COVID-19: how to use the Test

Published on 02/09/2020

SARS-CoV-2

Coronavirus Testing

When a communicable disease outbreak begins, the ideal response is for public health officials to begin testing for it early, in order to quickly identify the cases, begin treatment for those people and immediately isolate them to prevent spread.
That’s why an early disease diagnosis is fundamental: nowadays, the positivity of a subject to SARS-CoV-2 virus is confirmed by a nose-pharyngeal swab, subsequently analyzed with a molecular biology technique called PCR - Polymerase Chain Reaction. This technique involves the duplication of RNA in the laboratory, allowing exponential growth of the filament in just over an hour. In this way it is possible to isolate and study any trait of RNA from a biological sample.

PCR methodology, as part of the official protocol indicated by the WHO, is the main reference system for in vitro diagnostic devices aimed at identifying the COVID-19 pathology.

Antibody/Serology tests are diagnostic methods that are used to identify antibodies and antigens in a patient's sample (blood/serum/plasma). They normally provide the result in 10 minutes and can be done anywhere.

Principle of the Test

The Test is a qualitative membrane based lateral flow immunochromatographic assay for the detection of IgG and IgM antibodies against SARS-CoV-2 in whole blood, serum or plasma specimen. A diluent buffer is used to dilute the sample and favor sample flow along the test strip.

COVID-19 IgG/IgM Rapid Test is dedicated to healthcare professionals with the aim to support them in the COVID-19 emergency management, receiving quick answers about the health status of their patients:
- high Sensitivity and Specificity standards, when compared to a PCR Methodology
- safe and accurate results in just 10 minutes
- easy to use and to read.

Are you interested in buying our COVID-19 IgG/IgM Rapid Test kit? Please write to info@primahometest.com for further information.

Why using a serological test for COVID-19?

The use of a COVID-19 serological device is important because it allows to identify people potentially affected by SARS-CoV-2 and then take precautionary isolation measures in order to reduce further spread of the virus.
For this virus the incubation period is between 1 and 14 days, with a prevalence of 3 to 7 days, after which the first symptoms start to appear.

Figure 1

Sethuraman et al., show the trend over time of the detection of diagnostic tests for SARS-CoV-2. The detection increases after the onset of the first symptoms reaching a peak detection for nasopharyngeal swab in the first week after the onset of symptoms and then decreases steadily. Contrary to this, IgM and IgG antibodies to SARS-CoV-2 appear in the serum or plasma of infected individuals from a few days up to 2 weeks after these symptoms and, while IgM levels decrease after the end of the infection, IgG levels remain high and therefore detectable.

For this reason, these tests are useful for: (1) assist in the diagnosis of late symptomatic cases, as a support for molecular testing (nasopharyngeal swabs followed by PCR tests); (2) screen asymptomatic individuals who may have recently been exposed to the virus; (3) assist in seroprevalence investigations to define population exposure levels.

How does the Test work?

View the video Tutorial and follow the procedure.

A) Collect the blood sample:
1. Whole blood (fingerstick and venous sampling): fill the blood collecting pipette and transfer 20μL of whole blood sample into the sample well of the test cassette. As an alternative to the blood collecting pipette, 20μL of sample from venous sampling can be dispensed with a laboratory micropipette.
2. Serum and plasma: Transfer 10μL of sample to the sample well with a laboratory micropipette.

B) Apply two drops of diluent to the sample well, approximately 80μL, then wait for 10 minutes and then read the results. The results are valid for up to 20 minutes after adding the diluent. Beyond 20 minutes the results should not be considered.

Results interpretation

Positive IgG Results: Two coloured lines appear at the C (Control) and IgG signs, none at the IgM one. Contact the COVID-19 emergency reference number in your country and follow the instructions.

Positive IgM Results: Two coloured lines appear at the C (Control) and IgM signs, none at the IgG sign. Contact the COVID-19 emergency reference number in your country and follow the instructions.

Positive IgG/IgM Results: Three coloured lines appear at the C (Control), IgG and IgM signs. Contact the COVID-19 emergency reference number in your country and follow the instructions.

Negative Results: A coloured line appears at the C (Control) sign and none at the IgG and IgM ones.

The COVID-19 IgG/IgM Rapid Test will only indicate the presence of IgG and IgM antibodies to SARS-CoV-2 in the specimen and should not be used as the sole criteria for the diagnosis of SARS-CoV-2 infections. The results obtained with this test should be considered with other clinical findings from other laboratory tests and evaluations.