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ImportanceSARS-CoV-2 viral trajectory has not been well-characterized in documented incident infections. These data will inform SARS-CoV-2 natural history, transmission dynamics, prevention practices, and therapeutic development. ObjectiveTo prospectively characterize early SARS-CoV-2 viral shedding in persons with incident infection. DesignProspective cohort study. SettingSecondary data analysis from a multicenter study in the U.S. ParticipantsThe samples derived from a randomized controlled trial of 829 community-based asymptomatic participants recently exposed (<96 hours) to persons with SARS-CoV-2. Participants collected daily mid-turbinate swabs for SARS-CoV-2 detection by polymerase-chain-reaction and symptom diaries for 14-days. Persons with negative swab for SARS-CoV-2 at baseline who developed infection during the study were included in the analysis. ExposureLaboratory-confirmed SARS-CoV-2 infection. Main outcomes and measuresThe observed SARS-CoV-2 viral shedding characteristics were summarized and shedding trajectories were examined using a piece-wise linear mixed-effects modeling. Whole viral genome sequencing was performed on samples with cycle threshold (Ct)<34. ResultsNinety-seven persons (57% women, median age 37-years) developed incident infections during 14-days of follow-up. Two-hundred fifteen sequenced samples were assigned to 15 lineages that belonged to the G614 variant. Forty-two (43%), 18(19%), and 31(32%) participants had viral shedding for 1 day, 2-6 days, and [≥]7 days, with median peak viral load Ct of 38.5, 36.7, and 18.3, respectively. Six (6%) participants had 1-6 days of observed viral shedding with censored duration. The peak average viral load was observed on day 3 of viral shedding. The average Ct value was lower, indicating higher viral load, in persons reporting COVID-19 symptoms than asymptomatic. Using the statistical model, the median time from shedding onset to peak viral load was 1.4 days followed by a median of 9.7 days before clearance. Conclusions and RelevanceIncident SARS-CoV-2 G614 infection resulted in a rapid viral load peak followed by slower decay and positive correlation between peak viral load and shedding duration; duration of shedding was heterogeneous. This longitudinal evaluation of the SARS-CoV-2 G614 variant with frequent molecular testing may serve as a reference for comparing emergent viral lineages to inform clinical trial designs and public health strategies to contain the spread of the virus. KEY POINTSO_ST_ABSQuestionC_ST_ABSWhat are the early SARS-CoV-2 G614 viral shedding characteristics in persons with incident infection? FindingsIn this prospective cohort of 97 community-based participants who collected daily mid-turbinate swabs for SARS-CoV-2 detection after recent exposure to SARS-CoV-2, viral trajectory was characterized by a rapid peak followed by slower decay. Peak viral load correlated positively with symptoms. The duration of shedding was heterogeneous. MeaningA detailed description of the SARS-CoV-2 G614 viral shedding trajectory serves as baseline for comparison to new viral variants of concern and inform models for the planning of clinical trials and transmission dynamics to end this pandemic.
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With the availability of widespread SARS-CoV-2 vaccination, high-throughput quantitative anti-spike serological testing will likely become increasingly important. Here, we investigated the performance characteristics of the recently FDA authorized semi-quantitative anti-spike AdviseDx SARS-CoV-2 IgG II assay compared to the FDA authorized anti-nucleocapsid Abbott Architect SARS-CoV-2 IgG, Roche elecsys Anti-SARS-CoV-2-S, EuroImmun Anti-SARS-CoV-2 ELISA, and GenScript surrogate virus neutralization assays and examined the humoral response associated with vaccination, natural protection, and breakthrough infection. The AdviseDx assay had a clinical sensitivity at 14 days post-symptom onset or 10 days post PCR detection of 95.6% (65/68, 95% CI: 87.8-98.8%) with two discrepant individuals seroconverting shortly thereafter. The AdviseDx assay demonstrated 100% positive percent agreement with the four other assays examined using the same symptom onset or PCR detection cutoffs. Using a recently available WHO International Standard for anti-SARS-CoV-2 antibody, we provide assay unit conversion factors to international units for each of the assays examined. We performed a longitudinal survey of healthy vaccinated individuals, finding median AdviseDx immunoglobulin levels peaked seven weeks post-first vaccine dose at approximately 4,000 IU/mL. Intriguingly, among the five assays examined, there was no significant difference in antigen binding level or neutralizing activity between two seropositive patients protected against SARS-CoV-2 infection in a previously described fishing vessel outbreak and five healthcare workers who experienced vaccine breakthrough of SARS-CoV-2 infection - all with variants of concern. These findings suggest that protection against SARS-CoV-2 infection cannot currently be predicted exclusively using in vitro antibody assays against wildtype SARS-CoV-2 spike. Further work is required to establish protective correlates of protection for SARS-CoV-2 infection.
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Anti-SARS-CoV-2 antibodies have been described, but correlation with virologic outcomes is limited. Here, we find anti-SARS-CoV-2 IgG to be associated with reduced viral load. High viral loads were rare in individuals who had seroconverted. Higher viral load on admission was associated with increased 30-day mortality (OR 4.20 [95% CI: 1.62-10.86]).
