USE OF SARS-COV-2 ANTIGEN RAPID DIAGNOSTIC TESTS FOR COVID- 19 SELF-TESTING
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Use of SARS-CoV-2 antigen rapid diagnostic tests for COVID- 19 self-testing INTERIM GUIDANCE 9 March 2022 Web Annex B. COVID-19 self-testing using antigen rapid diagnostic tests: Feasibility evaluation among health-care workers and general population in Malawi and Zimbabwe Euphemia Sibanda, Augustine Talumba Choko, Connie Watadzaushe, Madalo Mukoka, Moses Kumwenda, Florence Abok, Elizabeth L. Corbett, Elena Ivanova
© World Health Organization 2022. Some rights reserved. This work is available under the CC BY-NC-SA 3.0 IGO licence. WHO reference number: WHO/2019-nCoV/Ag-RDTs/Self_testing/Web_annex_B/2022.1 The named authors alone are responsible for the views expressed in this publication. This publication forms part of the WHO interim guidance: Use of SARS-CoV-2 antigen rapid diagnostic tests for COVID-19 self-testing: Interim guidance, 9 March 2022. It is being made publicly available for transparency purposes and information, in accordance with the WHO handbook for guideline development, 2nd edition (2014).
COVID-19 self-testing using antigen rapid diagnostic tests: Feasibility evaluation
among health-care workers and general population in Malawi and Zimbabwe
Euphemia Sibanda1, Augustine Talumba Choko2, Connie Watadzaushe1, Madalo Mukoka3, Moses Kumwenda2, 3,
Florence Abok4, Elizabeth L. Corbett5, Elena Ivanova4
1. CeSHHAR, Harare, Zimbabwe
2. Malawi Liverpool Wellcome Trust Clinical Research Programme, Blantyre, Malawi
3. Helse-Nord Tuberculosis Initiative, Kamuzu University of Health Sciences, Blantyre, Malawi
4. FIND, Geneva, Switzerland
5. London School of Hygiene & Tropical Medicine, London, UK
Background
COVID-19 testing services are critical for enabling identification of cases to prevent transmission.
Self-testing has the potential to increase diagnostic capacity for COVID-19 and to expand access to
hard-to-reach areas in low-and-middle-income countries. We investigated the feasibility and
acceptability of COVID-19 self-testing (C19ST) using SARS-CoV-2 Ag-RDTs in Malawi and
Zimbabwe.
Methods
Between July 2021 and February 2022, we conducted a mixed methods feasibility study examining
self-testing using STANDARD Q COVID-19 Ag Home Test (SD Biosensor) and Panbio COVID-
19 Ag Self-Test Device (Abbott Rapid Diagnostics) among health-care workers and the general
population across urban and rural settings. For each test kit, we conducted cognitive interviews to
optimize the instructions for use. Among the general population, we then conducted an
observational study where study staff demonstrated how to self-test, then gave each participant a
test kit with written self-test instructions and observed the participant as they self-tested. A checklist
was completed to document whether each step on the instructions was performed correctly. Study
staff also collected an anterior nasal sample that was tested for comparison purposes using an
antigen RDT of the same brand. Participants were shown contrived test kits to assess the ability to
interpret negative, positive and invalid results. Each participant was shown one negative result, a
positive result, a weak positive result and two types of invalid results (no control and test lines
present, and only test line present). The primary outcome was the proportion of participants who
attained the usability threshold defined as the ability to correctly conduct all 12 pre-defined critical
steps. The secondary outcome was percent agreement of self-test results with professional results.
Logistic regression was used to investigate factors associated with attaining the usability threshold.
Views and preferences were explored using in-depth interviews among people who had self-tested.
-1-Results Cognitive interviews found that there were no major suggestions for change of instructions for use. Lessons learned included the fact that it would be useful to make introductory text stand out (because most participants did not read it). Examples of other useful refinements included expanding some descriptions, placing additional labels on images and selecting words/phrases/illustrations that are well understood locally. A total of 1,204 participants were enrolled for the self-testing observational study. Mean ages were and 30.7 and 33.7 years in Malawi and Zimbabwe, respectively. In Malawi, the usability threshold was attained by 276/335 participants (82.4%: 95% CI: 77.9; 86.3) and 300/332 participants (90.4%: 95% CI: 86.7; 93.3) for Standard Q and Panbio, respectively (Table 1). In Zimbabwe the corresponding results were 136/208 (65.4%: 95% CI: 58.5; 71.8) and 233/330 (70.6%: 95% CI: 65.4; 75.5) for Standard Q and Panbio, respectively. Agreement between self-test results and professional test results was 332/333 (99.7%, 95% CI: 98.3-100%) and 330/330 (100%, 95% CI: 99.8-100%) for Standard Q and Panbio, respectively in Malawi (Table 2). In Zimbabwe, agreement was 205/207 (99.0%, 95% CI: 96.6-99.9%) and 321/328 (97.9%, 95% CI: 95.7-99.1). Errors on critical steps were more frequent in Zimbabwe than in Malawi (Tables 3-4). Participants in Zimbabwe were 70% less likely to attain the usability threshold compared to those in Malawi, (odds ratio (OR) = 0.29 95%CI: 0.20-0.41, p
Table 2: Agreement of self-test result with professional result (secondary outcome)
Country Percent agreement between self-testing and professional testing
Standard Q Panbio
Malawi 332/333 (99.7% 95% CI: 98.3-100%) 330/330 (100% 95% CI: 99.8-100%)
Zimbabwe 205/207 (99.0% 95% CI: 96.6-99.9%) 321/328 (97.9% 95% CI: 95.7-99.1)
Table 3: Self-tester performance across 12 critical steps, Panbio COVID-19 Ag Rapid Test
Device
Malawi (N = 331) Zimbabwe (N = 330)
Critical steps assessed Yes No Yes No
Did participant place tube on the kit box tray holder 329 (99.4) 2 (0.6) 329 (99.7) 1 (0.3)
correctly?
Did participant insert swab into the left nostril to the 332 (100 0 (0.0) 307 (93.0) 23 (7.0)
correct depth?
Did participant rotate the swab 5 times in the left 327 (98.5) 5 (1.5) 320 (97.0) 10 (3.0)
nostril?
Did participant insert the swab into the right nostril to 329 (99.4) 2 (0.6) 307 (93.0) 23 (7.0)
the correct depth?
Did the participant rotate the swab 5 times in the 330 (99.4) 2 (0.6) 322 (97.6) 8 (2.4)
right nostril?
Did the participant insert the swab into the solution 328 (99.4) 2 (0.6) 327 (99.1) 3 (0.9)
tube correctly?
Did the participant swirl in the fluid 5 times while 323 (97.6) 8 (2.4) 297 (90.0) 33 (10.0)
pushing against the wall of the Tube
Did the participant remove the swab slowly while 316 (95.5) 15 (4.5) 278 (84.2) 52 (15.8)
squeezing the sides of the tube to extract the liquid
from the swab?
Did the participant press the nozzle cap tightly onto 330 (99.7) 1 (0.3) 326 (98.8) 4 (1.2)
the tube?
Did the participant squeeze 5 drops of liquid from the 330 (99.7) 1 (0.3) 313 (94.9) 17 (5.1)
Tube into the well on the Test Device?
Did the participant read the test result in 15 minutes? 325 (97.9) 7 (2.1) 315 (95.5) 15 (4.5)
Did the participant interpret the test result correctly? 329 (99.7) 1 (0.3) 323 (97.9) 7 (2.1)
-3-Table 4: Self-tester performance across 12 critical steps – STANDARD Q COVID-19 Ag Test
Device
Malawi (N = 331) Zimbabwe (N = 208)
Critical steps assessed Yes No Yes No
Did participant place the solution tube on a flat 327 (97.6) 8 (2.4) 198 (95.2) 10 (4.8)
surface?
Did participant insert the swab into the left nostril 327 (97.6) 8 (2.4) 190 (91.4) 18 (8.7)
to the correct depth?
Did the participant rotate the swab 10 times in the 325 (97.0) 10 (3.0) 193 (92.8) 15 (7.2)
left nostril?
Did participant insert the swab into the right nostril 327 (98.5) 5 (1.5) 189 (90.9) 19 (9.1)
to the correct depth?
Did participant rotate the swab 10 times in the right 324 (97.0) 10 (3.0) 194 (93.3) 14 (6.7)
nostril?
Did participant insert the swab into the solution 331 (98.8) 4 (1.2) 207 (99.5) 1 (0.5)
tube correctly?
Did participant stir the swab more than 10 times 325 (97.3) 9 (2.7) 183 (88.0) 25 (12.0)
while squeezing the sides of the solution tube?
Did the participant remove the swab slowly while 310 (92.5) 25 (7.5) 186 (89.4) 22 (10.6)
squeezing the sides of the tube to extract the liquid
from the swab?
Did participant press the nozzle cap tightly onto the 326 (97.9) 7 (2.1) 203 (97.6) 5 (2.4)
tube?
Did participant apply 4 drops of extracted sample to 319 (95.5) 15 (4.5) 195 (93.8) 13 (6.2)
the sample well of the test device?
Did participant read the test result in 15 minutes? 333 (99.7) 1 (0.3) 203 (97.6) 5 (2.4)
Did participant interpret the test result correctly? 328 (98.5) 2 (1.5) 208 (100) 0 (0.0)
Table 5: Ability of self-testers to correctly interpret results using contrived test kits
Country Product Individuals correctly interpreting results
Positive test result Negative result (%) Invalid result (%)
(%)
Malawi Standard Q 329 (98.5) 332 (99.4) 324 (96.7)
(N = 331)
Panbio 325 (97.9) 327 (99.1) 317 (96.1)
(N = 331)
Zimbabwe Standard Q 202 (97.1) 206 (99.0) 203 (97.6)
(N = 208)
Panbio 315 (95.5) 312 (94.5) 284 (86.1)
(N = 330)
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