Effects of Potent Neutralizing Antibodies from Convalescent Plasma in Patients Hospitalized for Severe SARS-CoV-2 Infection. (preprint)

Convalescent plasma could be an inexpensive and widely available treatment for COVID-19 patients but reports on effectiveness are inconclusive. We collected convalescent plasma from donors with high titers of neutralizing anti-SARS-CoV-2 antibodies effectively blocking SARS-CoV-2 infection in vitro. In a randomized clinical trial of 86 COVID-19 patients, no overall clinical benefit of 300 mL convalescent plasma was found in patients hospitalized for COVID-19 in the Netherlands. Using a comprehensive translational approach, we unraveled the virological and immunological responses following plasma treatment which helps to understand which COVID-19 patients may benefit from this therapy and should be the focus of future studies. Convalescent plasma treatment in this patient group did not improve survival, had no effect on the clinical course of disease, nor did plasma enhance viral clearance in the respiratory tract, influence anti-SARS-CoV-2 antibody development or serum proinflammatory cytokines levels. The vast majority of patients already had potent neutralizing anti-SARS-CoV-2 antibodies at hospital admission and at comparable titers as the carefully selected plasma donors. Together, these data indicate that the variable effectivity observed in trials on convalescent plasma for COVID-19 may be explained by the timing of treatment and varying levels of preexisting anti-SARS-CoV-2 immunity in patients. It also substantiates that convalescent plasma should be studied as early as possible in the disease course or at least preceding the start of an autologous humoral response. Trial registration: Clinicaltrials.gov: NCT04342182

Shedding of infectious virus in hospitalized patients with coronavirus disease-2019 (COVID-19): duration and key determinants (preprint)

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; p<0,001) as independently associated with isolation of infectious SARS-CoV-2 from the respiratory tract. A serum neutralizing antibody titre of at least 1:20 (OR of 0,01 (CI 0,003-0,08; p<0,001) was independently associated with non-infectious SARS-CoV-2. InterpretationInfection 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 contextO_ST_ABSEvidence before this studyC_ST_ABSWe 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; p<0,001). A serum neutralizing antibody titre of at least 1:20 (OR of 0,01 (CI 0,003-0,08; p<0,001) was independently associated with non-infectious SARS-CoV-2. Implications 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.

Towards the next phase: evaluation of serological assays for diagnostics and exposure assessment. (preprint)

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.