COVID-19 vaccination uptake in people experiencing homelessness during the first three years of the global COVID-19 vaccination effort: A systematic review and meta-analysis

There are complex barriers to vaccination, including COVID-19 vaccination, in people experiencing homelessness. Consequently, it is likely COVID-19 vaccination uptake in this vulnerable population is lower than in general populations. This systematic review and meta-analysis reports COVID-19 vaccination uptake in people experiencing homelessness, including in comparison to general populations, in literature published during the first three years of the global COVID-19 vaccination effort.

Searches were conducted on eight electronic databases. Peer-reviewed studies from high-income countries available in English and in full-text were considered for inclusion. Studies were considered up to 31 December 2023.

In total 1884 studies were retrieved and, after removal of duplicates, 1167 were screened. Thirty-one studies were included in this review. For studies reporting uptake of either any, or first, COVID-19 vaccine a random effects meta-analysis was used to pool coverage estimates. It included 28 first vaccine dose coverage estimates from 18 studies including 104,139 vaccinated individuals in 308,253 participants. The pooled estimate for first dose vaccine coverage in people experiencing homelessness was 43 % (95 % CI: 35 %, 51 %). The 95 % prediction interval was (0, 88 %). Uptake of subsequent doses was heterogeneous and was reported narratively. Uptake of the second dose ranged upwards from 31.3 %, and uptake of the third dose was reported in one study as 7.2 %.

COVID-19 vaccination uptake in people experiencing homelessness is lower than in general populations. Disparities in uptake persisted when comparing uptake at regional/state/national levels, at multiple timepoints, and in studies focused on different sub-populations including veterans. This is problematic, considering people experiencing homelessness are more likely to have poorer COVID-19-associated outcomes. It is important to recognise people experiencing homelessness are an at-risk, hard-to-reach group for vaccination, and vaccination strategies should be targeted to this population to improve uptake.