Trajectory of viral load in a prospective population-based cohort with incident SARS-CoV-2 G614 infection
Authors: Stankiewicz Karita Helen C. , Dong Tracy Q. , Johnston Christine , Neuzil Kathleen M. , Paasche-Orlow Michael K. , Kissinger Patricia J. , Bershteyn Anna , Thorpe Lorna E. , Deming Meagan , Kottkamp Angelica , Laufer Miriam , Landovitz Raphael J. , Luk Alfred , Hoffman Risa , Roychoudhury Pavitra , Magaret Craig A. , Grenninger Alexander L. , Huang Meei-Li , Jerome Keith R. , Wener Mark , Celum Connie , Chu Helen Y. , Baeten Jared M. , Wald Anna , Barnabas Ruanne V. , Brown Elizabeth R. ,   the Hydroxychloroquine COVID-19 PEP Study Team
Published: August 2021

Importance

SARS-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.

Objective

To prospectively characterize early SARS-CoV-2 viral shedding in persons with incident infection.

Design

Prospective cohort study.

Setting

Secondary data analysis from a multicenter study in the U.S.

Participants

The 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.

Exposure

Laboratory-confirmed SARS-CoV-2 infection.

Main outcomes and measures

The 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.

Results

Ninety-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 Relevance

Incident 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 POINTS

Question

What are the early SARS-CoV-2 G614 viral shedding characteristics in persons with incident infection?

Findings

In 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.

Meaning

A 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.