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Table of Contents
Year : 2022  |  Volume : 8  |  Issue : 2  |  Page : 116-120

Detection of COVID-19 using rapid point-of-care chromatographic immunoassay-based test

1 Department of Microbiology, Santosh Medical College and Hospital, Ghaziabad, Uttar Pradesh, India
2 Department of Microbiology, Government Institute of Medical Sciences, Greater Noida, Uttar Pradesh, India

Date of Submission24-Nov-2022
Date of Acceptance24-Nov-2022
Date of Web Publication11-Jan-2023

Correspondence Address:
Dakshina Bisht
No. 1, Santosh Nagar, Pratap Vihar, Ghaziabad - 201 009, Uttar Pradesh
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/sujhs.sujhs_39_22

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Introduction: Coronavirus disease 2019 (COVID-19) has so far affected over 41 million people globally. The limited supply of real-time reverse transcription-polymerase chain reaction (rRT-PCR) kits and reagents has made meeting the rising demand for incompetent. Therefore, numerous easy-to-use rapid antigen tests (RATs) based on lateral flow technology have been developed and are the need of the hour. This has a risen a crucial need for point-of-care devices for on-site detection. The objective of this study was to detect SARS-CoV-2 in suspected persons by rapid point-of-care (POC) chromatography immunoassay-based test.
Aim: The present study was conducted during the initial pandemic where all suspected cases were subjected to rapid POC chromatography immunoassay-based test and evaluated the outbreaks of COVID-19.
Materials and Methods: A cross-sectional study was conducted among 239 patients suspected of COVID-19. Nasal samples were collected for the rapid diagnostic test. The rapid chromatographic immunoassay test was performed immediately in all the patients.
Results: Of the 239 sample that were tested by Rapid antigen detection test, 89 (37.2%) were positive and 150 (62.7%) were found negative. Maximum number of patients that were positive from 60-74 years of which male were 23 (25.8%) and female were 13 (14.6%) and minimum number of cases were from above 75 years in which male were 5 (5.6%) and female 2 (2.2%).
Conclusion: The RAT showed an admirable specificity to rule in COVID-19 patients within the first 5 days of illness and had a reasonable sensitivity. Therefore, patients showing positive results need to immediately get treatment and those with negative tests should be reconfirmed by rRT-PCR as it is considered the gold standard for COVID-19 testing.

Keywords: Antigen test-coronavirus disease 2019, point-of-care testing, SARS-CoV-2

How to cite this article:
Singh S, Bisht D, Rawat A, Bansal J, Jain R. Detection of COVID-19 using rapid point-of-care chromatographic immunoassay-based test. Santosh Univ J Health Sci 2022;8:116-20

How to cite this URL:
Singh S, Bisht D, Rawat A, Bansal J, Jain R. Detection of COVID-19 using rapid point-of-care chromatographic immunoassay-based test. Santosh Univ J Health Sci [serial online] 2022 [cited 2023 May 30];8:116-20. Available from: http://www.sujhs.org/text.asp?2022/8/2/116/367574

  Introduction Top

The initial local outbreak of the “coronavirus disease 2019” (COVID-19) in Wuhan in December 2019 has become a worldwide pandemic.[1] One of the main reasons for the successful spread of the virus is the infectiousness before the onset of symptoms.[2] Transmission occurs mainly via droplet infection.[3]

An approach was used in India to augment testing for COVID-19 in underserved areas and health-care facilities. A combination of different tests and testing platforms has been used to augment capacity to 1.2 million tests per day, as of September 25, 2020. Indigenous portable Truelab (Molbio Diagnostics, India) workstations, previously used and recommended by the WHO for tuberculosis and also deployed for the detection of Nipah virus disease (unpublished) and leptospirosis (unpublished), are now being used for the detection of SARS-CoV-2. The Truelab workstation includes sample preparation, an RNA extraction system, a reverse transcription-polymerase chain reaction (RT-PCR) machine, and disposable kit components. This laboratory-in-a-suitcase can be used in remote areas and has network data transfer ability and an automated reporting system. Samples are collected in a viral lysis buffer with minimum biosafety and biosecurity requirements.[4]

Rapid tests have the potential to be used to inform triage of RT-PCR use, allowing earlier detection of those testing positive, but the evidence currently is not strong enough to determine how useful they are in clinical practice.[5]

For diagnosis, the SARS-CoV-2 genomic RNA is detected from upper and lower respiratory specimens.[6] The growing COVID-19 pandemic has led to a global crisis and crunch of laboratory-based molecular testing capacity and reagents.[7]

According to the data from the Centers for Disease Control and Prevention, the death rate of patients affected with COVID-19 is comparatively more in males in the age group between 75 and 84 years and in females with age 85 or above. The risk of death in people lesser than 45 years is minimum, while more deaths were reported due to COVID-19 in the age group of 65–74 years. Individuals infected with influenza and pneumonia showed the highest death rate in COVID-19-infected patients.[8]

These symptoms can be the same as those for other respiratory illnesses such as the common cold, influenza, body aches, headache, sore throat, runny nose, loss of taste or smell, nausea or vomiting, diarrhea, and seasonal allergies. The similarity of symptoms between COVID-19 and other respiratory illnesses makes it difficult to recognize a SARS-CoV-2 infection. Moreover, the incubation period of the virus varies greatly between people. Symptoms may appear 2–14 days after contact with the virus.[9]

The RT-PCR takes a minimum of 8–10 h from the collection of swabs to reporting of results, which can further increase in resource-limited and high-burden settings. In small towns and cities, molecular diagnostic laboratories are nonexistent and the reagents/viral transport medium and resources are difficult to procure. Therefore, the need of the hour is to rapidly detect and isolate positive cases to contain the disease spread, to quickly triage patients with severe acute respiratory illness in emergency departments, and to ramp up testing facilities.[10]

Antigen tests are relatively inexpensive, and most can be used at the point of care (POC). Most of the currently authorized tests return results in approximately 15–30 min. Antigen tests have been used for screening testing in high-risk congregate housing settings, such as nursing homes, in which repeat testing has quickly identified people with COVID-19, informing infection prevention and control measures, thus preventing transmission. In this case, and where rapid test turnaround time is critical, there is value in providing immediate results with antigen tests.[11]

It is a rapid chromatographic immunoassay for the qualitative detection of nucleocapsid antigens to SARS-CoV-2 present in human nasopharynx. It provides only an initial screening test result. The result of this test should not be the sole basis for the diagnosis; confirmatory testing is required.[12]

Thus, the present study was conducted during the initial pandemic where all suspected cases were subjected to rapid antigen detection test.

  Materials and Methods Top

This study was a cross-sectional study conducted in the Department of Microbiology, Santosh Medical College and Hospital, Ghaziabad, Uttar Pradesh, India. The total number of patients included in the study is 239 suspected of COVID-19.

Inclusion criteria

Patients suspected of COVID-19 and symptomatic health-care workers were included in the study.

Exclusion criteria

Children below 18 years and asymptomatic people were excluded from the study.

Nasal samples were collected for the rapid diagnostic test (RDT). The rapid chromatographic immunoassay test was performed immediately in all the patients as per the manufacturer's instructions (rapid chromatography).

Rapid antigen detection test

The Standard Q rapid antigen detection test (SD Biosensor, Inc., Gurugram) was evaluated in this study. The test was conducted on an NP swab specimen. The RDT kit consisted of a sterile swab, viral extraction tubes with buffer, tube nozzles, and a COVID-19 antigen test device.

Mouse monoclonal anti-SARS-CoV-2 antibody is coated on the test line region and mouse monoclonal anti-chicken IgY antibody is coated on the control line region on the surface of the nitrocellulose membrane. Mouse monoclonal anti-SARS-CoV-2 antibody conjugated with color 25 particles is used as a detector for SARS-CoV-2 antigen device.

Sample collection and extraction of antigen

Insert a sterile swab into the nostril of the patient and swab over the surface of the posterior nasopharynx. Withdraw the sterile swab from the nasal cavity. Samples were taken from both sides of the nasopharynx using a swab provided with the kit to maximize the viral load in the sample. The swab was inserted into the tube containing the extraction buffer provided with the kit and stirred into the buffer 5–6 times before squeezing and discarded. Remove the swab while squeezing the sides of the tube to extract the liquid from the swab and press the nozzle cap tightly onto the tube.

Allow three drops of sample to fall into the sample well, and it takes 15–30 min to out the results.


Nasopharyngeal samples were collected and processed using Standard Q rapid antigen detection test (SD Biosensor). After the test, bands were developed and interpreted in the following way:

The test device develops red bands at two positions: “C” control line and “T” test line – SARS-CoV-2 antigen. If red bands appeared at the “C” and “T” positions, the test was interpreted as positive. All red bands, including the faint ones, were taken as positive results. If the red band appeared at only the “C” position, it was interpreted as a negative result. The test was considered invalid if no red band appeared at the “C” position and was repeated.[12]

Statistical analysis

Data were entered in Microsoft Excel and descriptive statistics were used.

  Results Top

The majority of the 239 samples (147, or 62%) came from men, while the majority of the female samples (92, or 38%) came from women. The majority of the male samples—65, or 27.1%, and the female samples, 33, or 13.8%, came from people aged 60 to 74 (total 98), while the female samples, 6, or 2.5%, came from people over 75 (total 11) [Table 1].
Table 1: Distribution of cases based on gender and age groups (n=239)

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Among 239 cases of symptomatic participants, the most common symptom found was fever, in which 55 (23.01%) were male and 40 (17.7%) were female, followed by cough and sore throat, and the least common symptom was diarrhea, in which 8 (3.3%) were male and 4 (1.6%) were female.

All the 239 samples were tested for rapid antigen test (RAT) for the detection of COVID-19, where 89 (37.2%) samples tested positive and 150 (62.7%) samples were found to be negative. Of the 89 positive cases, maximum number of patients were reported in the age group of 60–74 years, in which 23 (25.8%) were male while 13 (14.6%) were female, and minimum number of cases were found in more than 75 years of age group, in which 5 (5.6%) were male and 2 (2.2%) were female.

Statistics of positive patients of the 89 (37.2%) samples that were tested positive were found in the month of November 32 (35.9%), August 2020 saw the highest number of instances with 21 (25.8%), followed by September 12 (13.4%), October 10 (11.2%), and July 9 (10.1%), while December 2020 saw the lowest number of cases with 6 (6.7%). The peak incidence was noted from the month of August to November 2020 [Graph 1], [Graph 2], [Graph 3].

  Discussion Top

In the pandemic context of COVID-19, diagnostic testing for SARS-CoV-2 is crucial to limit the spread of the virus as well as to effectively manage infected patients. Studies have shown that POC-based RATs have higher limits of detection.[13],[14],[15],[16] Moreover, the low-cost rapid antigen COVID-19 test with a good diagnostic performance represents a global health-care necessity.[17]

In the current study, 239 samples were collected and tested using a rapid antigen detection test to determine SARSCov2, followed by a comparative study of the age group, gender, and clinical symptoms of all positive cases.

In our study, maximum number of cases were from the age group of 60–74 years (40.9%), in which 65 (27.1%) were male and 33 (13.8%) were female. A similar study was done by Iftimie et al.[18] found that the greatest number of cases coming in the first wave from March to June 2020 among 80–89 years were male in hospitalized patients in Reus, Spain. Whereas, Han et al.[19] found that maximum number of cases were from 61 to 80 years of age group where 21 (39.6%) were male and 32 (60.3%) were female.

There were 92 (38%) female patients and 147 (62%) male patients among the 239 samples evaluated, suggesting that the low number of females who underwent testing may have been due to the lack of a correlation between gender and paramountcy which is also similar to study done by Gupta et al.[10] who observed that of the 330 total samples 231 (70%) were males and 99 (30%) were females which showed the ratio between males and females to be 0.42.

All 239 patients who sought treatment for symptoms including fever, cough, sore throat, exhaustion, headache, and diarrhoea were found to have fever 95 (39.7%) as their most prevalent symptom, followed by cough 47 (19.6%) and sore throat 38 (15.9%). A similar study shows that the challenge in detecting SARS-CoV-2 is difficult to identify and recognize the symptoms. In 2020, Wang et al. studied 138 novel coronavirus-infected pneumonia patients in a Wuhan hospital; the study found that 98.6% of patients experienced fever, 69.6% experienced fatigue, and 59.4% experienced a dry cough.[21]

In the present study of the total 239 cases, most of the clinical symptoms were from 60 to 74 years of age group where fever, cough, and sore throat were more common, which is similar to a study done by Liu et al.[22] All 221 COVID-19 patients were divided into two age groups, taking age group of 60 years as the threshold. One hundred and thirty-six cases (61.5%) were aged <60 years, and the other cases were aged >60 years. In total, 176 patients (79.6%) had fever. Other common symptoms included cough (48.0%), sputum (25.8%), sore throat (8.6%), and diarrhea (5.4%), among which only sore throat showed a significant difference between the two groups (11.8% vs. 3.5%; P = 0.034).

In the present study, we tested 239 samples, in which 89 (37.2%) samples tested positive and 150 (62.7%) samples were found to be negative. A study done by Ankesh Gupta et al. has found a smaller number of positive cases 64 (19.3%) out of 330 samples and 266 negative samples.[10] A similar method for testing done by Porte et al.[22] reported that evaluations of similar fluorescence immunochromatographic SARS-CoV-2 Rapid antigen test (Bioeasy Biotechnology Co., China) using universal transport medium with Nasopharyngeal and Oropharyngeal swabs in 127 suspected COVID-19 cases in which 82 (64.5%) samples were positive and 45 (35.4%) samples were negative.

The rapid POC chromatographic immunoassay-based test in the present study showed higher positive cases in the age group of 60–74 years. As a result, the SARS-CoV-2 Infection in older patients (60–74 years) remained more sensitive, which may result in serious problems. 52 of these guys (58.4%) showed a higher positivity rate than the 37 positive instances in the female group (41.5%). Similar to earlier research, Jian-Min Jin et al.[23] found that elderly patients (65 years old) were more likely to have a severe kind of COVID-19.

In the current study, we obtained the monthly statistics of positive cases from the 89 (37.2%) samples were tested positive in November, 32 (35.9%), and 23 (25.8%) patients in August 2020.

The advantages of RDT such as yielding rapid results, being at a reasonable price, and being safe due to viral inactivation and the fact that this does not require sophisticated laboratory setup or technical expertise make it an ideal test to be rolled out in high-prevalence community settings. Based on these findings, this test has been adopted in the diagnostic algorithms for Indian hospitals and an advisory has been issued by the ICMR in this regard.[24] However, because negative results cannot rule out SARS-CoV-2 infection, all negative tests should be covered by RT-PCR.

In Conclusion, With a respectable sensitivity, the fast antigen test demonstrated excellent specificity to exclude COVID-19 individuals within the first five days of sickness. As a result, patients with positive results should start receiving therapy right away, and those with negative results should have their results validated by rRT-PCR, which is the gold standard for COVID-19 testing.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

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