Infectivity of SARS-CoV-2 on Inanimate Surfaces: Don't Trust Ct Value

TY - JOUR

T1 - Infectivity of SARS-CoV-2 on Inanimate Surfaces: Don't Trust Ct Value

AU - Knobloch, Johannes K

AU - Pfefferle, Susanne

AU - Lütgehetmann, Marc

AU - Nörz, Dominik

AU - Klupp, Eva M

AU - Belmar Campos, Cristina E

AU - Kluge, Stefan

AU - Aepfelbacher, Martin

AU - Knobling, Birte

AU - Franke, Gefion

PY - 2022/12/19

Y1 - 2022/12/19

N2 - SARS-CoV-2 RNA is frequently identified in patient rooms and it was speculated that the viral load quantified by PCR might correlate with infectivity of surfaces. To evaluate Ct values for the prediction of infectivity, we investigated contaminated surfaces and Ct-value changes after disinfection. Viral RNA was detected on 37 of 143 investigated surfaces of an ICU. However, virus isolation failed for surfaces with a high viral RNA load. Also, SARS-CoV-2 could not be cultivated from surfaces artificially contaminated with patient specimens. In order to evaluate the significance of Ct values more precisely, we used surrogate enveloped bacteriophage Φ6. A strong reduction in Φ6 was achieved by three different disinfection methods. Despite a strong reduction in viability almost no change in the Ct values was observed for UV-C and alcoholic surface disinfectant. Disinfection using ozone resulted in a lack of Φ6 recovery as well as a detectable shift in Ct values indicating strong degradation of the viral RNA. The observed lack of significant effects on the detectable viral RNA after effective disinfection suggest that quantitative PCR is not suitable for predicting the infectivity of SARS-CoV-2 on inanimate surfaces. Ct values should therefore not be considered as markers for infectivity in this context.

AB - SARS-CoV-2 RNA is frequently identified in patient rooms and it was speculated that the viral load quantified by PCR might correlate with infectivity of surfaces. To evaluate Ct values for the prediction of infectivity, we investigated contaminated surfaces and Ct-value changes after disinfection. Viral RNA was detected on 37 of 143 investigated surfaces of an ICU. However, virus isolation failed for surfaces with a high viral RNA load. Also, SARS-CoV-2 could not be cultivated from surfaces artificially contaminated with patient specimens. In order to evaluate the significance of Ct values more precisely, we used surrogate enveloped bacteriophage Φ6. A strong reduction in Φ6 was achieved by three different disinfection methods. Despite a strong reduction in viability almost no change in the Ct values was observed for UV-C and alcoholic surface disinfectant. Disinfection using ozone resulted in a lack of Φ6 recovery as well as a detectable shift in Ct values indicating strong degradation of the viral RNA. The observed lack of significant effects on the detectable viral RNA after effective disinfection suggest that quantitative PCR is not suitable for predicting the infectivity of SARS-CoV-2 on inanimate surfaces. Ct values should therefore not be considered as markers for infectivity in this context.

KW - Humans

KW - SARS-CoV-2/genetics

KW - COVID-19

KW - RNA, Viral/genetics

KW - Trust

KW - Patients' Rooms

KW - Disinfection

U2 - 10.3390/ijerph192417074

DO - 10.3390/ijerph192417074

M3 - SCORING: Journal article

C2 - 36554950

VL - 19

JO - INT J ENV RES PUB HE

JF - INT J ENV RES PUB HE

SN - 1660-4601

IS - 24

M1 - 17074

ER -