COVID-19 is a pathology linked to the SARS-CoV-2 virus, a new virus of the coronaviridae family that emerged in China in December 2019 before rapidly becoming a pandemic according to the WHO on March 11, 2020. The epidemic affected France from February 2020. On February 24, a patient hospitalized at Percy hospital was the cause of a major nosocomial epidemic, potentially responsible for more than 250 symptomatic people in the hospital as of April 6. The outbreak was identified by Percy hospital management on March 16, and barrier measures were immediately put in place. From March 20, a mixed investigation unit set up a chain of nasopharyngeal swabs for Percy hospital staff.

A COVID-19 case reporting unit was set up at Percy hospital in response to the identification of the outbreak within the hospital. This unit carried out rapid identification and regular follow-up until the return to work of the staff. Thus all symptomatic patients are identified and the COVID-19 case census cell will follow all Percy hospital staff, including volunteers recruited to deal with the epidemic, throughout the duration of the epidemic. This population, captive by nature, will be one of the few described in the world during this epidemic.

Current data on short-, medium- and long-term immunity induced by COVID-19 infection are fragmentary, as is the existence of a large asymptomatic population, making it difficult to cut the chains of transmission in the absence of an effective diagnostic tool.

Another important issue is the quality of immunity induced by the infection, as it conditions the future of the pandemic, which could become endemic and recurrent if immunity were not sterilizing. As yet unpublished data in primates show that in the primate model re-infection is not possible in the short term, while patients cured from the Wuhan epidemic seem to be detected again positive for virus shedding.

The objective of this study is to characterize the immunity (systemic and local) induced by SARS-Cov-2 infection among Percy hospital staff who are at high risk of contamination even in a period of confinement.

Inclusion Criteria:

• 18 years of age or older;
• Military or civilian or contactual volunteer on duty at Percy hospital during the COVID-19 pandemic.

Exclusion Criteria:

• Individuals who have displayed a severe form of early-onset COVID-19 who required intensive care management or hospitalization;

• Presence of factors modulating immunity with congenital or acquired immunosuppression:

  • Medication: cancer chemotherapy, immunosuppressive drugs, biotherapy, corticosteroids
  • Uncontrolled HIV infection or CD4 <200/mm3 infection
  • History of solid organ or hematopoietic stem cell transplants

Percy hospital staff having (symptomatic individuals group) or not (asymptomatic individuals group) presented COVID-19 infection symptoms.