Italian to English Medical Medical: Pharmaceuticals Notification letter of a merger between 2 healthcare facilities

Dear colleagues,

I am translating a letter that concerns the merger of 2 healthcare facilities. At the end it states:

CAdES 1 di 1 del 27/06/2017 14:16:36
Soggetto: 'Forename + surname'
S.N. Certificato: 2F0C 55
Validità certificato dal 13/12/2016 12:51:28 al 01/01/2018 02:00:00
Rilasciato da 'XYZ'

Does anyone know what S.N. refers to in S.N. Certificato: 2F0C 55?

Thanks in advance,

Salma