Table 2.

Themes and exemplar quotes, by CFIR domain and construct

CFIR Domain	CFIR Construct	Theme		Exemplar Quote
Innovation	Evidence-base	Facilitators	Evidence of the COVID-19 vaccines’ effectiveness	I think the vaccine is effective for preventing severe illness and death from COVID.
	Complexity	Barriers	Storage and management requirements of the COVID-19 vaccines	We need to make sure that the refrigerator is monitored, and the temperature doesn’t go up or down too drastically.
Outer Setting	Partnerships and connections	Facilitators	Established partnership with the Department of Health	The public servants at the Department of Health have always been very supportive of the type of work that we do.
	Financing		Existing funding that could be leveraged to support COVID-19 vaccine-associated costs	We could order [the vaccine] for free from the Florida Department of Health.
	Local attitudes	Barriers	Politicization of the COVID-19 vaccines	[Specific public officials] were at [the SSP] but we didn’t mention our COVID vaccination partnership because of the non-belief in vaccines from the political appointees.
	Policies and laws		Policies governing vaccine storage, management, and administration	You have to be a medical assistant or a nurse or a doctor to administer the vaccines…it’s against the law for me to give vaccine.
Inner Setting	Recipient-centered culture	Facilitators	Established foundation of trust between the SSP and PWID	We meet them where they’re at, regardless of what they’re doing, how they’re doing, with a level of love and care, which creates a trust factor.
	Mission alignment		Alignment with organizational goal of serving as a “one-stop-shop”	They can access everything. It’s a one-stop shop here. I think that makes it easier for them.
	Compatibility		Existing services and research studies for alignment and/or integration	The COVID-19 vaccine could be offered alongside [syringe] exchange, at the weekly health clinic, or on the mobile unit.
	Tension for change		Consensus about the need for new approaches to reach PWID with the COVID-19 vaccines, and the relative advantage of doing so through the SSP	We tend to provide things to people in a setting that is as comfortable as possible for them… It doesn’t look like a clinical setting with people looking down at them.
	Relative priority	Barriers	Competing organizational priorities	[The COVID-19 vaccine initiative] is not something as staff that is on the top of our agenda.
	Available resources		Personnel shortages	We need more people because one person can’t be at 10 places.
	Relational connections		Segmentation of roles and responsibilities	Everyone has their tasks that they need to hit, so maybe sometimes that kinda gets in the way of being a little more, I guess, well-rounded.
	Communications		Limited internal staff communication across services/research studies	A lot of us don’t know half of what’s really going on, research studies or things being implemented.
Individual Characteristics	High-level leaders	Facilitators	Influential decision-makers	Have you heard the Ariana Grande song? ‘I want it, I got it.’ I want it, so… [laughter].
	Implementation leads, Motivation		A clear champion	It took the self-efficacy of one person [to get] everything done.
	Other implementation support	Barriers	Lack of ownership among staff members not directly involved in delivery of the vaccines	Personally, I don’t feel, like, very responsible, or…that involved in, like, making it a success.
	Innovation deliverers, Capability		Limited personnel with the technical skills to manage and administer the vaccines	Since there’s only one person that can do it, if he’s not here, then that means…they can’t get it. That happens pretty frequently.
	Innovation recipients, Opportunity		Higher order needs	The biggest thing is just the competing survival, mental health, and the substance use disorder. Our participants, as soon as there’s a barrier it feels unsurmountable.
	Innovation recipients, Motivation		Limited perceived susceptibility to COVID-19	Many PWID don’t believe that COVID-19 could cause them any damage, because of where they’re at in their own lives.
			Misinformation about COVID-19 and the COVID-19 vaccines	Most people have a conspiracy theory idea behind COVID. They’re tryin’ to microchip us, or…that they’re tryin’ to wipe all the HIV positive people out.
Implementation Process	Doing	Facilitators	Adaptive and flexible approach to implementation	At [our SSP], we’re always making changes and always adapting. I think like every week it’s something new or something different.
	Engaging innovation recipients		Transparent and consistent communication about the COVID-19 vaccines with PWID	We don’t force it. We tell them whatever they’re more comfortable with and remind them that we’ll always have vaccines available on site if they choose, later on.
	Engaging innovation deliverers	Barriers	Limited internal staff communication about the COVID-19 vaccines	I haven’t gotten any updates about whether or not it’s progressing or whether or not they needed to find more people. That coordination piece, I have not seen.
	Teaming		Limited involvement of the peer navigators and/or outreach workers and the mobile unit	Definitely [the peer navigators and/or outreach workers], they could communicate. Since they handle a lot of participant’s medications, that’s also a sense of trust there that they develop with the participants.
	Adapting		Tension between increasing vaccine uptake and reducing waste	Before when it started, we would…schedule around maybe six until those six would come. Now if only one comes or two show up, we’ll administer that to just that one or two, rather than wait for those six. We’ll just discard the rest.
	Assessing needs of innovation recipients		Lack of compensation	Pay them for their time…That takes away the competing priority. They don’t have to hustle for that half hour. They can follow through on what they want to for their health.