Table 1.

CFIR Domains & Constructs with Accompanying and Illustrative Quotes

Domain	Construct	Exemplar Quotes
1. Intervention Characteristics	1. Complexity	I think it is a very easy procedure. It could be done by anybody. It could be done by the person themselves. It could be done by a peer. It could be done by a volunteer. So, there is very little barrier on who can do this, and how they can do this and the amount of training that they have to go through. It’s very convenient in that regard. (Site Coordinator)
	2. Adaptability	I think you could have even achieved both things. The researchers fundamentally wanted their dried blood spot, while we have a finger pricked I don’t think it would have been difficult to do a Point-of-Care as well… I think that might have made people a little bit happier on the spot. (Volunteer)
	3. Relative Advantage	A. I think it was for the most part it was pretty low barrier and like not as intimidating. Even people who, just anecdotally would come up and, I was helping with recruitment so just hearing people say ‘I’m kind of afraid of needles but I’m going to do it’. Because we could go through and say, it’s not a full vial of blood from your arm, it’s a little finger prick. (Site Coordinator) B. I think it was honestly very beneficial in having community members volunteer and be trained to be able to do the dried blood spot because then it made their friends come, and friends of their friends and people that we might not have ever seen if we had the health professionals leading and doing that work. I think the fact that it felt more community-led and -owned was also something that encouraged a lot of folks to come and get their dried blood spot taken. (Site Coordinator)
	4. Cost	I thought that it was really good because if you’re going to have to pay healthcare professionals it’s going to cost you a fortune and there goes all your funding out the window, where it’s something that someone like me [a non-healthcare professional] can do so long as I have training. To me it’s a good, cost effective way to get it done. (Volunteer)
2. Process	1. Engaging	A. I think that the biggest motivation was the overall goal of the study… to help address blood donation. That was probably the biggest, the absolute biggest impetus for me. (Interviewee 14, Site Coordinator) B. Even before I worked for CBRC, I participated in the online Sex Now survey over the last couple of iterations because as a gay man I know that there’s not enough data about us out there and if we don’t participate, there never will be. (CBRC Staff)
	2. Executing	A. The day of implementation at the Pride Festival was an incredibly long, tiring and stressful day. I think I worked about 14 h straight…. I was pleasantly surprised with how well things went. We had very few issues with the actual collection process and recruitment process. (Site Coordinator) B. [E]very type of test you add, adds another level of complexity but one of the things that made it a little bit more challenging was when DBS results… were indeterminate for whatever reason. Like if not enough blood had been collected, or if there was a technical issue with the dried blood spot card, and sometimes the HIV result was sufficient but the Hep C wasn’t, and sometimes the Hep C was and the HIV wasn’t, sometimes they both weren’t sufficient, so for each little complication it just creates another branch of a complicated tree of how results are given. (CBRC Staff) C. [W]hen I was standing outside the tent and I was speaking to a few people, a few people actually declined to participate because I knew that they were [HIV] positive and I was trying to still encourage them to participate because there’s a whole point was that they were aware of that, but I think there was kind of that concern of, well you don’t want me because I’m going to kind of like taint the sample. (Volunteer)
3. Characteristics of Individuals	1. Knowledge and Beliefs about the Intervention	A. Increase in testing opportunities for folks, number one; Low barrier testing, number two; and then like data collection for direct policy change, number three. (Site Coordinator) B. I would be reassuring participants, if you’re testing for your own sake, we’re happy to have you in the survey and we hope you participate but don’t be using this for your testing services. I would tell them to give us their DBS and then go to the [clinic], so you can get your own result right away. I wouldn’t want anyone – especially if they’re concerned or unsure of their status waiting several months for that result. That would certainly not be ideal. (Site Coordinator)
4. Inner Setting	1. Available Resources	A. I thought a little bit with training there were some sites that we went out and trained them once and then they went off and did training later… it was kind of like a game of telephone. Some, it was nothing detrimental and nothing catastrophic that we weren’t able to correct as, as we went through additional training or through collection. Umm, but protocol fidelity becomes a challenge if there’s not someone there to monitor it. (CBRC Staff) B. [T]he individual that [partner organizations] would task with Sex Now often expressed feeling overwhelmed, because they had their regular responsibilities on top of the Sex Now responsibilities and then their agency would fund the material costs… in very few cases did the agency actually hire a support for whoever they had tasked with implementing Sex Now within their own agency… ideally, in a perfect world where money’s not an issue, do both, like give the agency money and have a support person attached to the agency or at least the region. (CBRC Staff)
	2. Networks and Communications	It started from going to Manitoba, and after each of these events there was a phone call to make sure that people get to provide that feedback, what worked well for them and what didn’t work well from them. We stayed in the background because we were the last one and we actually learned quite a bit from other sites (Site Coordinator)
5. Outer Setting	1. Patients’ Needs and Resources	So also understanding how HIV testing can be quite inaccessible for some people, so I think that was a really great – that we were able to actually offer that option during Pride weekend. And the other thing in terms of the Hepatitis C screening, we also know that access to Queer friendly, gay friendly physicians may not be… they may not be as accessible to certain segments of our community (Site Coordinator)
	2. Other	If people hadn’t been hydrating, it was more challenging to collect a sample […] We had limited shade, we had limited tent space or things like that for participants. (Site Coordinator)