Challenges in estimating vaccine coverage in refugee and displaced populations: Results from household surveys in Jordan and Lebanon

Ensuring the sustained immunization of displaced persons is a key objective in humanitarian emergencies. Typically, humanitarian actors measure coverage of single vaccines following an immunization campaign; few measure routine coverage of all vaccines. We undertook household surveys of Syrian refugees in Jordan and Lebanon, outside of camps, using a mix of random and respondent-driven sampling, to measure coverage of all vaccinations included in the host country’s vaccine schedule. We analyzed the results with a critical eye to data limitations and implications for similar studies. Among households with a child aged 12-23 months, 55.1% of respondents in Jordan and 46.6% in Lebanon were able to produce the child’s EPI card. Only 24.5% of Syrian refugee children in Jordan and 12.5% in Lebanon were fully immunized through routine vaccination services (having received from non-campaign sources: measles, polio 1-3, and DPT 1-3 in Jordan and Lebanon, and BCG in Jordan). Respondents in Jordan (33.5%) and Lebanon (40.1%) reported difficulties obtaining child vaccinations. Our estimated immunization rates were lower than expected and raise serious concerns about gaps in vaccine coverage among Syrian refugees. Although our estimates likely under-represent true coverage, given the additional benefit of campaigns (not captured in our surveys), there is a clear need to increase awareness, accessibility, and uptake of immunization services. Current methods to measure vaccine coverage in refugee and displaced populations have limitations. To better understand health needs in such groups, we need research on: validity of recall methods, links between campaigns and routine immunization programs, and improved sampling of hard-to-reach populations.