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Volume 28, Number 3—March 2022
Dispatch

Relationship of SARS-CoV-2 Antigen and Reverse Transcription PCR Positivity for Viral Cultures

Dustin W. CurrieComments to Author , Melisa M. Shah, Phillip P. Salvatore, Laura Ford, Melissa J. Whaley, Jennifer Meece, Lynn Ivacic, Natalie J. Thornburg, Azaibi Tamin, Jennifer L. Harcourt, Jennifer Folster, Magdalena Medrzycki, Shilpi Jain, Phili Wong, Kimberly Goffard, Douglas Gieryn, Juliana Kahrs, Kimberly Langolf, Tara Zochert, Christopher H. Hsu, Hannah L. Kirking, Jacqueline E. Tate, and for the CDC COVID-19 Response Epidemiology Field Studies Team1
Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA (D.W. Currie, M.M. Shah, P.P. Salvatore, L. Ford, M.J. Whaley, N.J. Thornburg, A. Tamin, J.L. Harcourt, J. Folster, M. Medrzycki, S. Jain, P. Wong, C.H. Hsu, H.L. Kirking, J.E. Tate); Marshfield Clinic Research Institute, Marshfield, Wisconsin, USA (J. Meece, L. Ivacic); Winnebago County Health Department, Oshkosh, Wisconsin, USA (K. Goffard, D. Gieryn); University of Wisconsin‒Oshkosh, Oshkosh (J. Kahrs, K. Langolf, T. Zochert)

Main Article

Table 2

Symptoms and exposure history of persons testing positive for SARS-CoV-2, stratified by ability to culture virus and RT-PCR/antigen test concordance, Winnebago County, Wisconsin, USA, November-December 2020*

Characteristic Culture positive
 Culture negative
RT-PCR+/ antigen–, n = 9 RT-PCR+/ antigen+, n = 191 All, n = 200 RT-PCR+/ antigen–, n = 58 RT-PCR+/ antigen+, n = 76 All, n = 134†
Symptomatic
Current symptoms 7 (77.8) 165 (88.2) 172 (87.8) 43 (73.7) 67 (88.2) 109 (82.0)
No current symptoms 2 (22.2) 22 (11.8) 24 (12.2) 15 (26.3) 9 (11.8) 24 (18.0)
Unknown/missing
 0
 4
 4
1
1
Meets CSTE clinical criteria‡
Yes 7 (77.8) 142 (74.3) 149 (74.5) 36 (62.1) 60 (78.9) 96 (71.6)
No
 2 (22.2)
 49 (25.7)
 51 (25.5)
22 (37.9)
 16 (21.1)
 38 (28.4)
Days from symptom onset to specimen collection, median (IQR)
 2 (1–6 d)
 3 (1–4)
 3 (1–5)
3 (1–10)
 4 (2–7)
 4 (2–7)
Known exposure in previous 14 d
Yes 5 (55.6) 111 (58.7) 116 (58.6) 34 (59.7 39 (52.0) 73 (55.3)
No 1 (11.1) 42 (22.2) 43 (21.7) 19 (33.3) 22 (29.3) 41 (31.1)
Unknown 3 (33.3) 36 (19.1) 39 (19.7) 4 (7.0) 14 (18.7) 18 (13.6
Missing
 0
 2
 2
1
 1
 2
Days since last known exposure, median (IQR)
 2 (0.5–4)
 4 (0–6)
 4 (0–6)
2 (0–4 d)
 3 (0–7)
 2 (0–6)
N gene Ct value, median (IQR) 26.6 (25.6–31.0) 19.1 (17.1–21.3) 19.2 (17.2–21.7) 30.9 (29.3–33.4) 24.3 (21.1–27.7) 27.9 (23.8–30.9)

*Values are no. (%) except as indicated. CSTE, Council of State and Territorial Epidemiologists; Ct , cycle threshold; IQR, interquartile range; N, nucleocapsid; RT-PCR, reverse transcription PCR; SARS-CoV-2, severe acute respiratory syndrome coronavirus 2; +, positive; ‒, negative. †All specimen pairs included tested positive by RT-PCR; the 2 participants who had false-positive antigen test results, both of whom were culture negative, were excluded. ‡CSTE clinical criteria are met if the case-patient has either cough, shortness of breath, loss of taste, or loss of smell, or >2 of the following symptoms: fever, chills, myalgia, headache, or sore throat.

Main Article

1Members of CDC COVID-19 Response Epidemiology Field Studies Team who collected data are listed at the end of this article.

Page created: November 12, 2021
Page updated: February 21, 2022
Page reviewed: February 21, 2022
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