Asymptomatic SARS-CoV-2 infection among research personnel: Study

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A recent research paper published in the journal Public Library of Science (PLOS) ONE analyzed asymptomatic coronavirus disease 2019 (COVID-19) in personnel engaged in academic study. 

Study: A prospective study of asymptomatic SARS-CoV-2 infection among individuals involved in academic research under limited operations during the COVID-19 pandemic. Image Credit: Gorodenkoff / Shutterstock


The COVID-19 pandemic has impacted research initiatives across university campuses. Early in the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pandemic, the danger of transmission from asymptomatic COVID-19 patients was unknown. This made it critical to keep an eye on infection in the workplace. 

Non-essential research operations were terminated in March 2020, and most researchers, support personnel, and trainees were sent home. Many universities, however, began bringing research employees back to campuses in the mid-2020s, following updated safety standards and using various ways to test for SARS-CoV-2 to detect infections in the workplace.

Previous studies have shown that asymptomatic SARS-CoV-2 patients shed the virus for fewer days than symptomatic patients. This might harm the efficiency of routine SARS-CoV-2 testing procedures to detect acute infections among asymptomatic persons in the workplace. Furthermore, existing papers depicted that pre-symptomatic people were infectious, with virus shedding occurring 48 hours before symptom onset. However, the data on SARS-CoV-2 seroprevalence among university populations remain scarce.

About the study

The primary goal of the present paper was to explore the degree of SARS-CoV-2 incidence and seroprevalence within the research community at the campus of an academic university, the University of North Carolina at Chapel Hill (UNC-CH), under constrained operations. The researchers conducted a longitudinal cohort assessment of 910 university research personnel on campus from July to December 2020. These research faculty, employees, and students visited the UNC-CH campus at minimum a day every week within the specified timeframe. 

All people who received funding from the research grants were requested to enroll in the present study. The subjects submitted consent electronically before enrollment in the investigation. Individuals who were concurrently involved in a SARS-CoV-2 vaccine trial during the research period were excluded from the current analysis.

The team performed routine COVID-19 reverse transcriptase-polymerase chain reaction (RT-PCR) testing, serology, and risk factors surveys. They used a laboratory-based SARS-CoV-2 spike (S) N-terminal domain (NTD) assay, a standard nucleocapsid (N) platform assay, and an in-house S receptor-binding domain (RBD) assay. The investigators calculated the cumulative incidence and prevalence of SARS-CoV-2 seroconversion with 95% confidence intervals using the reverse of the Kaplan-Meier estimator. 

Results and discussions

According to the study results, RT-PCR analysis discovered just six SARS-CoV-2-positive cases, whereas serology showed a 3.6% COVID-19 incidence over the approximately three-month trial. Initial SARS-CoV-2 seroprevalence was 0.5% based on the N Abbott SARS-CoV-2 immunoglobulin G (IgG) test. However, it rose to 5.4% utilizing an in-house S RBD IgG enzyme-linked immunosorbent assay (ELISA) analysis. While this university cohort reported generally robust compliance with SARS-CoV-2 public health standards, the investigators suggested that seroconversion was linked to gathering in clusters of 10 or more in public and at work. 

The authors believed that the short duration of SARS-CoV-2 shedding in asymptomatic persons and the employed bi-weekly RT-PCR screening likely missed infections occurred during follow-up. Thus, the team suggested that a more regular COVID-19 testing schedule was required to identify asymptomatic infections.

The investigators discovered very poor concordance between serological testing approaches when comparing anti-N with the in-house, lab-based ELISA and the Abbott platform for RBD. These findings imply that the target antigen of the selected assay was crucial for detecting asymptomatic and mild COVID-19 cases, which might explain the observed disparities.

The authors stated that the SARS-CoV-2 seroprevalence was probably lower in this sample cohort of university personnel involved in campus research than in the overall North Carolina population. Despite increased COVID-19 cases in North Carolina over the same months, the SARS-CoV-2 infection incidence remained low during follow-up in the present investigation.


The study findings showed that the incidence and prevalence of COVID-19 were poor among the research personnel and students engaged in an academic study under limited operations during 2020 at the UNC-CH campus. COVID-19 preventative measures were followed to a high degree in the workplace. Nevertheless, the investigators reported that the variations in SARS-CoV-2 target antigens of serological analysis offered different estimates.

The authors pointed out that additional studies are required to determine the most effective serological testing procedures in both COVID-19 vaccinated and unvaccinated populations. The team stated that asymptomatic people must undergo frequent SARS-CoV-2 RT-PCR testing to detect acute infections. These data also highlight the significance of recurrent COVID-19 serosurveys in tracking subclinical SARS-CoV-2 infections.

Source: News Medical

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