People living in precarious conditions due to housing exclusion—whether homeless or in temporary shelters—have been disproportionately affected by the COVID-19 pandemic, with higher rates of illness and death, primarily due to factors related to their living conditions (such as lack of access to healthcare and overcrowding). Vaccinating these individuals against COVID-19 remains a significant challenge despite the efforts of numerous organizations on the ground and the introduction of the health pass in July 2021. In this context, the PREVAC study was launched among vulnerable populations, led by Epicentre, with contributions from Santé publique France.

COVID-19 Vaccination: Measures Implemented to Take Action

To better address the barriers to COVID-19 vaccination, Santé publique France established an initiative for mobilization and knowledge sharing involving researchers, field workers, and decision-makers: the Knowledge Mobilization Program (MobCo).
This initiative provided a structuring and mobilizing framework for partners, and led to a partnership with Epicentre/MSF for the design of the PREVAC study. This study made it possible to estimate these populations’ access to first-dose vaccination and to identify the factors associated with this first-dose vaccination.

Conducted among 3,800 people living on the streets, in squats or slums, in shelters, or in workers’ hostels, this study is the first of its kind in Europe. It provides real-world population data and highlights the need for a vaccination strategy targeted at these populations.

The Prévac Study: What Are the Findings and Lessons to Be Learned?

Access to vaccination varies significantly depending on housing type

The study was conducted in the Île-de-France region and in Marseille at 227 sites. Participants were interviewed in person at their place of residence (street, subway, encampment, squat or shantytown, shelter, national reception and emergency housing facilities, “115” hotels managed by Samu Social, workers’ hostels, or travel communities’ reception areas).

The results show that these individuals are less vaccinated than the general population, with a two-month delay in receiving their first dose. This vaccination rate varies significantly depending on the type of housing: in the Île-de-France region, first-dose vaccination rates were close to 80% in workers’ hostels, shelters, and social hotels. It was half as high—around 40%—among people living in permanent sites for travelers, slums, informal squats, and those living on the streets, whether in the Île-de-France region or in Marseille.

These results highlight the crucial role of housing as a structural determinant of health and show that the gradient of social integration and precariousness goes hand in hand with that of vaccination: the more excluded and marginalized a person is, the less likely they are to be vaccinated.

Two complementary vaccination strategies: “bringing people in” and “reaching out”

Another key finding concerns the necessity of both “Bringing In” and “Reaching Out” vaccination strategies for these populations. While vaccination was primarily (54.9%) carried out in vaccination centers open to everyone—highlighting the importance of standard public health systems—the use of more targeted “outreach” programs reached nearly 20% of individuals and tripled the likelihood of receiving the vaccine for people living on the streets, recent arrivals in France, and members of the traveling community. These results highlight the complementary nature of these approaches. Overall, trusted third parties—social workers and shelter providers—played a major role in disseminating information about vaccination.

Factors associated with access to the first dose of the vaccine

These factors were: being over 65 years of age, being French-speaking, holding or awaiting a valid residence permit, having health insurance, being under the care of a primary care physician, holding a positive personal opinion about vaccination or having a social circle supportive of the vaccine, obtaining information through one’s host, and avoiding the internet and the press.

Additionally, needing the health pass, eating meals provided by one’s host, having been hospitalized for COVID-19, and trusting the authorities to manage the crisis were also factors positively associated with first-dose vaccination.

Regarding the reasons for acceptance or refusal, nearly a quarter of participants cited the health pass as the determining factor in their decision to get vaccinated, while reasons for not getting vaccinated were primarily linked to vaccine refusal, driven by fears of side effects and a perception that the vaccine is ineffective.