DIAGNOSIS FOR COVID-19 INFECTION (CORONAVIRUS)

The tests available to detect SARS-CoV-2 infection are as follows:
• molecular test (or PCR): performed on a rhino-pharyngeal swab, it shows the presence of genetic material (RNA) of the virus.
• antigen test: performed on a rhino-pharyngeal swab, it highlights the presence of virus components
• serological test: performed by venous sampling and capillary blood, it shows the presence of antibodies against the virus.

MOLECULAR SWAB

It is performed on a sample taken with a nasal / oro-pharyngeal swab which is analyzed through molecular methods of real-time RT-PCR (Reverse Transcription-Polymerase Chain Reaction) for the amplification of the viral genes most expressed during the infection. It is currently the most reliable test for diagnosing coronavirus infection. The result is provided on average within 48 hours of carrying out the same.

ANTIGENIC SWAB

This type of test is based on the search, in respiratory samples, for viral proteins, called antigens. As for molecular tests, it is performed on a sample taken with a swab at the nasal / oral-pharyngeal level. Response times are immediate, sensitivity and specificity appear to be lower than those of the molecular test. This involves the possibility of false-negative results in the presence of low viral load, as well as the need to confirm positive results with a molecular swab.

SEROLOGICAL TESTS

They are divided into traditional (quantitative) or rapid (qualitative) serological tests. Both show the presence of antibodies against the virus by detecting exposure to the virus (IgG) and the presence of an infection in progress (IgM). In the current state of scientific research, serological tests cannot replace the molecular test based on the identification of viral RNA. The positive result can be considered synonymous with an infection but needs to be confirmed by means of a molecular swab.