Context:

Therapeutic plasma exchange is an extracorporeal blood purification technique that removes pathogenic substances (including antibodies) from plasma. This technique also combines an immunomodulatory effect. The impact on the anti-SARS-CoV-2 titre and the humoral and cellular responses in the general population benefiting from therapeutic plasma exchanges is not known at this time.

The purpose of this study is to evaluate the evolution of anti-SARS-CoV-2 antibodies' titre over time in vaccinated adult patients treated with therapeutic plasma exchange.

Research question and associated variables:

Prospective non-drug interventional study on the possible variation of anti-SARS-CoV-2 antibody titre in adult patients regularly treated with therapeutic plasma exchange.

Study population: any adult patient vaccinated against SARS-CoV-2 (any type of vaccine) and regularly receiving therapeutic plasma exchange in the adult hematology department of the Cliniques universitaires Saint Luc in Brussels, Belgium.

Number of subjects expected to be enrolled: 10-15

Not provided

Inclusion Criteria:

• Adult patients vaccinated against SARS-CoV-2 (any type of vaccine) and regularly receiving therapeutic plasma exchange in the adult hematology department of the Cliniques universitaires Saint Luc.

Exclusion Criteria:

• Patients treated with therapeutic plasma exchange for an acute condition at the intensive care unit
• Patients unable to sign the ICF or unwilling to participate to the study