Coronavirus disease 2019 (COVID-19) is an infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Common symptoms include fever, cough, and shortness of breath. The time from exposure to onset of symptoms is typically around five days but may range from two to fourteen days.
The standard method of diagnosis is by real-time reverse transcription polymerase chain reaction (rRT-PCR) from a nasopharyngeal swab. Chest CT imaging also be helpful for diagnosis in individuals where there is a high suspicion of infection based on symptoms and risk factors. Other serological tests such as ELISA and lateral flow tests are served as supplement for aiding purpose. Now, we will discuss the results analysis of serum antibody assay and RT-PCR.
Test by serum antibody assay (colloid gold)
| IgG | IgM | |
| + | - | |
| + | The patient maybe has been infected by SARS-CoV-2, and the patient is under the "active phase" | The patient maybe had been infected by SARS-CoV-2 before, but now the virus has been eliminated, so the IgG can be detected. However, the patient maybe infected again, so the result needs to be confirmed by the RT-PCR |
| - | The patient is under the "early phase", or some other illness causes the IgM false negative, so the result needs to be confirmed by the RT-PCR | The patient maybe hasn't been infected by SARS-CoV-2, the result needs to be confirmed by the RT-PCR |
Test by serum assay and RT-PCR
| IgG | RT-PCR Positive | RT-PCR Negative | IgM |
| + | The patient is under the "active phase", but people has produced the antibody to protect themselves in a way | The patient was infected by SARS-CoV-2 before, he is under the "recovery phase", the virus has been eliminated. However, the result of RT-PCR maybe false negative, so repetitive RT-PCR is necessary | + |
| - | The patient is under the "early phase", the viral load isn't high enough to be tested by the serum assay | The patient isn't infected by the virus, so no antibody is produced | - |
| + | The patient is under the "middle and late phase", people has produced the sufficient persistent antibody IgG. However, if the concentration of IgG is 4 times of "active phase", which means the patient is infected again | The patient maybe had been infected by SARS-CoV-2, but now the virus has been eliminated, people has developed the immunity | - |
| - | The patient is under the "early phase", the concentration of IgG is too low to be tested | The patient is under the "active phase", in addition, the result of RT-PCR maybe false negative, so repetitive RT-PCR is necessary | + |
Introduction of our products: COVID-19 IgG/IgM rapid test kit
You can find our COVID-19 IgG/IgM rapid test kit in link below.
