Secondary Subjects


  • Human subject means a living individual about whom an investigator conducting research: (1) obtains information or biospecimens through intervention or interaction with the individual and uses, studies, or analyzes the information or biospecimens; or (2) obtains, uses, studies, analyzes, or generates identifiable private information or identifiable biospecimens (as set forth in federal regulations at 45 CFR 46.102).
  • Primary research subject is an individual with whom the researcher interacts in order to collect data, or from whom the researcher directly collects identifiable information.
  • Secondary research subject is an individual about whom a researcher indirectly collects identifiable private information through interactions with a primary subject.
  • Private information includes information about behavior that occurs in a context in which an individual can reasonably expect that no observation or recording is taking place, and information which has been provided for specific purposes by an individual and which the individual can reasonably expect will not be made public (e.g., a medical or school record). In order to meet the above definition, private information must be individually identifiable (i.e., the identity of the subject is known or may readily be ascertained by the investigator or associated with the information) in order for the investigation to constitute research involving human subjects. In general, private information is considered to be individually identifiable when it can be linked to specific individuals by the investigator(s) either directly or indirectly through coding systems, or when characteristics of the information obtained are such that by their nature a reasonably knowledgeable person could ascertain the identities of individuals.

When does a study involve secondary subjects?

Study Example:

  • An investigator interviews a primary research subject and asks questions about the health of his/her family members. Those family members could become secondary research subjects if the investigator also obtains information that can uniquely identify them.

IRBs may differ in their interpretations of “identifiable private information.” To better understand the issues of interpretation, consider two examples:

  • An unemployed person provides household income information for a two-person household in which only one household member is employed.
  • A mother provides health information about the father of her child.

In the first example, the information is identifiable, but may not be considered private. In the second example, the information is private, but may not be considered identifiable if no identifying information was gathered about the father. However, if an IRB determines that these examples represent “identifiable private information,” then the Federal regulations require informed consent from the employed person or the father before such questions are asked.

Considerations for Protocols Involving Secondary Subjects in Research

Privacy and Confidentiality

Investigators must consider both primary and secondary subjects when developing data security plans in order to minimize a breach of confidentiality or an invasion of privacy. When doing so, investigators should take into account the sensitivity of the information collected, the potential risks to subjects if there were a breach of confidentiality, and additional protections for any vulnerable populations.
CPHS will assess investigators’ data security plans in order to ensure that the potential risk of breach of confidentiality and invasion of privacy are minimized for both primary and secondary subjects.

Informed Consent

It might be appropriate to obtain Informed Consent from secondary subjects (for example, a household survey where identifiable private information is obtained about a family member and the family member is present). If this is the case, there should be provisions for obtaining Informed Consent.

However, in most cases, it may be difficult to obtain informed consent from secondary subjects because of the indirect nature of their participation. If appropriate, investigators may ask CPHS to waive the requirement to obtain informed consent from secondary subjects. The Federal regulations (45 CFR 46.116(d)) state that IRBs may approve a waiver of consent if the IRB determines that:

  1. The research presents no risk of harm to the secondary subjects, considering probability and magnitude, greater than those ordinarily encountered in daily life or during the performance of routine examinations or tests;
  2. The research could not practicably be carried out without the requested waiver;
  3. If the research involves using identifiable private information or identifiable biospecimens, the research could not practicably be carried out without using such information or biospecimens in an identifiable format;
  4. The waiver will not adversely affect the rights and welfare of the secondary subjects; and
  5. Whenever appropriate, the secondary subjects will be provided with additional pertinent information after participation.

Where to address secondary subjects in eProtocol*

  1. Subject Population – Address the age range, gender, race, ethnicity, language, and fluency of secondary subjects, and include them in the total sample size. If secondary subjects include children/minors:
    1. Check Children/Minors in the Vulnerable Subject Checklist, and
    2. Include a rationale for their involvement in Part 5c (in a non-exempt application).
  2. Confidentiality – State what identifiable information is being obtained about secondary subjects, and account for both primary and secondary subjects in data security plans.
  3. Informed Consent or Child Assent & Parent Permission – If a non-exempt application, request a Waiver of Informed Consent, Child Assent, and/or Parent Permission or include the form for obtaining their Informed Consent, Child Assent, and/or Parent Permission.

*Because of potential consent issues when secondary subjects are involved in research, non-exempt review is generally required.

Questions about secondary subjects

Investigators whose research may involve secondary subjects are encouraged to contact OPHS to discuss how to best protect the rights and welfare of these subjects.

Related information