A SARS-CoV-2 outbreak in a plastics manufacturing plant

BMC Public Health

Table 1 Surface samples taken following a SARS-CoV-2 outbreak at a manufacturing workplace, March 2021, in England

RT-PCR results (From a total of 66 samples)			Level of RNA (based on Ct value)
Confirmed Positive	Suspected Positive	Negative	Moderate-High (Ct <32.0)	Low (Ct 32.0-34.9)	Very low-None (Ct ≥35.0^a)
8 (12.1%)	11 (16.7%)	47 (71.2%)	0 (0.0%)	0 (0.0%)	66 (%)
Positive sample information
Site area	Location in area	Mean Ct value^b		Estimated copies per cm^2c
Ops Office	Desk and Chair Arms	37.5		699
Assembly	Desk and Under Chair	37.1		935
Assembly	Stationery Cupboard	37.7^d		1075
Production	Tool Trolley	36.8		2757
Maintenance	2x Clamps + Cupboard	37.8		329
Tool Room	Cupboard	36.7		2641
Tool Room	Computer	37.3		1524
Tool Room	G Clamp Handle	37.7^d		2206
Production	Machinery	37.6^d		1155
WC	Dryer - Board Underneath	37.3^d		922
Canteen 2	Table and Chairs	37.3^d		997
Canteen 2	Leather Seat	37.4^d		1347
Maintenance Office	Cupboard - Handles and Inner Door	37.9^d		882
Warehouse	Aircon unit	36.7		918
Warehouse	Cleaning station - tool handles	37.5^d		103
Locker room	Locker	37.3^d		919
Locker room	Front of 140, 141	37.5^d		790
Locker room	Bench	37.9		418
Locker room	Bench	37.4^d		430

Abbreviations: RT-PCR Reverse transcription-polymerase chain reaction, Ct Cycle threshold, Ops Operations, WC Water Closet
^aIncludes 47 samples with no SARS-CoV-2 RNA detected
^bMean Ct value for the N gene
^cExtrapolation from copies per reaction to copies per sample collected based on the dilution factor, then divided by recorded sampling area
^dSample identified as suspected positive, defined as a sample with a single replicate testing positive for at least one target

ISSN: 1471-2458