PERFORMANCE OF RAPID ANTIBODY TEST AND RT-PCR AS FRONTLINE TEST FOR COVID-19 DIAGNOSIS IN PREGNANCY: AN EXPERIENCE IN INDONESIA

. Ensuring an accurate diagnosis is critical for limiting the spread of SARS-CoV-2 and for the clinical management of COVID-19, especially in pregnant women. For now real-time reverse transcription polymerase chain reaction (RT-qPCR) is the currently recommended laboratory method for the diagnosis of acute SARS-CoV-2 infection. More recently, several easy-to-perform rapid antigen detection tests have been developed and are recommended as first-line screening test in several countries. The purpose of this study was to evaluate the comparative performance of a rapid antibody test and RT-PCR for the detection of SARS-CoV-2 infection, as a front-line test for the diagnosis of COVID-19 in pregnancy. This research method is a descriptive study to describe comparation of sensitivity and specificity between rapid SARS-CoV-2 antibody test to the gold standard nasopharyngeal RT-PCR swab test. Of the 271 samples, only 257 were eligible and fourteen cases were excluded from the study due to a lack of rapid antibody test and RT-PCR results. The results of this study showed that the rapid SARS-CoV-2 antibody test sensitivity was 80.95%, and the specificity was 90.68%, the NPV (negative predictive value) and the PPV (positive prognosis value) were 98.17% and 43.59%, respectively. Based only on the results of IgM and IgG, IgM and IgG sensitivity were 33.33% (7/21) and 71.43% (15/21), respectively, and the specificity was 91.1% (215/236, 21 false positive) and 91.53% (216/236, 20 false positive), respectively. The use of rapid antibody tests during pregnancy is a screening tool and is not currently applicable for diagnostic tool. To minimize false positives and negatives results, the use of rapid antibody tests should be combined with the RT-PCR test results.


INTRODUCTION
The COVID-19 virus is spreading rapidly from person to person in China, and the World Health Organization (WHO) has reported an outbreak of COVID-19 is now spreading globally (Almaghaslah et al., 2020).Highly sensitive and specific tests are critical for the diagnosis and treatment of COVID-19 patients (Scohy et al., 2020) This was announced by the Centers for Disease Control and Prevention (CDC), pregnant women appear to be at the same risk as non-pregnant adults, with data on pregnancy status available for 91,412 (28.0%) women with laboratory-confirmed infection; of these, 8,207 (9.0%) were pregnant (Berghella, et al., 2020).The reliable laboratory testing is necessary because the number of suspected cases increases.RT-PCR testing of asymptomatic or mildly symptomatic individuals may be considered when evaluating people who have been in close contact with a confirmed case of COVID-19 (Scohy et al., 2020); WHO, 2020).

Real-time reverse transcription
polymerase chain reaction (RT-qPCR) is the currently recommended method for the diagnosis of acute SARS-CoV-2 infection.
However, several factors such as specialized equipment and skilled personnel limit the use of this method (Scohy, et al., 2020).
Higher viral load linked to better antigen detection rates and antibody formation in blood (Scohy, et al., 2020;WHO, 2020).Seroconversion may not occur 1-3 weeks after onset of the symptoms, so this test method may be of limited use in diagnosing acute infections.However, detection of anti-SARS-CoV-2 antibodies in serum can be used to determine the transmission chains, which may be useful for contact tracing investigation (Berghella, et al., 2020).
Currently, all government and private hospitals in Bali use rapid antibody tests as to screening all pregnant women who are going to have obstetric procedure.
However, many of the cases detected using as of serological tests based on antibodies could be very helpful (Kontou, Braliou, Dimou, Nikolopoulos, & Bagos, 2020).

Table 1 .
Distribution of study population Performance of Rapid Antibody Test and RT-PCR as Frontline Test for COVID-19 Diagnosis in Pregnancy: an Experience in Indonesia The Autobio Anti-SARS-CoV-2 Rapid Test is based on a one-step detection method.The cassette contains membranes pre-coated with two mouse anti-human monoclonal antibodies (anti-IgG and anti-IgM) on two separate assay lines.SARS-CoV-2 recombinant spike protein antigen reagents capable of specific binding to SARS-CoV-2 antibodies (IgM and/or IgG) were bound to colloidal gold and sprayed onto the conjugate pad.When the sample is applied to the test well, a complex of antibody and labeled antigen are formed and migrates to the top of the strip.Goldlabeled colorimetric reagents are used to form visible red/pink lines.

Table 3 .
Comparisons of IgM and IgG results for 21 cases with RT-PCR positive COVID-19 cases and 236 cases with discarded COVID-19.