A comparative study on persistence and viability of SARS-CoV-2 wild-type and omicron variant on artificially contaminated surfaces: the role of fomites

Indirect transmission of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) has been investigated but it is still not completely understood. The present study aimed to compare the persistence and viability of the lineage B.1 and omicron BA.1 subvariant in five daily use materials to evaluate the role of fomites as possible source of infection. Artificial contamination in a first set of experimental assay on ethylene vinyl acetate (EVA), cardboard, polystyrene, aluminium and plastic were carried out. Further experiments using omicron variant on five different surfaces (glass, plexiglass, cotton, polyester and tetrapak) were also conducted. The persistence, viability on Vero E6 cell cultures and the residual infectivity of the two lineages were evaluated over 5 days post contamination (p.c.). Results showed different stability between the tested matrices. Except for cotton and polyester, where the RNA was not detectable in 24 and 48h p.c., respectively, and the virus was not viable as soon as 30 min, in the other tested surfaces both lineages RNA was detectable until 120h p.c. A rapid decay of the viral load was revealed on cardboard, more evidently for the omicron variant. Furthermore, longer stability of BA.1 was demonstrated, but showing a less severe subtotal CPE on cell monolayers than the wild-type on all the tested materials. EVA was the material that better sustained virus stability, as the virus was able to develope CPE on the cells up to 72h p.c. In conclusion, it is conceivable to speculate about the potential spread of SARS-CoV-2, albeit it is difficult to establish the real capacity to infect people through indirect contact but such these information are of fundamental importance to help to adopt the appropriate measures to mitigate the spread of SARS-CoV-2 and its variants.