The study aimed to map and assess the spatial risk for hospitalization due to Community-Acquired Pneumonia in children less than 5 years of age and its association with vulnerable areas. The findings evidenced geo-spatial locations with higher risk for hospital admissions due to Community-Acquired Pneumonia in children, related to social vulnerability and inequity in these areas, as well as to the difficulty for Primary Health Care to monitor these children.
The central district comprises the oldest region and the commercial center of the city, with considerably less area than the other districts. The estimated population at the time of data collection was 105,246 inhabitants, with a concentrated population and many homeless people in the area (with a basic profile of begging, drug addiction and drunkenness) [29-31]. The predominant economic classes, according to the Brazilian Economic Classification Criteria (CCEB), were B2 and C1 . In the health network, no FHU was implemented - the population had only one PDHU, three PHUs and a specialized center .
The southern district also did not have an FHU at the time of data collection, the health network being composed of one PDHU and three PHUs . This district had an estimated population of 91,372 inhabitants, home to the largest irregular settlement (subnormal urban cluster) and the largest number of families belonging to economic classes D and E in the city, as well as the highest percentage of families without income [30-31,33].
There was also a large number of irregular settlements (subnormal urban clusters) in the western district, as well as a high density households; the estimated population was 162,440 inhabitants and economic classes C1 and B2 predominated [31,33]. However, it was the district that had the most complex health network in the city, consisting of one PDHU, six PHUs, a maternal and child health center, ten FHUs and a specialized clinic .
The spatial analysis also identified coldspots in the eastern district - the most prosperous region of the city, with the highest percentage of people belonging to economic classes A1, A2 and B1, as well as the lowest percentage of the population without income . In addition, there was an expansion of real estate speculation in the area, with a higher concentration of high-end residential condominiums . The district had an estimated population of 171,661 inhabitants, being the most populous, however, with a considerably larger geo-spatial area than the other districts, which gave it a low population density [29-31]. Regarding the health network, the district included one PDHU, five PHUs and one FHU .
In summary, the spatial analysis revealed a concentration of cases of children hospitalized due to CAP in the regions with greater social vulnerability (low income, poor housing conditions and homelessness), as well as a lower occurrence of cases in the most developed and economically privileged area of the city. Furthermore, it should be highlighted that the explanatory model developed revealed that child hospitalizations due to CAP were associated with the social vulnerability of the population living in the municipality.
Spatial studies developed by other authors have also shown concentrations of cases of childhood pneumonia in areas with lower socioeconomic status, in countries such as Australia , Korea , United States of America , England  and Africa . In addition, in the Philippines and England there was a concentration of severe cases of pneumonia in children living in areas further away from the regional referral hospital [35-36].
The socioeconomic level has been described as an important risk factor for morbidity and mortality due to pneumonia and other lower respiratory infections among children of developing countries [5,37]. In the present study, although satisfactory maternal age and parental education were observed among the children hospitalized for CAP, the majority belonged to families with per capita income (US$293.51) below the national (US$515.69), state (US$701.96) and municipal (US$644.14) for the period .
In the scientific literature, the effects of social inequities on the occurrence and severity of pneumonia have been discussed, especially among children under five years of age [2,6]. Differences in disease morbidity and mortality have been found among populations from different social strata, with severe pneumonia in young children being considered a reflection of poverty [2,6].
Brazil has marked socioeconomic and cultural differences among its different regions. Furthermore, within the same state or city there are also marked disparities, with children whose family socioeconomic pattern is compatible with highly developed regions and children in situations of poverty. Studies developed in São Paulo, considered the most prosperous state of the country, indicated the highest occurrence of pneumonia among children whose socioeconomic condition is similar to that of children living in the states of the northeastern region, among the poorest in Brazil [7-8].
The effect of socioeconomic status on child hospitalization for pneumonia is mediated by issues such as maternal age and education, as well as access to resources . However, it is possible that this effect is also mediated by other factors, since the evidence related to the impact of these variables on the severity of childhood pneumonia varies according to the context studied. In the present study, the age and education of the majority of the mothers was satisfactory, although the income was low; an effect of income on the outcome was also observed in the case-control study from which the data of this research are derived , regardless of parents’ education levels.
From the spatial analysis of the present study, the results confirmed that the distribution of pneumonia in the geo-spatial area was coincident with greater socially vulnerable areas and poverty. Accordingly, low-income populations occupy marginalized spaces, lacking access to resources and services [9,39], with this situation constituting a social vulnerability, which could possibly even overcome individual and family protective factors. For example, a family with a well-nourished child, whose parents have a good level of education, but live in an area of social vulnerability (such as subnormal urban clusters or favelas) due to low income, may have difficulty taking the child to the health service at the first signs of the disease, causing the evolution of a severe condition, which requires hospitalization.
As pneumonia affects mainly impoverished areas and favelas or those with high social vulnerability and poverty, the population at greatest risk has a limited potential for political mobilization. Furthermore, the disease is not easily transmitted across social boundaries, unlike other infectious diseases, which also pose a risk to more developed countries and wealthier areas. In this context, childhood pneumonia continues to be a socially contained and politically neglected disease .
Accordingly, the global mobilization for the control of childhood pneumonia is a key point, requiring a broader understanding of the dynamics between individual and collective factors. Interventions aimed at strengthening individual protection, for example, may have different impacts according to the situation and the social space to which the child belongs.
The results of a study that compared clinical research on the effectiveness of the pneumococcal vaccine in children from different countries illustrated this dynamic, with differences found in the protective effect of the intervention, according to the country’s level of development and differences also observed within the same country, according to the area of residence . The hypothesis suggested is that, in areas with adequate access to health services, children are diagnosed at the first signs of respiratory impairment and receive early treatment, decreasing the magnitude of the vaccine’s protective effect; whereas, in areas with problems of access to early diagnosis and treatment, the protective effect of the vaccine on the child population would have a greater impact. Furthermore, in addition to protection at the individual level, vaccination coverage of the exposed population contributes to collective protection, controlling the circulation of the etiological agent .
The non-governmental organization Save the Children advocates the development of action plans for pneumonia, integrated with development strategies for the health systems . The plans must involve the investigation of children in areas of higher risk, ensuring access to trained teams, equipped for the proper diagnosis and treatment of the disease and supported by an effective referral system .
The Brazilian health system is guided by the organization in Health Care Networks, with PHC being the main gateway, care coordinator and organizer of the actions and services available in the network, aiming to optimize access and the use of the existing resources . The relevance of integrating child monitoring services and effective referral and counter referral mechanisms should be noted , particularly in the first years of life, when vulnerabilities to morbidities are greater.
The case-control study from which the sample of this research was derived identified, through hierarchical analysis, that eight of the ten variables that composed the final model referred to actions developed at the PHC level, especially those related to the monitoring and vaccination of the child, prenatal care and family planning. Furthermore, the quality of the PHC itself, assessed from the perspective of the child’s caregiver, had an important protective effect on the hospitalization of young children due to CAP .
The results of the present study indicate that the majority of children hospitalized for CAP lived in territories served by traditional PHC Units, called unidades básicas de saúde - UBS in Brazil. These units offer appointment and walk-in care in the dentistry, clinical medical, pediatric, gynecology and obstetric areas, as well as vaccination and pharmaceutical assistance. However, in this care model there is no family and community focus, which are attributes of PHC and are provided by the Family Health Strategy (FHS) and CHAP. The monitoring of families over time, as well as the home and community approach, allows the social factors involved in the health-disease process to be identified and understood .
Ensuring access to health services is one of the priorities in a plan to control childhood pneumonia. However, it should be noted that the physical presence of the health unit in a given territory does not guarantee access, since it presupposes a bond, extended opening hours, active searches in the community, ease in scheduling appointments and meeting the spontaneous demand, in addition to absence of geographical and cultural barriers, among other aspects . A PHC model that seeks to overcome social inequalities must have a family and community orientation, in order to understand its territory and population and prevent them from becoming health inequities.
Considering that the morbidity and mortality due to preventable diseases and health inequities affect the universal rights of the child, it is understood that the results of this study strengthen the perspective of the performance of health services in the defense of children’s rights.
The study provides evidence of the critical areas in relation to community-acquired pneumonia in children and its association with situations of social vulnerability and poverty, which may contribute to the strengthening of the Health Care Network and support public policies to reduce child mortality, for the Sustainable Development Goals and Agenda 2030. For the future, new investigations could verify whether there were changes in the epidemiological reality identified in the study and whether, with the context of the COVID-19 pandemic, there was cross infection with community pneumonia and how severely this has occurred in children. It would also be opportune to follow these children with a view to observing recurrences and/or new episodes due to reinfection. Considering the recent changes in the political and epidemiological scenarios, it is understood that the replication of these analyses may provide support for the discussion of the impact of the social context on the different etiologies of severe respiratory diseases in childhood.
As a limitation, it is emphasized that this study was carried out in a complementary way to the multivariate analysis, performed in a previous study, in which the other factors involved in child hospitalization for CAP were evaluated, with the data being aggregated in this study. Another limitation is related to ecological fallacy, in which the association observed in the study, does not necessarily hold for the individual level. Another issue is the time, the data was collected seven years ago, however, the results are current and relevant for understanding the spatial dynamics of the Hospital Admissions due to CAP in Children in the geo-spatial area and for assessing whether the local policies and strategic actions have been addressed to modify the reality revealed in the study.
 The methodology to define the CCEB classes uses a sum of points attributed to the possession of items and the level of education of the head of the family, generating 7 categories, among which A1 represents the highest purchasing power and E represents the most disadvantaged.