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date: 07 December 2023

Homelessness and Vaccination Strategies: Problems and Potential Solutions to Vaccinate Vulnerable Populationsfree

Homelessness and Vaccination Strategies: Problems and Potential Solutions to Vaccinate Vulnerable Populationsfree

  • Elena Mitevska, Elena MitevskaCumming School of Medicine, University of Calgary
  • Priyanka GillPriyanka GillCumming School of Medicine, University of Calgary
  •  and Monty GhoshMonty GhoshGeneral Internal Medicine, University of Alberta


People experiencing homelessness (PEH) are at a higher risk of vaccine-preventable illnesses. They have higher rates of chronic illnesses that predispose them to communicable diseases, and this is compounded by poor access to sanitation. While vaccination is especially important in PEH, they tend to have lower rates of vaccine uptake compared to the general population. Factors impacting this discrepancy include difficulty accessing vaccines and public health programs, lack of access to primary care services, and distrust of the health care system. Despite this, there is evidence to suggest that many PEH are accepting of vaccinations and are willing to get vaccinated provided the right approach and interactions. Understanding client-specific barriers along with education and counseling are key to improving vaccine uptake in PEH, and programs targeted specifically at PEH can improve vaccine uptake and ultimately the health of PEH.


  • Behavioral Science and Health Education
  • Infectious Diseases
  • Special Populations


There are multitudes of definitions to describe people who experience homelessness (PEH). Broad definitions often include individuals who are unstably housed, indigent, and living in a shelter or on the streets. These living conditions, in addition to factors such as substance use, place PEH at a higher risk of vaccine-preventable illnesses such as Hepatitis B (Altice et al., 2005). They also have higher rates of chronic health conditions (such as asthma and chronic obstructive pulmonary disease) predisposing them to influenza infection and other communicable pathogens (Story et al., 2014). Exposure to transmissible illnesses and infectious pathogens are often compounded by the living conditions PEH experience, including exposure to harsh weather if living outside, crowded areas if living in shelters, and overall poor access to sanitation and hygiene resources, which ultimately pose additional risks for succumbing to certain preventable diseases (Wood, 2012). With COVID-19 in particular, PEH were also 20 times more likely to require intensive care and 5 times more likely to die following infection than the general population. Additionally, many do not have access to primary care services (Ghosh et al., 2021). These factors highlight the increased importance of vaccination in this population. Despite this, PEH tend to have lower rates of vaccine uptake when compared to the general population. For example, Story et al. (2014) found that only 23.7% of the eligible homeless individuals they surveyed received their influenza vaccines, compared to 53.2% of the population eligible to receive influenza vaccines in the United Kingdom. Data during COVID-19 demonstrated similar concerns with vaccine uptake, with data demonstrating 47.7% uptake with two vaccine doses in vulnerable populations (Shariff et al., 2022).

There are several factors contributing to the vaccine uptake discrepancy between PEH and the general population, with a major contributor being lack of access to vaccines and public health programs that specifically target PEH. Difficulties in ensuring that PEH have access to vaccines include negative attitudes toward this population, especially toward people who inject drugs, as well as logistical difficulties in administering multiple doses of a vaccine, and financial restrictions (Altice et al., 2005). Access to primary care or other clinics where vaccines are administered can also be a barrier.

Even in the face of barriers, there is evidence to suggest that most PEH are accepting of vaccination (Altice et al., 2005). Indeed, 75% of the homeless population surveyed by Story et al. (2014) were willing to get vaccinated if offered and provided. Given the various barriers to providing vaccines to this population, additional strategies to increase the accessibility and administration of vaccinations for our homeless populations are required. Indeed, given the impact of COVID-19, determining best approaches to provide vaccines to this population and ensuring adequate uptake and acceptance is key.

PEH face many physical and systemic barriers to being vaccinated, ranging from ineffective access to distrust of the health care system. When examining these barriers, we see that vaccination nonadherence comes in two identified forms, unintentional nonadherence and intentional nonadherence (Beers et al., 2019). Unintentional nonadherence is when specific barriers impede individuals from accessing care, including forgetfulness, structural barriers, and knowledge barriers. With intentional nonadherence, individuals intentionally avoid vaccination through active decision-making. Several factors that aim to facilitate vaccine adherence have also been identified. Of note, Individuals Experiencing Homelessness (IEH) are heterogeneous in nature, encompassing different groups with different needs, varied based on age group and location. The following guidance only offers to highlight general principles around vaccinating IEH but may not necessarily encompass all aspects pertaining to specific subgroups.

Unintentional Nonadherence

Misinformation and the Need for Improved Provider Counseling and Education

One of the main barriers to vaccination is misinformation as well as a lack of or limited vaccine information (Asgary et al., 2015; Doroshenko et al., 2012). Lack of knowledge around the importance of vaccines is a common theme. For instance, a 2015 study found that women who experience homelessness lack knowledge around certain vaccines such as human papillomavirus and the preventative relationship of the vaccine to cervical cancer in comparison to the general population (Asgary et al., 2015). This knowledge gap extends to difficulties understanding the differences between the variety of vaccines available, with confusion around which vaccines people experiencing homelessness (PEH) may have already received and which ones are pending, as well as confusing vaccines for other forms of medical interventions such as antibiotics (Doroshenko et al., 2012).

There can also be frank misunderstandings around the role of vaccines. One study determined that PEH believe that vaccines, rather than being protective against certain illnesses, actually cause infections (Washington-Brown & Cirilo, 2020). Another study found that some PEH believe that vaccines cause the flu (Lorenz et al., 2013), while yet another demonstrated that some PEH believe that vaccines were unsafe in general and have significant side effects (Bryant et al., 2006; Koniak-Griffin et al., 2007). This was compounded by individuals who may have had negative experiences or reactions to a vaccine. These experiences were often shared with other PEH, further influencing their willingness to obtain future vaccines and increasing much of the existing mistrust PEH have with the health system (Metcalfe & Sexton, 2014). Last, there is a fear of needles and disliking of injections, especially among youth, and this can also interfere with injection uptake (Doroshenko et al., 2012).

Education and counseling are key in improving vaccine uptake in PEH, and inversely, an inadequacy or lack of these key components adversely affects uptake. Education and counseling should be conducted through the entire process of information gathering, vaccine administration, and post–vaccine care (Asgary et al., 2015). Improved information and direct communication from providers can help reduce vaccine hesitancy and support preventative care (Elnicki et al., 1995).

Education must also be provided in a manner acceptable to clients in a level appropriate to them. Ideally, education should be provided with narrative health materials to help add context to the suggestions (Gallardo et al., 2020), along with low-literacy simple education tools including picture-based resources (Jacobson et al., 1999). Last, demedicalized dialogue with the community and PEH can ensure appropriate understanding of the need for vaccines (Metcalfe & Sexton, 2014). In regard to what education should be provided, clients were more likely to acknowledge that vaccines were a key form of preventative interventions when they had a good knowledge of infectious diseases and recognized the risks they face when in transient living conditions (Doroshenko et al., 2012). In order to combat misinformation, myth busting should be done where possible to ensure that false narratives, often portrayed in the media, can be adequately addressed.

Structural Barriers Including Lack of Access to Immunization Services

Convenience and extent of vaccine availability are two crucial aspects of improving vaccine uptake. The lack of availability of vaccine sites and clinics, as well as not meeting clients where they are at, reduces their likelihood of obtaining a vaccine (Koniak-Griffin et al., 2007). In addition, referral to vaccination clinics away from familiar settings often results in lower uptake (Amesty et al., 2008). Clients have difficulties reaching vaccine clinics due to limited transportation availability as well as receiving limited information on how to reach vaccine clinics, including where these clinics are located (Metcalfe & Sexton, 2014). Other barriers that have been identified include a lack of communication devices and means. It can be difficult for clients to get a vaccine because they are unable to book appointments or be reached for an appointment because they do not have a phone, mobile device, or Internet access. Additionally, clinics that service these clients often do not have the support or capacity to carry out large vaccination campaigns. Staffing constraints and competing priorities regarding clinic function often limit the ability for clinics, which service these populations, to provide vaccines (McKee et al., 2018; Sneller et al., 2008).

A tried and tested strategy is bringing services to where clients are at as opposed to expecting them to reach services in the community. PEH often have significant priorities unrelated to immunization, including managing food insecurity and finding shelter, inhibiting their ability to obtain a vaccine (Doroshenko et al., 2012). While these barriers are difficult to overcome, bringing services to this population is enormously helpful.

Other structural barriers in obtaining vaccines include data keeping and tracking regarding vaccination status. Recordkeeping for PEH is often irregular given the transience of the population and the infrequent interaction they have with health services. Often the inability to track down someone’s vaccination status and opting to delay providing a vaccine while this is determined may be a missed opportunity because the client may be lost to follow-up (Washington-Brown & Cirilo, 2020). Additionally, immunization records may be incomplete (and PEH may be hesitant in disclosing personal information such as their name or date of birth), which can cause hesitancy in health providers to administer the vaccine (McGee et al., 2021; McKee et al., 2018). Efforts must be made to ensure that accurate and up-to-date recordkeeping is maintained when working with PEH.


Within private health care systems, cost is a large barrier to obtaining care (Elnicki et al., 1995). Many PEH believe that vaccinations can only be obtained if they have private insurance (Washington-Brown & Cirilo, 2020). Indeed, many lack the appropriate funds and insurance to support independent vaccination accrual, but every effort must be made to ensure they have free access to life-saving preventative interventions (Metcalfe & Sexton, 2014; Redlener, 1993). While cost can be a barrier to obtaining a vaccine, monetary incentives have been shown to improve vaccination rates in PEH, making them a powerful tool to improve vaccination rates among PEH (Wood, 2012).

Appropriate Linkage to Care

Linkage to care is incredibly important, and many individuals are lost to follow-up after obtaining their first dose of a vaccine that requires two or more doses or a booster shot (Stein & Nyamathi, 2010; Taylor et al., 2019). It is often difficult for individuals to remain engaged with care, and providing various forms for continued linkage or making systems changes to improve continued care is important. For instance, short-interval follow-ups between doses have been shown to improve vaccine uptake (Steele & O’Keefe, 2001). Mechanisms through data maintenance and respectful client tracking are essential to ensuring that individuals obtain subsequent doses of vaccine to complete their course. Strategies such as appropriate vaccination records with reminders, including automatic immunization reminders for clinics, can be key to ensuring vaccinations are addressed in clinical settings (Tung et al., 2003; Washington-Brown & Cirilo, 2020; Waterman et al., 1996)

Transiency, Incarceration, Drug Use, and Mental Health

The very experience of homelessness encompasses transiency, whereby individuals are often on the move from one jurisdiction to another, and they often move in and out of systems such as incarceration, housing, hospital, and other locations. As such, it may be difficult for them to engage with specific community-based services that are provided at a single location (Wood, 2012).

Addiction and mental health concerns also compound the inability to obtain a vaccine. Individuals with substance use concerns are often more occupied with managing their substance use to the point that they cannot commit to other health supports or vaccinations. Mental health concerns often cause distress and lead to decreased motivation for support. Specifically, depression and anxiety can be a barrier to further care, including vaccination (Wood, 2012). Where at all possible, vaccination campaigns should aim to support clients with other medical needs such as substance use management along with mental health to ensure vaccine uptake as well as improved follow-up. Integrated mental health, substance abuse, and medical services, when paired with vaccination supports, can improve vaccination uptake (Nyamathi et al., 2005).

Intentional Nonadherence

Distrust Surrounding the Health Care System

People experiencing homelessness (PEH) often have deep-seated mistrust for the health care system. This is born from stigma, trauma, and prior poor experiences from health care providers, as well as mental health issues fostering paranoia and avoidance (Doroshenko et al., 2012). Additional concerns voiced include distrust for clinicians as well as the lack of availability of key clinicians and family physicians (Vlahov et al., 2007). Misinformation around COVID-19 vaccines has further perpetuated mistrust in the medical system.

Mistrust often goes beyond the health care provision to research and government agencies, especially around the conduction of clinical trials, and fears of being “experimented on” if asked to participate in a clinical trial (Koniak-Griffin et al., 2007). This is often compounded into mistrust in the effectiveness and safety of the vaccine (Beers et al., 2019).

Mistrust of government is also apparent when it comes to disbursement of vaccine-related information. Nougairède et al. (2010) found that a top-down strategy for distributing vaccine management information by the government was found to be ineffective as a lack of trust in politicians exists. There seems to be a greater regard by the public to receive information from general practitioners directly rather than the top-down approach (Nougairède et al., 2010).


At times, an unwillingness to be vaccinated is more reflective of the perceived risk of coming in contact with an infection or having a poor outcome from infections. Certain PEH consider themselves at low risk of having poor outcomes from a communicable disease and would rather risk the consequences of the communicable disease as opposed to the vaccine (Beers et al., 2019; Bryant et al., 2006). This has been demonstrated in the past with diseases such as influenza but was more recently demonstrated with the COVID-19 pandemic (Kong et al., 2020; Metcalfe & Sexton, 2014).

Facilitators of Adherence

It is clear that many barriers hinder the willingness of people experiencing homelessness (PEHs) to become vaccinated. However, several factors that increase uptake of this intervention have also been identified. These range from correlational demographics to community support and access.

Several demographic factors correlate to increased vaccine uptake. Altice et al. (2005) found that older age, injecting daily, and being homeless were related to an increase in completion of a three-part vaccine course. A separate study found that African American ethnicity, positive coping skills, and having social supports, poorer health, no prison history, and a belief of greater self-efficacy correlated with completion of an HIV vaccine program (Stein & Nyamathi, 2010).

Older age, chronic homelessness, having a partner, belonging to a minority race, and not having access to routine medical care were also found to positively correlate with wanting a vaccine (Bryant et al., 2006; Nyamathi et al., 2012). These highlight the importance of providing vaccinations for this population as well as a need for a more targeted vaccine approach for PEH whose demographics do not fit within the correlates.

Increasing Access

PEH and individuals who inject drugs are at an increased risk of infections such as Hepatitis B, but they often do not have access to primary care to receive preventative vaccinations (Altice et al., 2005). Vaccine uptake is directly proportional to the number of access points available for clients to obtain vaccines (Vlahov et al., 2007). Increasing access points that provide vaccines in a flexible manner such as walk-in clinics can be helpful (Waterman et al., 1996).

Vaccine blitzes through outreach can be a helpful and structured way of providing vaccines (Kong et al., 2020; Schillberg et al., 2014). Vaccine blitzes targeting spaces that PEH frequent such as shelters, hotels, soup kitchens, community agencies, drop-in centers, medical clinics, libraries, city jails, parks, and street alleys should be considered (Weatherill et al., 2004). Other considerations include atypical sites, such as syringe exchange programs, and can also increase vaccine uptake (Altice et al., 2005). Syringe exchange programs in particular provide an opportunity to interact with and offer vaccines to people who inject drugs (Altice et al., 2005). Other nontraditional settings where vaccines can be considered include meal service sites, bottle depots, and transit lines. These blitzes can be facilitated by using mobile clinics, as well as mobile foot teams and vans, which can directly reach clients in these atypical locations (Gallardo et al., 2020; Wiersma et al., 2010). When services are not available, there should be continued provision of information on vaccines at these community sites (Beers et al., 2019). This information can be provided through advertisements of the time/location of free immunization sites using client-appropriate media (e.g., ads on buses, beverage containers, pamphlets in grocery stores, grocery bags, ads in shelters, messages via email). Additionally, in order to maintain trust, advertisements should be positive and not be threatening or moralizing (Doroshenko et al., 2012).

Any touch point in the health system can be a vaccine delivery point. This includes emergency departments (Cummings et al., 2006; James et al., 2009), pharmacies (Higginbotham & Pfalzgraf, 2012), and behavioral health centers (Duncan, 2018). Integration of vaccination screening and administration in routine health care should be especially considered for vulnerable populations who may not otherwise access resources (Doshani et al., 2019).

Improving Trust Within the Community

Relationship building with vulnerable populations including PEH is a key strategy in any health care endeavor (Wiersma et al., 2010). Vaccination campaigns when partnering with organizations or groups already familiar with the population tend to be much more effective in increasing vaccine uptake, especially when paired with structured community-based education campaigns (Vlahov et al., 2007). It is important to identify these familiar organizations, especially those with a well-established history of acceptance and utilization early, and work with them to custom tailor strategies for vaccination (Poulos et al., 2010; Tonner et al., 2013).

Education efforts around the vaccine should also be conducted by staff familiar to clients and occur in community-based areas where interaction with PEH is high (Syed et al., 2003). With large-scale public health campaigns, this can be done by leveraging staff who already work with PEH in clinics and shelters to provide education around the vaccination after educating them on key messaging points (Duncan, 2018).

Some evidence suggests that trust and education are incredibly effective. One qualitative study conducted in Canada found that PEH were willing to be immunized even if they had reservations about the efficacy or safety of the vaccines based on relationships built with health care providers (Doroshenko et al., 2012).

Trust through the use of people of lived experience or “peers” has been an important tool in vaccine acceptance. Individuals who have been through homelessness, substance use, and mental health concerns but are currently in a more stable place in life can be incredibly helpful to encourage and motivate clients to get vaccinated. The use of peer coaching and even nursing coaching has correlated to a high vaccination completion rate (Nyamathi et al., 2016). When this coaching is paired with motivational interviewing and targeted case management, results can be further improved (Nyamathi et al., 2005).

Trust can also be improved through culturally appropriate and competent care. The objective of this care is to increase understanding of vaccines but also improve self-autonomy and self-determination (Nyamathi et al., 2005). Increased health literacy through the lens of trust by provider counseling and peer-based educators can be incredibly helpful (Asgary et al., 2015).

Recommended Strategies

People experiencing homelessness (PEH) are at an increased risk of contracting many vaccine-preventable illnesses and have higher rates of chronic health conditions that predispose them to communicable diseases, but they tend to have lower vaccine uptake than the general population (Altice et al., 2005; Story et al., 2014). This is largely due to a lack of access to vaccines, distrust of the health care system, and a lack of public health programs that target PEH.

Several strategies have shown promise in increasing vaccine uptake. Developing access points and creating programs that directly target the needs of PEH are essential. Clinics and other outreach services should be set up in areas that PEH frequent to optimize access (Vlahov et al., 2007; Waterman et al., 1996). Vaccine blitzes and clinics at syringe exchange programs have both been shown to increase vaccine uptake (Altice et al., 2005; Weatherill et al., 2004). Additionally, any health care locations such as pharmacies or emergency departments can also be used as clinic sites to increase uptake (Cummings et al., 2006; Higginbotham & Pfalzgraf, 2012; James et al., 2009).

Providers, including physicians and nurses, are key to improving vaccination uptake through the provision of direct high-quality medical information (Nougairède et al., 2010). Providers should also be consistent in emphasizing the need for vaccines to all patients in a routine manner (Beers et al., 2019). For providers who do not routinely do this, provider education should be given to ensure best practices are conducted and maintained (Vlahov et al., 2007; Waterman et al., 1996). Additionally, determination of where large outbreaks can occur is important, and targeting high-risk populations at these locations would be most effective to curb transmission (Brouwer et al., 2020).

It should be noted that although many of our recommendations are outdated, they are still highly relevant. Indeed, the key principles outlined in the document apply to this day and were employed during the COVID-19 pandemic. For example, various vaccine delivery groups found similar trends in which a multipronged approach to providing the vaccines was needed. For instance, organized groups did outreach to locations where this population frequents, including shelters, specific encampments, and bottle depots. The key, as before, was to create as many touch points as possible to engage with this population. Coordination with various partner groups and the health authority was crucial. With encampments especially, coordination with city teams who monitor encampments to keep track of the population was done to ensure knowledge of where individuals were located but also if they had received the vaccine. While not available in every jurisdiction, vaccine incentives were considered especially in improving vaccine uptake.

Additional strategies and public health programs that specifically target PEH are necessary to increase the accessibility and uptake of vaccines in this population. These will ultimately decrease the rates of vaccine-communicable diseases and improve the health of the overall population.