The overall immunization rates of the 2nd month immunizations were not significantly reduced under the impact of the SoE in Benguela Province, Angola. Although previous reports have described a reduced coverage of childhood immunizations during the pandemic in low- and middle-income countries, such trends were not found in our cohort [2, 4, 7, 8].
Our results might suggest the resilience of the childhood immunization program in Benguela Province in the face of epidemics. During the early phase of the pandemic, the Angolan government made a policy to maintain routine health care services [14]. In our study, missed immunizations due to a closure of health units were scarce. Continuation of routine health care services might have been helpful in preventing the disruption of childhood immunizations. Our results were in line with a report from Kenya, which described minimal impacts of the pandemic on the childhood immunization coverage [15]. In Kenya, multiple contingency measures were in place, including a separation of immunization services and COVID-19 centers, and a distribution of extra vaccines to provincial health offices before the pandemic [15, 16]. This implies the importance of preemptive contingency plans before the surge of cases to maintain the childhood immunization programs during epidemics.
However, we found decreasing immunization rates in the recommended months in rural municipalities. This might have been due to sociomedical factors, including limited access to health care services and health-related knowledge, and a reduced distribution of vaccines [17, 18]. In fact, unavailability of vaccines was the biggest reason for missed immunizations in our study. Immunization programs during public health crisis might benefit from first focusing on support for vulnerable areas (e.g., rural areas). In our study, the immunization rates in the recommended month, but the overall rates, were reduced in rural municipalities. This indicated that infants had access to catch-up immunizations. Our results suggested that enhanced catch-up immunization programs are warranted to mitigate the negative impacts of such public health crisis in those areas [19, 20].
The limitations of our study include a lack of information about the health-seeking behaviors and other immunization-related interventions, a short study period < 1 year, and the effects of the seasonality (e.g., rainy season) [21,22,23]. A longer period of observation might be useful in determining their associations. A potential sampling bias cannot be ruled out, as there might have been missing data in the immunization records of MCHHb. However, this was a small proportion and was not associated with any specific areas or months.
We used a dataset which includes both control and intervention groups of the RCT. Although it was assumed to have a minimal effect on our analysis, the immunization rates in the recommended months were higher in the intervention than the control groups (Supplementary Tables 1–2). This might suggest the impact of MCHHb on facilitating timely immunizations, as previous reported [24].
