influenza assays detected both influenza virus A and B , and a test positive for influenza A or B was considered a single positive test . Each positive or negative test result represented a result obtained from a single sample , not a unique individual .
The predominant strains of SARS-CoV-2 circulating during different periods were determined from state , national ( Global Initiative on Sharing Avian Influenza Data [ GISAID ]), and local databases . The majority of samples obtained from WVU Medicine sites with known variant status were sequenced by the West Virginia University Rapid Development Laboratory ( WVURDL ). This laboratory was estab- lished as part of the state ’ s response to the COVID-19 pandemic .
Statistical analyses were performed to detect differences in SARS-CoV-2 and influenza test positivity rates throughout different phases of the pandemic . Test positivity rate is defined as positive tests divided by total tests performed . Correlations between SARS-CoV-2 and influenza test positivity were studied using the non-parametric Spearman ’ s correlation technique .
RESULTS
The baseline positivity rate of influenza during the pre-pandemic period of July 2018 to July 2019 was 7.2 % ( 2,182 / 30,008 ).
Overall , 602,109 tests for SARS-CoV-2 and 186,563 tests for influenza were performed between March 1 , 2020 , to June 17 , 2022 ( Table 1 ). There were approximately three times as many SARS-CoV-2 tests performed for every influenza test performed , reflecting a bias toward ordering more tests for COVID-19 . The test positivity rate was significantly higher for SARS-CoV-2 than influenza ( 13.7 % vs . 2.2 %, p < 0.0001 ). WV variant data from late 2020 to the end of the study is shown in Figure 1 .
The seasonal influenza season that preceded the COVID-19 pandemic began in December 2019 ( 2019 / 2020 season ), with
Weeks ( Predominant Variant )
TABLE 1 : Summary of test positivity for SARS-CoV-2 and influenza during different phases of the COVID-19 pandemic and correlation between number of positive tests for each virus .
# Tests Performed
Mar 2020-Sep 2020 ( Mixed Variants )
# Inpatient Tests Performed
# ED Tests Performed
ED = Emergency Department ; N . S . = Not Significant ; N . A . = Not Applicable
# Outpatient Tests Performed
# Positive Tests
Test Positivity Rate %
SARS-CoV-2 74,261 12,137 8,143 53,981 3,766 5.10 %
Influenza 10,922 1,793 7,298 1,831 729 6.70 % Nov 2020-Jan 2021 ( B . 1.2 ) SARS-CoV-2 71,661 11,761 11,715 48,185 11,709 16.3 Influenza 13,947 1,146 11,267 1,534 50 0.36 Mar 2021-Jun 2021 ( Epsilon / Alpha ) SARS-CoV-2 68,908 19,295 17,563 32,050 4,026 5.8 Influenza 17,495 1,741 14,301 1,453 42 0.24 Aug 2021-Oct 2021 ( Delta )
SARS-CoV-2 110,608 17,289 22,324 70,995 17,188 15.5
Influenza 18,644 1,878 12,240 4,526 2 0.01 Dec 2021-Mar 2022 ( Omicron BA . 1 ) SARS-CoV-2 145,284 28,695 24,875 91,714 32,961 22.7 Influenza 69,386 7,203 39,032 23,151 2,047 3 Apr 2022-June 2022 ( Omicron BA . 2 ) SARS-CoV-2 49,306 12,580 15,143 21,583 5,641 11.4 Influenza 34,432 3,222 12,673 18,537 1,064 3.1 Totals From March 2020 Through June 2022 SARS-CoV-2 602,109 118,031 115,718 368,360 82,751 13.7 Influenza 186,563 19,907 113,574 53,082 4,054 2.2
Correlation ( p-value )
-0.18 ( 0.006 )
N . S .
N . S .
N . S .
-0.23 ( 0.024 )
-0.61 (< 0.001 )
N . A .
West Virginia Medical Journal • June 2023 • 23