SARS-CoV-2 Contamination on Healthy Individuals' Hands in Community Settings During the COVID-19 Pandemic

TL;DR

This study found very low levels of SARS-CoV-2 on the hands of healthy people, with no viable viruses detected, suggesting minimal risk of contact transmission in community settings.

Contribution

The study provides new evidence on the low risk of SARS-CoV-2 hand contamination and contact transmission in community settings.

Findings

SARS-CoV-2 RNA was detected in 0.32% of hand swab samples from healthy individuals.

No viable SARS-CoV-2 viruses were found in the RNA-positive samples.

The risk of contact transmission via hands in community settings appears to be extremely rare.

Abstract

Introduction

Hand hygiene is an infection control measure for COVID-19 in our daily lives; however, the contamination levels of SARS-CoV-2 in the hands of healthy individuals remain unclear. Thus, we aimed to evaluate SARS-CoV-2 contamination levels by detecting viral RNA and viable viruses in samples obtained from the hands of 925 healthy individuals.

Methods

Swab samples were collected from the palms and fingers of healthy participants, including office workers, public officers, university students, university faculty and staff, and hospital staff between December 2022 and March 2023. The collected swab samples were analyzed using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) for SARS-CoV-2 RNA detection. Viral RNA-positive samples were subjected to plaque assay to detect viable viruses.

Results

We collected 1,022 swab samples from the hands of healthy participants. According to the criteria for data collection, 97 samples were excluded, and 925 samples were analyzed using RT-qPCR. SARS-CoV-2 RNA was detected in three of the 925 samples. The viral RNA detection rate was 0.32% (3/925), and the viral RNA copy numbers ranged from 5.0×103 to 1.7×105 copies/mL. The RT-qPCR-positive samples did not contain viable viruses, as confirmed by the plaque assay results.

Conclusions

The detection rate of SARS-CoV-2 RNA from the hands of healthy individuals was extremely low, and no viable viruses were detected. These results suggest that the risk of contact transmission via hands in a community setting is extremely rare.