Test methods and references

SARS-CoV-2 (COVID-19) IgG + IgM panel:
IgM rapid test + SARS-CoV-2 (COVID-19) Roche total antibody test.
Price: 49€

SARS-CoV-2 (COVID-19) IgG test:
SARS-CoV-2 (COVID-19) Roche total antibody test.
Confirmation of a positive result by DiaSorin SARS-CoV-2 (COVID-19) IgG test. Price: 25€

INFO: COVID-19 serology testing

The detection of antibodies directed against SARS-CoV-2 has been available since the 4th of May 2020.

Serological tests allow for proper identification of people who mounted an immune response against the SARS-CoV-2 virus (regardless of whether they were symptomatic). Serology tests are blood-based tests and the determination of antibodies is performed in blood samples (serum).

Antibody detection tests: IgM and / or IgG production is only detectable on average within the second week after symptom onset in symptomatic patients.

We would like to point out, that at the current stage:

  • Serological tests are not used to diagnose an acute infection (see Ministry of Health Circular from the 30th March on prescription of COVID-19 diagnostic tests).
    Molecular testing technology by RT-PCR help identify the genome of the coronavirus SARS-CoV-2. It remains the only technology recommended for the biological diagnosis of COVID-19 to date.
  • The interest of serology will be to screen people who have had contact with the virus and who have developed an immune response.

But:

  • So far, serological tests will not allow to determine how contagious those persons are likely to be.
  • The kinetics of antibody production against the virus is not well defined yet, especially in asymptomatic people.
  • The time period of a possible immunity is also unclear.

These applications and recommendations will be regularly updated according to the rapidly evolving knowledge on COVID-19 and to the governmental recommendations.

Serology tests and PCR-based tests cannot supersede each other, but rather effectively complement each other in the current epidemic situation.

RT-qPCR testing is especially useful for early detection of the disease and it will help prevent drawing wrong conclusions from a negative serology, which may have been performed too early (that is, before the immune shift). Serological tests help document the emergence of adaptive immunity and reach retroactive diagnosis.

Prescription: A medical prescription and a blood sample (1 tube) are required for the serology tests.

CNS medical acts (nomenclature): There is no detailed information available in this respect. We will get back to you at the earliest opportunity once we have received more information.

COVID-19 detection by PCR using a nasopharyngeal or an oropharyngeal swab

PCR testing should be conducted to detect the presence of the virus in patients. It will only be carried out by a medical prescription using a nasopharyngeal or an oropharyngeal swab (when collection of a nasopharyngeal specimen is not possible).

The sample quality has a direct impact on the quality of the test results. The swab sample should be collected by a healthcare professional trained on sampling methods in use.

References:

  1. Pharyngeal swab figures in the list of specimens to be collected of the WHO Downloads/WHO-COVID-19-laboratory-2020.5-eng.pdf
  2. CDC: Allowance for oropharyngeal swabs as an acceptable specimen type if NP swabs are not available https://www.cdc.gov/coronavirus/2019-nCoV/lab/guidelines-clinical-specimens.html
  3. Robert-Koch-Institut: Oropharynx swab is included in the list of specimens eligible for PCR detection https://www.rki.de/DE/Content/InfAZ/N/Neuartiges_Coronavirus/Vorl_Testung_nCoV.html
  4. Posterior oropharyngeal saliva samples are a non-invasive specimen more acceptable to patients and health-care workers. https://www.thelancet.com/journals/laninf/article/PIIS1473-3099(20)30196-1/fulltext
  5. For proper sampling, the nasopharyngeal swab has to be rub-rolled while touching the mucosa. Patients report it as uncomfortable feeling - risk of hesitant sampling and false negative.
    Goyal 2017 showed that every fifth participant felt uncomfortable with the nasopharyngeal sampling. https://onlinelibrary.wiley.com/doi/10.1111/irv.12471
  6. Nasopharyngeal versus pharyngeal swab: The sensitivities were variable among the eight viruses tested; neither specimen was consistently more effective than the other. https://virologyj.biomedcentral.com/articles/10.1186/s12985-015-0408-z
  7. Germany and Switzerland: pharyngeal swabs are performed in drive in centers