Absorbing the shock: the role of lower-level health facilities in immunization resilience in Sidama, Ethiopia during COVID-19 pandemic

Although the COVID-19 pandemic disrupted routine immunization services globally, evidence from Ethiopia suggests limited overall impact. However, little is known about how immunization uptake varied across different facility levels and phases of the pandemic. This study examined these patterns in public hospitals, health centers, and health posts. We conducted a longitudinal comparative study of routine immunization service uptake across 18 hospitals, 132 health centers, and 532 health posts in Sidama Regional State, Ethiopia. To assess disruption and recovery patterns, we compared immunization uptake among infants under one year of age during the first 12 months of the pandemic (March 2020-February 2021) with the corresponding pre-pandemic period (March 2019-February 2020). We extracted data from the District Health Information System (DHIS2) and calculated percent changes with 95% confidence intervals. We compared mean differences in uptake using a paired t-test. Overall, immunization uptake increased by 9.72% (95% CI: 9.66%-9.79%) ( P = 0.006) during the first six months of the pandemic (March-August 2020), compared to the same pre-pandemic period. While hospitals experienced a decline of 5.2% ( P = 0.449), health centers and health posts experienced significant increases of 7.96% ( P = 0.015) and 11.5% ( P = 0.002), respectively. Compared to the six months immediately before the pandemic (September 2019 - February 2020), overall uptake increased by 3.90% ( P = 0.144), with a 14.01% decline in hospitals ( P = 0.151), and increases of 4.05% ( P = 0.275) and 5.45% ( P = 0.032) in health centers and health posts, respectively. During the post-lockdown period (September 2020 - February 2021), immunization uptake increased by 5.11% ( P = 0.007) compared to the same pre-pandemic period, including rises of 18.7% in hospitals ( P = 0.208), 2.5% in health centers ( P = 0.031) and 4.6% in health posts ( P = 0.004). Compared to the first half of the pandemic, hospital-level immunization uptake increased significantly by 38.15% ( p < 0.001). However, overall uptake increased only by 1.16% ( p = 0.461), while there were non-significant declines of -0.76% ( p = 0.627) in health posts and − 1.45% ( P = 0.790) in health centers. Over the full 12-month pandemic period, total uptake increased significantly by 7.35% ( p < 0.001) compared to the previous year. Health posts showed the largest gain (7.99%; p < 0.001), followed by health centers (5.2%; p = 0.003); and non-significant rise of hospitals (5.3%; p = 0.376). Uptake of all vaccine types increased annually, except for BCG, which showed a non-significant decline ( p = 0.889). Immunization services in the region remained resilient during the pandemic across all vaccine antigens, primarily due to the capacity of health posts and health centers to absorb increased demand following disruptions in hospitals. These findings underscore the importance of decentralized health systems in maintaining immunization services during pandemics. Strengthening linkages across facility levels and minimizing early hospital disruptions are essential to ensuring service continuity.