Coronaviruses are important human and animal pathogens. At the end of 2019, a new coronavirus was identified as the cause of a cluster of pneumonia cases in Wuhan, a city in China's Hubei province. It quickly spread, leading to an epidemic across China, followed by an increasing number of cases in other countries around the world. In February 2020, the World Health Organization designated the disease COVID-19, which stands for coronavirus disease 2019. The virus that causes COVID-19 is SARS-CoV-2.

The duration of protection during which a patient after infection and / or vaccination remains clinically protected and the evolution of their serology as well as their titre remains unknown

Inclusion criteria:

• Age> 75 years old
• Patient hospitalized or resident in the geriatrics center from July 1, 2020 to November 30, 2021 having presented with COVID or having benefited from a COVID vaccination.
• Subject not having expressed their opposition, after information, to the reuse of their data for the purposes of this research

Exclusion criteria:

• Subject having expressed opposition to participating in the study
• Impossibility of providing the subject with enlightened information (difficulties in understanding the subject, etc.)
• Subject under guardianship, curatorship or safeguard of justice

Adult patient hospitalized or resident in the geriatrics center from July 1, 2020 to November 30, 2021 having presented with COVID or having benefited from a COVID vaccination.