Received: 8 November 2017
Accepted: 21 February 2018
First Online: 27 February 2018
Ethics approval and consent to participate
: All participants gave informed written consent prior blood donating. The study was approved by Ethics Committee of the Pomeranian Medical University in Szczecin, Poland (decision No. BN-001/174/05.
: Not applicable.
: The authors declare that they have no competing interests.
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