The Environmental Stability of SARS-CoV-2 Variants Omicron BA.1 and BA.5 on the Surfaces of Widely Used Transport Packaging Materials

Abstract

The increased transmissibility of SARS-CoV-2 variants of concern (VOCs) has raised questions regarding the environmental stability of these viruses. Although a prolonged survival time has been reported for SARS-CoV-2, how long new variants can persist on contaminated surfaces and how environmental factors affect the persistence time are not fully characterized. The present study provides a comprehensive assessment of the stability of Omicron variants BA.1 and BA.5, which are currently circulating strains, on the surfaces of widely used transport packaging materials. By monitoring viable virus detection over a 7-day period under different environmental conditions, it was found that the environmental stability of SARS-CoV-2 Omicron variants depended heavily on the surface type, temperature, and virus concentration. In addition, virus nucleic acid exhibited high stability on the material surface independent of whether viable virus was detected. These findings provide useful information for logistics practitioners and the general public to appropriately deal with transport items under different conditions to minimize the risk of epidemic transmission. IMPORTANCE This study shows the environmental stability of SARS-CoV-2 Variants Omicron BA.1 and BA.5 on surfaces of widely used transport packaging materials. The findings demonstrate that the environmental stability of the SARS-CoV-2 Omicron variants varies based on material type. The viability of SARS-CoV-2 on material surfaces depends heavily on temperature and viral titer. Low temperatures and high viral titers promote virus survival. Moreover, in contrast to virus viability, virus nucleic acid exhibits high stability on the surfaces of widely used materials, making the detection of virus nucleic acid unsuitable for evaluating the risk of epidemic transmission.

Keywords: Omicron variants; SARS-CoV-2; environmental stability; surface; transmission.

FIG 1

Virus nucleic acid copies of samples recovered from Omicron BA.5-inoculated nonwoven fabric at 4°C. A total of 400 μL of recovered sample was used for nucleic acid extraction, and the viral RNA copy numbers were measured via reverse transcription-PCR (RT-PCR) using primers and a probe targeting the SARS-CoV-2 N gene. Quantification was calculated according to the standard curve. The results are expressed as the mean ± SD. RH, relative humidity.

FIG 2

Virus nucleic acid copy numbers of samples with live virus detected (+) and not detected (−) from Omicron BA.5-inoculated nonwoven fabric at 4°C. (A) Scatter diagram of RNA copy numbers from samples inoculated with different virus titers. Samples detected with or without live virus are differentially displayed. (B) RNA copy numbers of samples with live virus detected (+) and not detected (−) from 100 TCID₅₀ BA.5-inoculated nonwoven fabric at 4°C. The results are expressed as the mean ± SD. The values were evaluated with Student's t test.