Characteristics of Asymptomatic COVID-19 In SARS-COV-2 Vaccine Trial Screening Participants

We conducted a Phase I SARS-CoV-2 vaccine trial in March 2022. During the screening, we identified a significant number of asymptomatic COVID-19 cases among the candidate participants. We aimed to highlight the clinical characteristics among these asymptomatic individuals as compared to subjects negative for SARS-CoV-2.

This observational study was conducted during participant screening for a Phase I SARS-CoV-2 vaccine trial in Jepara and Mranggen districts in Central Java, Semarang, Indonesia. Participants who reported no symptoms associated with COVID-19, confirmed by physical examinations, were included. Data on laboratory markers were documented. An asymptomatic case was defined as showing no clinical symptoms and signs of SARS-CoV-2 infection with a positive SARS-CoV-2 RT-PCR result. Individuals who tested negative for SARS-CoV-2 were included for comparison. A chi-square test was employed to assess the differences between the two groups, with a p-value <0.05 is considered significant.

A total of 219 participants were screened and included. One hundred and six participants (48.4%) had positive SARS-CoV-2 RT-PCR results, with mean Ct values of 28.29 +/- 6.74 for the helicase gene. There was no significant difference in demographic characteristics, physical examination, and laboratory findings (p-value >0.05) among individuals with positive and negative SARS-CoV-2.

In our vaccine trial screening phase, almost half were ineligible due to having asymptomatic SARS-CoV-2 infections. In addition, it is necessary that people with asymptomatic COVID-19 infection still need to be concerned because they have the same transmission potential.