Yes, the research activity that you describe is deemed to be issued a Certificate of Confidentiality (CoC), i.e., your research is covered by a CoC. All NIH-funded research activities in which the investigator collects or uses “covered information” is deemed to be issued a Certificate of Confidentiality.
Covered information includes the names or any information, documents, or biospecimens containing identifiable, sensitive information related to a research participant. In addition, if there is at least a very small risk that the information, documents, or biospecimens can be combined with other available data sources to determine the identity of an individual, then the NIH-funded research activity is also protected by a Certificate. Note that the focus of identifiable, sensitive information is primarily on the identifiability of information.
NIH does not issue a physical certificate or otherwise inform the investigator that the research activity is covered by a CoC. Instead, it is the responsibility of the investigator and the recipient institution to determine if the research they are conducting is subject to the NIH CoC Policy.
Investigators and recipient institutions who are collecting or using covered information cannot decline the CoC protections, as the CoC is issued as a term and condition of the NIH award.