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Despite gains in global coverageA proportion (%) that reflects the number of people receiving (an) intervention(s) divided by the total number of people eligible to receive of childhood vaccines, many children remain undervaccinated. Although mass vaccination campaigns are commonly conducted to reach these children their effectivenessThe ability of a campaign to achieve specific objectives related to coverage, equity, efficiency and impact. is unclear. The team evaluated the effectiveness of a mass vaccination campaign in reaching zero-dose children.
The team conducted a prospective study in 10 health centre catchment areas in Southern province, Zambia in November 2020. About 2 months before a national mass measles and rubella vaccination campaign conducted by the Ministry of Health, the team used aerial satellite maps to identify built structures.
These structures were visited and diphtheria-tetanus- pertussis (DTP) and measles zero-dose children were identified (children who had not received any DTP or measles-containing vaccines, respectively). After the campaign, households where measles zero-dose children were previously identified were targeted for mop-up vaccination and to assess if these children were vaccinated during the campaign. A Bayesian geospatial model was used to identify factors associated with zero-dose status and measles zero-dose children being reached during the campaign.
The team also produced fine-scale zero-dose prevalence maps and identified optimal locations for additional vaccination sites.
Before the vaccination campaign, 17.3% of children under 9 months were DTP zero-dose and 4.3% of children
9–60 months were measles zero-dose. Of the 461 measles zero-dose children identified before the vaccination campaign, 338 (73.3%) were vaccinated during the campaign and 118 (25.6%) were reached by a targeted mop-up activity. The presence of other children in the household, younger age, greater travel time to health facilities and living between health facility catchment areas were associated with zero-dose status. Mapping zero-dose prevalence revealed substantial heterogeneity within and between catchment areas. Several potential locations were identified for additional vaccination sites.
Fine-scale variation in zero-dose prevalence and the impact(i) The total, direct and indirect, effects of a programme, service or institution on a health status and overall health and socio‐economic of accessibility to healthcare facilities on vaccination coverage were identified. Geospatial modelling can aid targeted vaccination activities.