FormalPara Key Points for Decision Makers

Qualitative interviews with 55 participants explored perceptions towards and acceptance of prophylactic human immunodeficiency virus (HIV) vaccination in three adult populations in the United States: the general population, ‘at-risk’ individuals, and parents/caregivers of children aged 9–17 years.

Key considerations/barriers included perceived susceptibility, i.e. whether participants felt there was a risk of contracting HIV (discussed by 90%); the clinical profile of the vaccine (e.g. the adverse effect profile [98%], and vaccine efficacy [85%], cost [73%] and administration schedule [88%]); and concerns around potential vaccine-induced seropositivity (VISP; 62%).

Understanding these factors could help develop HIV vaccine research strategies and contribute toward public health messaging to support future HIV vaccination programs.

1 Introduction

Human immunodeficiency virus (HIV) is a retrovirus that attacks the body’s immune system, thus weakening the body against other infections and illnesses. When left untreated, HIV progresses to acquired immune deficiency syndrome (AIDS), a collection of related illnesses that occur once HIV has caused significant damage to the immune system [1, 2]. Despite advances in the prevention and management of HIV, there is still a high number of people acquiring and living with the virus worldwide. The Joint United Nations Program on HIV/AIDS (UNAIDS) estimates that 1.3 million people worldwide acquired HIV in 2022 and that approximately 39 million people worldwide were living with HIV in 2022 [3]; at the end of 2023, the corresponding figure in the United States (US) was approximately 1.2 million people [4].

The median prevalence of HIV infection worldwide among adults aged 15–49 years has been estimated at 0.7% [3]. However, certain groups remain at higher risk of contracting HIV. For instance, sex workers, people who inject drugs, men who have sex with men (MSM), and transgender women and their sexual partners accounted for 70% of HIV infections globally in 2021 (with a prevalence of 12%, 10%, 21%, 2% and 25%, respectively [3], despite accounting for <5% of the global population [3]. In the US, the estimated prevalence of HIV infection among transgender women was 14.1% in 2006–2017 [5] and 42% in 2019–2020 [6]. A recent analysis of data from transgender women in the eastern and southern US provided an HIV incidence of 5.5 (95% confidence interval [CI] 2.7–8.3) per 1000 person-years (highest among Black participants: 19.3 [95% CI 8.4–30.2] per 1000 person-years) and an overall mortality rate of 3.3 (95% CI 1.5–6.3) per 1000 person-years (highest among Latinx participants: 9.9 [95% CI 3.2–23.1]) [7]. The high-risk groups vary globally; for example, new diagnoses in 2021 were most common among women and girls in Sub-Saharan Africa, among MSM in the US and Central/Western Europe, and among people who inject drugs in Eastern Europe and Central Asia [8]. In the US, race and ethnicity are other key factors; African Americans and Hispanics/Latinos are disproportionately affected compared with other racial and ethnic groups [9]. However, it should be noted that individuals’ risks vary considerably within populations, depending on individual behavior and the characteristics of their sexual partners.

The National HIV/AIDS strategy reflects the US governments’ commitment to bring the HIV epidemic to a halt by 2030, by reducing new HIV diagnoses by 90% [10]. Several effective HIV prevention methods are available, including the use of condoms and pre-exposure prophylaxis (PrEP), which is recommended for people in the ‘at-risk’ groups [10, 11]. PrEP is available as a daily oral pill and more recently as an every-other-month injection [11, 12], and has been shown to be well tolerated and effective, including in MSM, serodiscordant couples, and people who inject drugs [13, 14]. Several qualitative studies have explored the psychosocial impact of PrEP on the life of users, providing evidence of reduced stress and anxiety about contracting HIV and increased relationship harmony. However, PrEP uptake remains low and of approximately 1.2 million people indicated for PrEP in the US in 2019–2021, only 30% were receiving it, according to the latest HIV Surveillance System data [15]. Furthermore, adherence to PrEP, in particular to the daily pill, is an issue, primarily because of the difficulty with remembering to take the medication [16]. Despite recent availability of the every-other-month long-acting injectable option, long-term adherence to prevent future HIV acquisition can therefore be challenging [10, 17]. Another option is on-demand PrEP, which has been shown to provide effective protection against HIV infection in MSM [18, 19] but not in women [19], who need higher/more stable blood titers of PrEP to ensure adequate protection. Although the Centers for Disease Control and Prevention (CDC) provides information on how to correctly use the ‘2-1-1’ schedule, this approach is not approved by the US Food and Drug Administration (FDA) and is not recommended by the CDC [20].

The development of an effective prophylactic HIV vaccine that requires less frequent administration could address these challenges, thereby providing protection for ‘at-risk’ individuals and, potentially, the general population. A prophylactic HIV vaccine would thus limit future transmission and contribute significantly towards reduced disease prevalence and the attainment of national strategic goals. Several clinical trials have tested HIV-1 vaccine candidates worldwide; however, the high genetic diversity and propensity for immune evasion of HIV-1 have challenged the development of safe, potent vaccines with durable protective efficacy. A phase III trial conducted in Thailand to test a prime-boost regimen was the only study to show modest efficacy (31.2%) in reducing HIV-1 transmission [21]. More recent trials based on similar but improved vaccine regimens have displayed disappointing results. An alternative promising approach relies on the ability of vaccines to stimulate the immune system to produce broadly neutralizing antibodies (bnAbs) based on experiments with infusion of anti-HIV bnAbs [22, 23]. Recently, a germline-targeting HIV nanoparticle vaccine induced a robust immune response in helper T-cells for most recipients [24].

As has been well-documented across a range of conditions, including human papillomavirus (HPV) and, more recently, coronavirus disease 2019 (COVID-19) [25,26,27], adverse events, mistrust in public authorities, and limited condition-specific knowledge can all contribute toward an apprehension about receiving immunizations [28]. Vaccine hesitancy has been described as complex and context-specific, varying across vaccines [29], and can be particularly prevalent in parents/caregivers [30]. In 2019, the World Health Organization placed vaccine hesitancy in the top 10 global public health threats [31]. Conversely, perceived safety, efficacy and benefits of the vaccine, adequate information and reliable sources of information, health-related factors (e.g. being immunocompromised and having received any vaccine in the prior 5 years) and socioeconomic factors (e.g. higher income and socioeconomic status) have been shown to facilitate vaccine acceptance [32].

Capturing perceptions of those in the general population, as well as parents/caregivers and ‘at-risk’ individuals who may possess novel concerns, is necessary to identify the key drivers and barriers to potential HIV vaccination. Looking beyond the individual and viewing decision making within the context of the communities and populations they exist within would also elucidate concerns specific to an HIV vaccine and inform how wider issues can influence acceptability. Identifying the most important concerns would highlight areas that require the most attention for policy makers and decision makers alike to encourage vaccine uptake.

The objective of this qualitative study was therefore to explore the perceptions towards prophylactic HIV vaccination across three key samples in the US: adults in ‘at-risk’ communities and subpopulations, adults not considered at increased risk (the general population), and parents/caregivers of children aged 9–17 years. The general population was chosen to explore their interest in receiving a vaccine, and parents/caregivers to understand the perspectives of those who would be deciding whether to vaccinate their children. We aimed to develop a conceptual model (i.e. a pictorial representation of the concepts [barriers and drivers] identified as important to participants) to facilitate, for example, the development of a clinical outcomes assessment (COA) measurement strategy to evaluate the impact of an HIV vaccine on people’s lives, and the development of programs or policies to overcome barriers.

2 Methods

2.1 Study Design and Setting

This study used a qualitative approach to capture perceptions towards and acceptance of prophylactic HIV vaccination in three adult populations in the US.

2.2 Sample

A purposive sample of adults, aged 18–60 years, residing in the US, who had not been diagnosed with HIV (and therefore would be eligible to receive a prophylactic HIV vaccine) were recruited according to the eligibility criteria summarized in Table 1. Quota sampling was used to obtain representation from the groups of interest, including adults considered at greater risk of HIV in the US (including MSM, transgender individuals, gender-nonconforming individuals, individuals in a sexual relationship with a person living with HIV, and individuals currently taking PrEP), adults in the general population, and parents/caregivers of children aged 9–17 years.

Table 1 Eligibility criteria
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2.3 Procedure

Interviews were conducted between April 2020 and December 2020. All participants were recruited by a specialist recruitment agency, predominantly via social media. Participants completed a demographics form; if they self-reported as being in one of the groups of interest, they were invited to participate. Then they reviewed an informed consent form and were given time to consider their participation in the study. All participants provided written informed consent to participate ahead of the interview scheduling; verbal consent was also confirmed at the start of each interview.

A semi-structured interview guide was developed by the study team to facilitate the interviews and explore multiple topics with participants. Key topics included decision-making factors that participants would consider if there was an opportunity to receive an HIV vaccine, such as the balance between desirable and undesirable effects of vaccination (both biomedical and sociopsychological), perceptions of their individual risk of HIV, the implications of different administration methods or schedules, and practical considerations such as cost and the locality of vaccine centers. All participants were also read a short, educational explanation to establish basic information about HIV and vaccination to allow full participation in the interview. The interview guide included open-ended questions and probes (used to follow-up without leading the participants) to facilitate discussion around the key topics of interest, such as:

  • What do you think might be some benefits of receiving a vaccine for HIV, if any?

    1. o

      For example, would there be any benefits to your yourself?

    2. o

      For example, would there be any benefits to other people?

  • What do you think might be some of the negatives of receiving a vaccine for HIV, if any?

    1. o

      Would there be any risks to yourself? Tell me about that?

    2. o

      Do you have any worries about what other people might think or say if you got vaccinated against HIV? Tell me about that?

At the end of the discussion, participants were asked: “Overall, how likely do you think you would be to get vaccinated against HIV?” (or how likely they would be to get their child[ren] vaccinated).

All interviewers were trained and experienced in qualitative interview techniques and hold certification in Collaborative Institutional Training Initiative (CITI) Human Subjects Research. Interviews lasted approximately 60 min and were conducted via online software (WebEx/Teams) or telephone. All interviews were audio-recorded and transcribed verbatim.

2.4 Analysis

A directed content analysis approach [33] was used to explore participant feelings, perspectives and perceptions, while following two existing models of health behavior to guide interpretation. The health belief model, which outlines key predictors of illness prevention behavior, was used to guide interpretation of the proximal drivers and barriers reported by participants [34]. For more distal factors, and for HIV-specific considerations, Kaufman’s socioecological model of HIV prevention was followed [35]. The model not only identifies individual factors such as emotions and risk perception but also indicates that factors beyond the individual should be explicitly explored when thinking about behavior change, including interpersonal networks, the community, and institutions.

First the interview transcripts were read thoroughly, allowing the analysts to immerse themselves fully in the data and to redact any identifiable information. Participants were assigned a code to protect their identity, comprising a unique numerical identification (ID) and indication of the participants’ relevant demographic subgroup(s): ‘AR’ for members of ‘at-risk’ groups, ‘GP’ for members of the broader ‘general population’, and ‘PC’ for participants who are also parents/caregivers of children aged 9–17 years and were able to speak about the potential vaccination of their child(ren). Transcripts were then uploaded into ATLAS.ti v7. The analysts applied descriptive codes to quotes in the transcripts, and grouped the codes into domains (categories), following the concept names included in the two theoretical models where applicable. Multiple analysts independently coded the transcripts, and analysts met regularly to discuss the coding and the data; codes were refined iteratively with codes added, merged, and re-named throughout. The identified concepts were synthesized into a conceptual model, which was developed to visually depict pertinent barriers and drivers for and against HIV vaccination in participants. Design of the model closely followed that of Kaufman’s socioecological model of HIV prevention [35].

Conceptual saturation [36] was used to indicate whether sufficient data had been collected and to reasonably conclude that perceptions had been understood to an appropriate depth and breadth, by defining the point at which no new concept-relevant information was identified. Saturation was conducted at a subgroup level as it was anticipated that different concepts would be relevant within the three groups. For each subgroup, interview transcripts were grouped into four sets containing an equal number of transcripts in sequential order, and elicited data were compared between sets. Upon a new concept being identified, previous interviews were retrospectively reviewed to ensure that the concept had not been inadvertently missed in previous coding efforts [37].

3 Results

3.1 Sample

The distribution of participants across subgroups is provided in Table 2. The sample characteristics are shown in Table 3. The total sample (N = 55) included 23 in the considered ‘at-risk’ subgroup, 32 in the general population subgroup, and 23 in the subgroup of parents/caregivers of children aged 9–17 years. These categories were not mutually exclusive. For example, an individual could be in both the at-risk subgroup and the parent/caregiver subgroup. The sample was diverse in terms of age, race, ethnicity, education level, and geography. Gender diversity varied across subgroups; most participants identified as female in the general population (84%) and parent/caregiver (83%) subgroups, while in the ‘at-risk’ subgroup, 70% identified as male and 24% identified as non-binary/other gender.

Table 2 Distribution of participants across subgroups
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Table 3 Sample characteristicsa
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3.2 Saturation Analysis

Overall, it was considered that saturation was met for this study. For each subgroup, all included concepts were deemed to be fully understood in terms of depth and breadth. Saturation tables are provided in the Online Resource.

3.3 Conceptual Model

The conceptual model is shown in Fig. 1.

Fig. 1
figure 1

Conceptual model of HIV vaccine perceptions

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3.3.1 Individual

Individual-level factors comprised individual perceptions, beliefs, or emotions that affected participants’ perceptions and hypothetical decision making for uptake of an HIV vaccine.

3.3.1.1 Perceived Clinical Benefits/Barriers

Perceived clinical benefits, such as treatment efficacy, were a common sentiment among participants. Most participants (85%) stated that they would like to know more about how effective an HIV vaccine would be before receiving it. PrEP users would prefer to know how a potential vaccine’s efficacy would compare with that of PrEP.

  • “If it’s something that is basically guaranteeing me that I won’t get [the disease], then yes, I would definitely be open to having that vaccine”. (GP-08)

  • “To see if it’s more effective than just staying on PrEP”. (AR-123)

Perceived clinical barriers such as adverse effects, vaccine-induced seropositivity (VISP; the detection of vaccine-induced HIV antibodies in the absence of HIV infection and thus the risk of a positive HIV test result following vaccination [38]), and administration concerns were a predominant theme. For example, when asked to consider the biomedical implications of a vaccine, adverse effects were perceived as a potential risk by almost all participants (98%). Advance knowledge of which adverse effects may occur would be preferred. Long-term adverse effects, such as permanent immune damage, were of greatest concern to participants, and just over one-third of participants (37%), including half of the interviewed caregivers of children aged 9–17 years (52%), reported that they were more comfortable receiving or giving their child(ren) a vaccine that had been marketed for a longer period of time versus a vaccine that had only recently been approved for use, and therefore had a larger body of supporting evidence to support its efficacy and safety. Participants who were PrEP users remarked that they would like to know how an HIV vaccine would compare with PrEP in terms of adverse effect profile, so that they could determine which approach would be more suitable for them. Conversely, one participant was indifferent to the adverse effect profile of a potential vaccine, stating that risk of death from HIV is greater than any potential adverse effect.

  • “… You know, what are the side effects? Are they causing long-term effects later in life that we may not realize was caused from these vaccinations?” (GP-PC-05)

Many participants expressed concern about VISP (64%) and worried how a routine test could potentially give a positive HIV test result due to the induction of anti-HIV immune response, which could be misinterpreted and would impact their lives. Predominantly, participants were fearful of experiencing stigma if others, such as potential partners, other members of the community, and healthcare providers, learned they had received a positive HIV test result. Participants were also concerned that seeing a positive test result could affect them emotionally, and could cause them to question how they could subsequently ever know if they ever did contract HIV. Overall, 35 participants (n = 35/55 [64%]) reported concerns about VISP. They were more likely to be caregivers discussing concerns about vaccinating their children (18/23 [78%]) than members of the general population discussing vaccinating themselves (21/32 [66%]), or at-risk individuals (12/23 [52%]).

  • “I think that would make me really nervous. I think that would make me uncomfortable … I would be afraid that … what if the vaccine didn’t work? I think that I would see the positive result and I would immediately think that I was positive …” (AR-117)

  • “I wouldn’t feel safe or protected after getting it, because how would I know? You know what I mean? […] if you keep testing positive, how do you know that you have it versus it’s just what’s in your body from the vaccine?” (GP-PC-19)

  • “People who might have been willing to have sex with me, might be scared away simply for the fact of testing positive after [receiving the vaccine].” (GP-13)

The administration schedule of the vaccine was also discussed. Attendance at multiple appointments and/or the receipt of multiple injections were perceived as a deterrent, particularly for participants in the general population subgroup (72%). However, some ‘at-risk’ individuals perceived the reduced administration schedule relative to daily PrEP (when taken as a pill) as a potential benefit, given the long-term nature of PrEP and difficulties remembering to take their daily dose.

  • “If I had to go out of my way to do it multiple times, I think that would be a very big barrier for me personally.” (GP-16)

  • “I would not have to be worried, err, about did I take it, or did I not take it?” (AR-152)

An additional potential barrier, named by three participants who were current PrEP users, was the process for discontinuation of their current treatment, ahead of receiving the vaccine. These participants noted they would require more information before they could make a decision.

  • “I would be curious about the transition from PrEP to, to the vaccine, I mean, what that tapering off of the medication might look like, or whether it’s just stopping it.” (AR-124)

3.3.1.2 Perceived Vaccine Benefits

Perceived vaccine benefits were also identified as influencing perceptions and decision making. Almost all participants (98%) stated that protection from HIV would be a benefit. There was also a notion of experiencing ‘peace of mind’ from receiving a vaccine.

  • “Something else … in my bag of tricks … that keeps me from, you know, contracting the virus.” (AR-169)

  • “I think, as a parent, it would ease our mind.” (GP-PC-34).

Some participants reflected on the lifestyle benefits of receiving a potential HIV vaccine and how this could potentially impact on access to institutions, services, and travel in the future.

  • “I know there are some establishments that require certain types of vaccines.” (GP-16)

A small number of participants (16%), most of whom (89%) were in the ‘at-risk’ subgroup, noted that receiving a vaccine could improve their relationships/sex lives as they would not need to worry about the risk of HIV from a new partner.

  • “I would feel like it would take, um, stress away from the relation – any relationship.” (AR-153)

3.3.1.3 Perceived Susceptibility

Perceived susceptibility substantially impacted participants perceptions and potential decision making; over 90% of participants in the general population and parent/caregiver groups considered how susceptible they felt they/their child(ren) were to HIV when considering whether they may receive an HIV vaccine. Parents/caregivers of children aged 9–17 generally felt their children were not susceptible as most were ‘too young’ to be sexually active and thus at risk of HIV infection but would actively consider vaccination of their child(ren) in the future as circumstances changed.

  • “I’m not particularly concerned at the moment. They’re both, um, young enough that they’re not having sex.” (GP-PC-31)

Some participants felt that HIV could be adequately prevented by methods such as safe sex and the avoidance of at-risk behavior such as intravenous drug use, and that this was sufficient for themselves/their child(ren), meaning they were less likely to take up a vaccine. However, the possibility of an unexpected event in either their own or their child(ren)’s life (such as a blood transfusion) and the role it could play in HIV transmission was acknowledged by some parents/caregivers.

  • “I’m married, and I only have one partner. But besides that, let’s say if that changes at some point in my life, I feel like I would try to be responsible and even if I’m having different sexual partners, I think I would try to be mindful about my behavior and avoid the disease with that.” (GP-PC-56)

Some participants stated that the prevalence of HIV in their community would influence their decision to receive a potential vaccine. Factors discussed included race/ethnicity, home town, and employment type.

  • “… they say African-Americans are at a higher risk and, it’s a lot of cases here in [state].” (GP-PC-05)

  • “I work in the health field and there’s always that – you know, no matter how safe I am, there’s always a chance of my glove ripping.” (GP-PC-49)

3.3.1.4 Altruism

Altruism was an individual factor for one-third of participants (33%), who stated that they would consider receiving a vaccine for not only their own benefit but also for others – noting they could ‘lead by example’ and encourage higher vaccination rates, and/or how mass vaccination could lead to herd immunity. Discussion of altruism was particularly prevalent in the ‘at-risk’ subgroup (52%) but uncommon in the parent/caregiver subgroup (4%), where only one parent/caregiver mentioned this in terms of their decision to vaccinate their child.

  • “You’re doing your part for humanity.” (AR-127)

  • “The normalization of getting a vaccine and talking about it and being vaccinated, I think is a big benefit because it reduces stigma or fear amongst others who are more at risk. So, I do think that’s a huge benefit.” (GP-PC-32)

3.3.1.5 Perceived Severity of Human Immunodeficiency Virus (HIV)

Perceived severity of HIV, i.e. the extent to which participants viewed HIV as a serious disease, also impacted individual decision making. Participants who were particularly concerned with the fact that HIV is incurable and can be fatal if left untreated were more likely to highly value protection from a vaccine.

  • “If you get, you do have forever, and although it is more manageable now, and people can actually live long, healthier lives with it, it’s still nothing that you want to have.” (GP-PC-34)

3.3.1.6 Distrust in Healthcare and Pharmaceutical Companies

Distrust in healthcare and pharmaceutical companies was discussed by 24% of participants, who described how the content of the vaccine may be susceptible to malicious tampering, or they questioned the financial motive behind vaccine development.

  • “They’ll create, um, different prescriptions, err, to profit off of individuals, err, which is concerning.” (AR-145)

3.3.2 Child-Specific Concepts

Child-specific concepts also influenced decision making for parents/caregivers of children aged 9–17 years. Some (39%) stated that their child(ren)’s perspective on HIV vaccination would affect any subsequent decision made, with one participant saying they would “leave that in their hands” (GP-PC-24). Another caregiver was reluctant to discuss HIV with their child as they felt they were too young to be engaging in any risky behaviors.

  • “I don’t want to talk about HIV with my 12-year-old. I don’t think it’s necessary.” (GP-PC-36)

3.3.3 Interpersonal/Network

Interpersonal/network factors included dyadic and familial considerations around vaccination, such as social support and relationship satisfaction.

Social network support and trust impacted participants’ perceptions; participants noted that peer and family attitudes would contribute toward their decision to receive an HIV vaccine. However, most participants felt that a negative reaction from either peers or family would not deter them in a decision, and neither would stigma (71%).

  • “I think that now I’m old enough to make a decision for myself, um, and I don’t really know if people’s opinions would really affect what I thought about the necessity of the vaccine or not.” (GP-22)

Relationship satisfaction, support, and trust were considerations. Some participants (25%) stated that a vaccine would give their romantic/sexual partner ‘peace of mind’ (AR-PC-167) that they would also be unable to contract HIV. Relatedly, 13% believed that the degree of trust with their romantic partner would impact upon their perceived susceptibility to HIV and subsequent decision to receive an HIV vaccine.

  • “With just the same partner for so long, we already have built a relationship on, you know, pillars of trust.” (GP-PC-24)

Conversely, 11% of participants believed that seeking an HIV vaccine could damage their current or future relationships by raising doubts about fidelity for their partner. One participant remarked that it would ‘raise some concern’ (GP-03).

3.3.4 Community

Community factors included reflections on factors that influence HIV vaccination behavior at a community level, beyond the individual’s immediate social network. Social stigma and perceptions of judgment were a factor for 22% of participants. One participant worried they may be labeled as ‘promiscuous’ (GP-74) if they received an HIV vaccine, while one parent/caregiver worried that people would think they were negligent if they gave their child the vaccine as their child was “too young to be doing that to them” (GP-PC-07). However, most participants remarked that social stigma was not a fear for them and that it would not impact upon their decision to receive an HIV vaccine (67%). Social norms influenced some parents/caregivers (30%) who felt that if vaccines were “accepted by society” (GP-64) they would be more likely to vaccinate their child(ren).

3.3.5 Institutional/Health System

Institutional/health system factors included participants’ reflections on wider health systems and participants’ access to quality healthcare. Convenient, responsive services that could ensure quick and easy access to an HIV vaccine was pertinent to 35% of participants. One participant stated that if things aren’t “easy … to get and cheap, then I … turn my, my head to it” (AR-122). Institutional stigma was not a concern for most participants (64%), but 13% felt that an HIV vaccine on their/their child(ren)’s medical records could affect how they may be treated by the healthcare system, government, or other organizations.

  • “Would it, like, ruin his career? Would it stop him from getting to where he needs to school-wise?” (GP-PC-42)

3.3.6 Structural

Structural factors that could impact behavior, such as the economy and public policy, were considered by many participants. Costs of services and care would influence decision making for most participants (75%), who reported they would not be willing to pay for the vaccine if it was not fully covered by their insurance provider or if it was very expensive. Recommendations from trusted healthcare bodies were a consideration for 62% of participants, who stated that they had followed their doctors’ recommendations for previous vaccinations and would only receive/give their child(ren) an HIV vaccine if it was recommended by their doctor, the CDC, and/or the FDA. Public policy and laws were a consideration for around half of parents/caregivers of children aged 9–17 years, who noted that they had their child(ren) vaccinated in the past to comply with school admission rules, and thus would consider this factor.

  • “I follow whatever the guidelines are for vaccinations that my Doctor prescribes.” (GP-PC-36)

  • “If you don’t have their shots, it’s kind of, like, something they have to decide, like, if they’re allowed to go to school or not.” (GP-PC-47)

3.4 Overall Acceptability and Most Important Factors for Influencing Decision Making

Following discussion of all the factors that may or may not influence perceptions of an HIV vaccine and decision making around uptake, participants were asked to reflect on the interview and report whether they felt that they would vaccinate themselves/their child(ren) against HIV if a vaccine was available, and to note which key factors influenced that response. Overall acceptability is presented in Fig. 2; at-risk adults were more likely to vaccinate themselves than other participants.

Fig. 2
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Overall acceptability of an HIV vaccine. HIV human immunodeficiency virus

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The most commonly reported factor that would contribute to decision making was individual perceived susceptibility to HIV.

  • “The main driver for me would just be risk factor and my personal risk factor versus putting a fairly new medical thing into my body. I would, I would say to myself, okay, are you really worried about getting HIV? No. Okay, then why are you going to put this in your body? Because you don’t need it.” (GP-PC-19)

The second and third most identified factors that would contribute toward decision making were the potential adverse effect profile and the overall efficacy of a potential HIV vaccine.

  • “I guess the only thing that I will want to know, err, is just to make sure that it doesn’t – does nothing, as far as growth and, and being able to reproduce.” (GP-PC-38)

Other frequently reported concerns included cost, the administration schedule for the vaccine, and VISP.

4 Discussion

Conducted in the US, this study sought to understand perceptions towards and acceptance of prophylactic HIV vaccination in order to generate a holistic understanding of the factors that contribute toward decision making.

Participants discussed several individual-level factors that would impact their perceptions of a potential HIV vaccine. Perceived susceptibility was particularly important. However, it has been previously documented that perceived susceptibility to HIV is extremely low for those in long-term heterosexual relationships [39]. The clinical profile of the potential vaccine, including protective efficacy and adverse effect profile, was also an important consideration. Fear of adverse effects has previously undermined vaccination programs, including the HPV vaccine roll-out [40]. Furthermore, media reporting of vaccine-related incidents can amplify their potential danger and significantly reduce uptake, as demonstrated with the influenza vaccination program [41]. A particular factor for PrEP users was the relative efficacy compared with PrEP. Until an HIV vaccine is made available, it appeared difficult for PrEP users to fully assess the benefits and barriers of potentially receiving an HIV vaccine. Once a vaccine is available, effort should be made to address PrEP users’ specific concerns that may arise with a switch in treatment approach.

The risk of VISP was perceived as an important deterrent to a hypothetical HIV vaccine, conducive with previous research [42]. This was linked to stigma, especially how individuals would be perceived by others in the community, and also to the impact on their health insurance. Most parents/caregivers of children aged 9–17 years found potential VISP unacceptable for their child(ren), citing fears that their child(ren) would be treated differently as a result. Interestingly, while stigma factors into participants’ feelings toward VISP, overall, participants did not think that social or institutional stigma would impact their decision to receive an HIV vaccine. This was surprising given the plethora of evidence suggesting that stigma is a significant barrier to hypothetical HIV vaccination [43,44,45]. Participants in this study expressed the general feeling that socially, others did not need to know whether they had a vaccine or not, and only a minority (13%) were concerned about institutional stigma. Indeed, 64% of participants explicitly reported institutional stigma was not a concern. Furthermore, the risk of VISP caused a feeling of uncertainty in many participants, especially the majority of the parents/caregivers (78%), as seeing a positive test result could cause them to question how they could subsequently know if they ever did contract HIV. From a medical standpoint, people with VISP may not be promptly diagnosed with a true HIV infection, thus receiving delayed or no treatment and carrying an increased risk of transmission. Moreover, they may be unable to donate blood or organs and may undergo unnecessary medical follow-up and/or treatment. The presence of VISP may raise additional challenges to a person’s everyday life—they can be discriminated by employers and can be denied insurances and visa applications [46].

The primary perceived benefits of receiving an HIV vaccine included protection against HIV and the associated emotional relief that protection would provide. A prophylactic vaccine was perceived as potentially alleviating fear of contracting HIV. Additionally, receiving the vaccine was seen as beneficial not only for the individual but also for reducing risk and spread within the wider community. The notion of altruism is not new in HIV vaccine research. Participants included in an HIV vaccine clinical trial were highly motivated by societal gain [47, 48]. Fostering a sense of altruism could therefore encourage greater uptake of a potential HIV vaccine across populations.

Social norms were a consideration for parents/caregivers of children aged 9–17 years in particular, noting that if vaccinations were socially acceptable, they/their child(ren) would be more likely to receive a vaccine against HIV. This finding has been previously observed elsewhere, with adults more likely to receive a vaccine when uptake among friends, family and the general community is high [47].

Costs of services and care were a common concern, indicating that HIV vaccine uptake could be substantially impacted according to whether it was funded by insurers or paid out-of-pocket, and more broadly by the type of healthcare system that the individual resides in. Previous research has also noted that some drug users would not consider an HIV vaccine if it were to be funded from their own personal finances [48].

Limitations to this study are acknowledged. First, the interviews were conducted between April 2020 and December 2020 when the COVID-19 pandemic considerably influenced life and discourse within the US. Participant knowledge of both infectious diseases and vaccinations may have been influenced by this backdrop. Second, all participants were based in the US, and it is expected that attitudes and beliefs toward HIV and vaccination prevalence within the US and within the most ‘at-risk’ groups could substantially vary in other countries. Even within this sample, varied attitudes were observed. Third, participants were primarily recruited through social media advertising. The viewpoints of individuals who do not share the same access to information-rich resources, such as social media platforms, could have been missed. Fourth, while the sample overall included an appropriate representation of people of different genders, males were underrepresented in the ‘general population’ and ‘parents/caregivers’ subgroups, while females were underrepresented in the ‘at-risk’ subgroup. Our study timelines prioritized recruiting the appropriate number of participants, and it was not possible to wait longer for men to enroll. Finally, exploring perceptions and decision making related to a hypothetical vaccine may not capture the full range of concerns and concepts pertinent to participants. While this is unavoidable, if/when an HIV vaccine is approved, future research would be required to understand acceptability in context of the known vaccine profile.

5 Conclusion

The introduction of a prophylactic HIV vaccine would contribute toward global efforts to halt transmission of HIV; however, to achieve a successful vaccination program, broad uptake would be critical. The conceptual model developed from participant interviews in this study illustrates the breadth of factors that may influence individuals’ perception and acceptance of an HIV vaccine. Perceived susceptibility and vaccine profile appear most important to participants when considering whether they would receive a vaccine against HIV. Understanding the varied factors that influence perceptions and acceptance of vaccines could contribute toward successful introduction of potential HIV vaccines in the future. Our findings may contribute toward the design of appropriate public heath interventions and messaging related to future HIV vaccine programs, and inform important experiences or COAs to measure in future clinical trials and related research.