against seasonal coronaviruses have been observed than in mild cases. To investigate antibody cross-reactivity as potential explanation for severe disease, we determined the kinetics, breadth, magnitude and level of cross-reactivity of IgG against SARS-CoV-2 and seasonal CoV nucleocapsid and spike from 17 severe COVID-19 cases at the clonal level. Although patients mounted a mostly type-specific SARS-CoV-2 response, B-cell clones directed against seasonal CoV dominated and strongly increased over time. Seasonal CoV IgG responses that did not neutralize SARS-CoV-2 were boosted well beyond detectable cross-reactivity, particularly for HCoV-OC43 spike. These findings support a back-boost of poorly protective coronavirus-specific antibodies in severe COVID-19 patients that may negatively impact de novo SARS-CoV-2 immunity, reminiscent of original antigenic sin.

Effective clinical intervention strategies for COVID-19 are urgently needed. Although several clinical trials have evaluated the use of convalescent plasma containing virus-neutralizing antibodies, the effectiveness has not been proven. We show that hamsters treated with a high dose of human convalescent plasma or a monoclonal antibody were protected against weight loss showing reduced pneumonia and pulmonary virus replication compared to control animals. However, a ten-fold lower dose of convalescent plasma showed no protective effect. Thus, variable and relatively low levels of virus neutralizing antibodies in convalescent plasma may limit their use for effective antiviral therapy, favouring concentrated, purified (monoclonal) antibodies.

Understanding the coronavirus (CoV) antibody landscape in relation to disease and susceptibility is critical for modelling of steps in the next phase during the current covid-19 pandemic. In March 2020, during the first month of the epidemic in The Netherlands, we performed cross sectional studies at two time points amongst patients of the Erasmus Medical Centre in Rotterdam, to assess the presence of antibodies against seasonal human coronaviruses (OC43, 229E, NL63, HKU1), emerging zoonotic coronaviruses (SARS, MERS) and SARS-CoV-2 in nine different age groups. We observed minimal SARS-CoV-2 reactivity early March (0.7% of sera), increasing to 3.0%, four weeks later, suggesting probably undetected cases during this early phase of the epidemic. Antibody responses were mostly coronavirus species specific at young age, but possible cross-reactivity between human seasonal CoVs was observed with increasing age.

Structured abstract for full paperBackgroundAfter recovery from COVID-19, most patients have anti-SARS-CoV-2 neutralizing antibodies. Their convalescent plasma could be an inexpensive and widely available treatment for COVID-19.MethodsThe Convalescent-plasma-for-COVID (ConCOVID) study was a randomized trial comparing convalescent plasma with standard of care therapy in patients hospitalized for COVID-19 in the Netherlands. Patients were randomized 1:1 and received 300ml of plasma with anti-SARS-CoV-2 neutralizing antibody titers of at least 1:80. The primary endpoint was day-60 mortality and key secondary endpoints were hospital stay and WHO 8-point disease severity scale improvement on day 15.ResultsThe trial was halted prematurely after 86 patients were enrolled. Although symptomatic for only 10 days (IQR 6-15) at the time of inclusion, 53 of 66 patients tested had anti-SARS-CoV-2 antibodies at baseline. A SARS-CoV-2 plaque reduction neutralization test showed neutralizing antibodies in 44 of the 56 (79%) patients tested with median titers comparable to the 115 donors (1:160 vs 1:160, p=0.40). These observations caused concerns about the potential benefit of convalescent plasma in the study population and after discussion with the data safety monitoring board, the study was discontinued. No difference in mortality (p=0.95), hospital stay (p=0.68) or day-15 disease severity (p=0.58) was observed between plasma treated patients and patients on standard of care.ConclusionMost COVID-19 patients already have high neutralizing antibody titers at hospital admission. Screening for antibodies and prioritizing convalescent plasma to risk groups with recent symptom onset will be key to identify patients that may benefit from convalescent plasma. Clinicaltrials.gov:NCT04342182

Sites of vulnerability in SARS-CoV-2 Antibodies that neutralize severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) could be an important tool in treating coronavirus disease 2019 (COVID-19). Brouwer et al. isolated 403 monoclonal antibodies from three convalescent COVID-19 patients. They show that the patients had strong immune responses against the viral spike protein, a complex that binds to receptors on the host cell. A subset of antibodies was able to neutralize the virus. Competition and electron microscopy studies showed that these antibodies target diverse epitopes on the spike, with the two most potent targeting the domain that binds the host receptor. Science , this issue p. 643

BackgroundLong-term shedding of viral RNA in COVID-19 prevents timely discharge from the hospital or de-escalation of infection prevention and control practices. Key questions are the duration and determinants of infectious virus shedding. We assessed these questions using virus cultures of respiratory tract samples from hospitalized COVID-19 patients as a proxy for infectious virus shedding.MethodsClinical and virological data were obtained from 129 hospitalized COVID-19 patients (89 intensive care, 40 medium care). Generalized estimating equations were used to identify if viral RNA load, detection of viral subgenomic RNA, serum neutralizing antibody response, duration of symptoms, or immunocompromised status were predictive for a positive virus culture.FindingsInfectious virus shedding was detected in 23 of the 129 patients (17,8%). The median duration of shedding was 8 days post onset of symptoms (IQR 5 – 11) and the probability of detecting infectious virus dropped below 5% after 15,2 days post onset of symptoms (95% confidence interval (CI) 13,4 – 17,2). Multivariate analyses identified viral loads above 7 log10 RNA copies/mL (odds ratio [OR]; CI 14,7 (3,57-58,1; pInterpretationInfection prevention and control guidelines should take into account that patients with severe or critical COVID-19 may shed infectious virus for longer periods of time compared to what has been reported for in patients with mild COVID-19. Infectious virus shedding drops to undetectable levels below a viral RNA load threshold and once serum neutralizing antibodies are present, which warrants the use of quantitative viral RNA load assays and serological assays in test-based strategies to discontinue or de-escalate infection prevention and control precautions.Research in contextEvidence before this studyWe searched PubMed, bioRxiv, and medRxiv for articles that reported on shedding of infectious virus in COVID-19 patients using the search terms (“coronavirus” OR “SARS” OR “SARS-CoV-2” OR “COVID-19”) AND (“shedding” OR “infectivity” OR “infectious” OR “virus culture”) with no language or time restrictions. A detailed study on nine patients with mild COVID-19 reported that infectious virus could not be isolated after more than eight days of symptoms. The probability of isolating infectious virus was less than 5% when viral loads dropped below 6,51 Log10 RNA copies/mL. Similar results were obtained with a larger diagnostic sample set, but that study did not report on clinical parameters such as disease severity. Finally there is a report of a single patient shedding infectious virus up to 18 days after onset of symptoms. No published works were found on the shedding of infectious virus in patients with severe or critical COVID-19, and no published works were found on factors independently associated with shedding of infectious virus.Added value of this studyWe assessed the duration and determinants of infectious virus shedding in 129 patients with severe or critical COVID-19. The duration of infectious virus shedding ranged from 0 to 20 days post onset of symptoms (median 8 days, IQR 5 – 11). The probability of detecting infectious virus dropped below 5% after 15,2 days post onset of symptoms (95% confidence interval (CI) 13,4 – 17,2). Viral loads above 7 log10 RNA copies/mL were independently associated with detection of infectious SARS-CoV-2 from the respiratory tract (odds ratio [OR]; CI 14,7 (3,57-58,1; pImplications of all the available evidenceInfection prevention and control guidelines should take into account that patients with severe or critical COVID-19 may shed infectious virus for longer periods of time compared to what has been reported for in patients with mild COVID-19. Quantitative viral RNA load assays and serological assays should be used for test-based strategies to discontinue or de-escalate infection prevention and control precautions.

The world is entering a new era of the COVID-19 pandemic in which there is an increasing call for reliable antibody testing. To support decision making on the deployment of serology for either population screening or diagnostics, we present a comprehensive comparison of serological COVID-19 assays. We show that the assay detecting total immunoglobulins against the receptor binding domain of SARS CoV-2, had optimal characteristics for antibody detection in different stages of disease.

SARS-CoV-2 has been identified as the causative agent of a global outbreak of respiratory tract disease (COVID-19). In some patients the infection results in moderate to severe acute respiratory distress syndrome (ARDS), requiring invasive mechanical ventilation. High serum levels of IL-6 and an immune hyperresponsiveness referred to as a ‘cytokine storm’ have been associated with poor clinical outcome. Despite the large numbers of cases and deaths, information on the phenotype of SARS-CoV-2-specific T-cells is scarce. Here, we detected SARS-CoV-2-specific CD4+ and CD8+ T cells in 100% and 80% of COVID-19 patients, respectively. We also detected low levels of SARS-CoV-2-reactive T-cells in 20% of the healthy controls, not previously exposed to SARS-CoV-2 and indicative of cross-reactivity due to infection with ‘common cold’ coronaviruses. Strongest T-cell responses were directed to the surface glycoprotein (spike, S), and SARS-CoV-2-specific T-cells predominantly produced effector and Th1 cytokines, although Th2 and Th17 cytokines were also detected. Collectively, these data stimulate further studies into the role of T-cells in COVID-19, support vaccine design and facilitate the evaluation of vaccine candidate immunogenicity. Summary COVID-19 is associated with lymphopenia and ‘cytokine storm’, but there is a scarcity of information on specific cellular immune responses to SARS-CoV-2. Here, we characterized SARS-CoV-2-specific CD4+ and CD8+ T-cells in patients hospitalized with acute respiratory distress syndrome (ARDS).

A novel coronavirus, SARS-CoV-2, was recently identified in patients with an acute respiratory syndrome, COVID-19. To compare its pathogenesis with that of previously emerging coronaviruses, we inoculated cynomolgus macaques with SARS-CoV-2 or MERS-CoV and compared with historical SARS-CoV infections. In SARS-CoV-2-infected macaques, virus was excreted from nose and throat in absence of clinical signs, and detected in type I and II pneumocytes in foci of diffuse alveolar damage and mucous glands of the nasal cavity. In SARS-CoV-infection, lung lesions were typically more severe, while they were milder in MERS-CoV infection, where virus was detected mainly in type II pneumocytes. These data show that SARS-CoV-2 can cause a COVID-19-like disease, and suggest that the severity of SARS-CoV-2 infection is intermediate between that of SARS-CoV and MERS-CoV.One Sentence SummarySARS-CoV-2 infection in macaques results in COVID-19-like disease with prolonged virus excretion from nose and throat in absence of clinical signs.

Peptide pool stimulation enables longitudinal analysis of SARS-CoV-2-specific CD4+ and CD8+ T cells in ICU-admitted COVID-19 patients., SARS-CoV-2 has been identified as the causative agent of a global outbreak of respiratory tract disease (COVID-19). In some patients the infection results in moderate to severe acute respiratory distress syndrome (ARDS), requiring invasive mechanical ventilation. High serum levels of IL-6, IL-10 and an immune hyperresponsiveness referred to as a ‘cytokine storm’ have been associated with poor clinical outcome. Despite the large numbers of COVID-19 cases and deaths, information on the phenotype and kinetics of SARS-CoV-2-specific T cells is limited. Here, we studied 10 COVID-19 patients who required admission to an intensive care unit and detected SARS-CoV-2-specific CD4+ and CD8+ T cells in 10 out of 10 and 8 out of 10 patients, respectively. We also detected low levels of SARS-CoV-2-reactive T cells in 2 out of 10 healthy controls not previously exposed to SARS-CoV-2, which is indicative of cross-reactivity due to past infection with ‘common cold’ coronaviruses. The strongest T-cell responses were directed to the spike (S) surface glycoprotein, and SARS-CoV-2-specific T cells predominantly produced effector and Th1 cytokines, although Th2 and Th17 cytokines were also detected. Furthermore, we studied T-cell kinetics and showed that SARS-CoV-2-specific T cells are present relatively early and increase over time. Collectively, these data shed light on the potential variations in T-cell responses as a function of disease severity, an issue that is key to understanding the potential role of immunopathology in the disease, and also inform vaccine design and evaluation.

SARS-CoV-2, a coronavirus that emerged in late 2019, has spread rapidly worldwide, and information about the modes of transmission of SARS-CoV-2 among humans is critical to apply appropriate infection control measures and to slow its spread. Here we show that SARS-CoV-2 is transmitted efficiently via direct contact and via the air (via respiratory droplets and/or aerosols) between ferrets, 1 to 3 days and 3 to 7 days after exposure respectively. The pattern of virus shedding in the direct contact and indirect recipient ferrets is similar to that of the inoculated ferrets and infectious virus is isolated from all positive animals, showing that ferrets are productively infected via either route. This study provides experimental evidence of robust transmission of SARS-CoV-2 via the air, supporting the implementation of community-level social distancing measures currently applied in many countries in the world and informing decisions on infection control measures in healthcare settings., SARS-CoV-2 has rapidly spread globally and animal models to study transmission are needed. Here, Richard et al. show efficient transmission of SARS-CoV-2 between ferrets via direct contact and via the air, through respiratory droplets and/or aerosols.

Middle East respiratory syndrome coronavirus (MERS-CoV) still causes outbreaks despite public awareness and implementation of health care measures, such as rapid viral diagnosis and patient quarantine. Here we describe the current epidemiological picture of MERS-CoV, focusing on humans and animals affected by this virus and propose specific intervention strategies that would be appropriate to control MERS-CoV. One-third of MERS-CoV patients develop severe lower respiratory tract infection and succumb to a fatal outcome; these patients would require effective therapeutic antiviral therapy. Because of the lack of such intervention strategies, supportive care is the best that can be offered at the moment. Limiting viral spread from symptomatic human cases to health care workers and family members, on the other hand, could be achieved through prophylactic administration of MERS-CoV neutralizing antibodies and vaccines. To ultimately prevent spread of the virus into the human population, however, vaccination of dromedary camels – currently the only confirmed animal host for MERS-CoV – may be the best option to achieve a sustained drop in human MERS cases in time. In the end, a One Health approach combining all these different efforts is needed to tackle this zoonotic outbreak.

The emergence of the novel human coronavirus SARS-CoV-2 in Wuhan, China has caused a worldwide epidemic of respiratory disease (COVID-19). Vaccines and targeted therapeutics for treatment of this disease are currently lacking. Here we report a human monoclonal antibody that neutralizes SARS-CoV-2 (and SARS-CoV) in cell culture. This cross-neutralizing antibody targets a communal epitope on these viruses and may offer potential for prevention and treatment of COVID-19.

Middle East respiratory syndrome (MERS) is a respiratory disease caused by a zoonotic coronavirus (MERS-CoV). Camel handlers, including slaughterhouse workers and herders, are at risk of acquiring MERS-CoV infections. However, there is limited evidence of infections among camel handlers in Africa. The purpose of this study was to determine the presence of antibodies to MERS-CoV in high-risk groups in Kenya. Sera collected from 93 camel handlers, 58 slaughterhouse workers and 35 camel herders, were screened for MERS-CoV antibodies using ELISA and PRNT. We found four seropositive slaughterhouse workers by PRNT. Risk factors amongst the slaughterhouse workers included being the slaughterman (the person who cuts the throat of the camel) and drinking camel blood. Further research is required to understand the epidemiology of MERS-CoV in Africa in relation to occupational risk, with a need for additional studies on the transmission of MERS-CoV from dromedary camels to humans, seroprevalence and associated risk factors.

Thus far, no human MERS-CoV infections have been reported from Israel. Evidence for the circulation of MERS-CoV in dromedaries has been reported from almost all the countries of the Middle East, except Israel. Therefore, we aimed to analyze MERS-CoV infection in Israeli camelids, sampled between 2012 and 2017. A total of 411 camels, 102 alpacas and 19 llamas' sera were tested for the presence of antibodies to MERS-CoV. Our findings indicate a lower MERS-CoV seropositivity among Israeli dromedaries than in the surrounding countries, and for the first time naturally infected llamas were identified. In addition, nasal swabs of 661 camels, alpacas and lamas, obtained from January 2015 to December 2017, were tested for the presence of MERS-CoV RNA. All nasal swabs were negative, indicating no evidence for MERS-CoV active circulation in these camelids during that time period. Keywords: MERS coronavirus, Antibodies, Israel, Dromedary camels, Llamas, Alpacas

Coronaviruses in the Middle East Middle East respiratory syndrome coronavirus (MERS-CoV) causes severe acute respiratory illness and kills about a third of people infected. The virus is common in dromedary camels, which can be a source of human infections. In a survey for MERSCoV in over 1300 Saudi Arabian camels, Sabir et al. found that dromedaries share three coronavirus species with humans. Diverse MERS lineages in camels have caused human infections, which suggests that transfer among host species occurs quite easily. Haagmans et al. made a MERS-CoV vaccine for use in camels, using poxvirus as a vehicle. The vaccine significantly reduced virus excretion, which should help reduce the potential for transmission to humans, and conferred cross-immunity to camelpox infections. Science , this issue p. 81 , p. 77

Graphical abstract MERS-CoV vaccine target groups and the desired vaccine induced immunological response for each group. I: camels; II: camel contacts; III-A: healthcare workers and patients; III-B: house-hold contacts and MERS cases., Highlights • MERS-CoV vaccines for dromedary camels and their human contacts can potentially stop virus transmission in the community. • Both neutralizing antibody and T-cell responses are required for protection • MERS-CoV vaccines should aim at inducing (long term) mucosal immunity in the different target populations. • The spike protein induces both neutralizing antibodies and T-cell responses and is the main target of the current vaccine candidates. • Epitope-based vaccines, focusing at (cross)-protective epitopes, could induce higher and/or broader responses., Middle East respiratory syndrome coronavirus (MERS-CoV) is a cause of severe respiratory infection in humans, specifically the elderly and people with comorbidities. The re-emergence of lethal coronaviruses calls for international collaboration to produce coronavirus vaccines, which are still lacking to date. Ongoing efforts to develop MERS-CoV vaccines should consider the different target populations (dromedary camels and humans) and the correlates of protection. Extending on our current knowledge of MERS, vaccination of dromedary camels to induce mucosal immunity could be a promising approach to diminish MERS-CoV transmission to humans. In addition, it is equally important to develop vaccines for humans that induce broader reactivity against various coronaviruses to be prepared for a potential next CoV outbreak.