And if the fact of having contracted a minor form of the COVID-19 gave a protective immunity deal with the disease for several weeks? This is what the results of a survey by the Strasbourg CHU and the Institut Pasteur suggest.
A study to assess protective immunity after a mild form of COVID-19
Until now, scientists have known that people with severe forms of COVID-19 develop antibodies within 15 days of the onset of symptoms. But when it comes to people with minor forms of SARS-CoV-2 infection, the immunological response was still poorly understood.
In this context, teams from the Strasbourg University Hospital and the Pasteur Institute conducted a survey of 160 volunteer hospital staff members from the two Strasbourg University Hospital sites and infected with SARS-CoV-2. All had in common:
- To have been diagnosed positive by the PCR test.
- To have developed minor forms illness that did not require hospitalization.
The teams of scientists therefore sought to detect the presence of anti SARS-CoV-2 antibodies as well as the level of their neutralizing activity by means of various tests.
Protective immunity for several weeks
It will have taken several months of research and thousands of tests to finally obtain the certainty that a protective immunity COVID-19 does exist, even for patients who have developed minor form of the disease.
Scientists were able to observe the following results for the group of patients studied:
- Antibody detection in 95.6% of samples using the rapid immunodiagnostic test
- Antibody detection in 99.4% of samples using the S-Flow test
- Neutralizing antibodies (NAbs) detected in 79%, 92% and 98% of the samples taken, respectively between 13-20, 21-27 and 28-41 days after the onset of symptoms.
To know ! The S-Flow Test is a very sensitive and specific test that detects the SARS-Cov-2 protein S on the surface of the cell. This test is suitable for epidemiological research activities because it requires special reading equipment (flow cytometer), less common than the plate reader in analysis laboratories.
The results show that antibodies to SARS-CoV-2 are present in almost all of the hospital staff of the study. In addition, almost all caregivers (98%) developed neutralizing, i.e. protective, antibodies on the 28th day, which suggests that even for light forms of the disease, patients develop antibodies that could give them a immunity for several weeks following infection: “Our study shows that antibody levels are, in most cases, compatible with protection against re-infection with SARS-CoV-2, at least up to 40 days after the onset of signs. “, explain the researchers.
Next step for scientists? Assess the persistence of the immune response and its protective capacity in the long term in this nursing staff.
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Déborah L., Doctor of Pharmacy
– Coronavirus: immunity to the disease for at least 40 days. FRANCE TV INFO. Accessed May 27, 2020.
– Development and evaluation of four serological tests for anti SARS-CoV-2 antibodies and two neutralizing antibody tests. PASTOR INSTITUTE. Accessed May 27, 2020.-
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