The prevention of child mortality through immunization is one of the most cost-effective public interventions in use in resource-poor settings. The Expanded Program on Immunization (EPI) aims at delivering the primary immunization series to at least 90% of infants [1]. However, inadequate levels of immunization against childhood diseases remain a significant public health problem in resource-poor areas of the globe [2]. Nonetheless, the reasons for incomplete vaccination and non-uptake of immunization services are poorly understood.

In Mozambique, the EPI targets seven diseases, namely tuberculosis, poliomyelitis, diphtheria, pertussis, tetanus, hepatitis B and measles. The reported coverage of the basic EPI vaccines in Mozambique is 80%–95%, but these figures include incomplete and incorrect vaccinations [3, 4]. This may be one of the reasons why measles epidemics continue to occur in Mozambique despite of the reported 80% measles vaccination coverage [5]. Additionally, it has also been shown that immunization coverage in not uniform throughout the country, with rural areas presenting significantly lower coverage's [2] and, thus, contributing to the circulation of wild-type measles.

The effectiveness of immunization programs in resource-poor settings can be influenced by factors such as the coverage of the health network, the existence and quality of outreach services, the quality of the cold chain, the liaison of communities with health services, the existence of population movements, and several other factors that are related to the vaccines in use, to health services or to communities. The relative effect of each one of the above factors may significantly vary according to geographical areas [6]. In this context, the understanding of local hurdles for effective immunization programs is crucial to develop and implement appropriate solutions.

This study was carried out in a rural setting in southern Mozambique with the following aims: first, to determine the magnitude of incorrect vaccination figures reported amongst children less than two years old; second, to identify factors that adversely influenced vaccination completeness and contributed to missed opportunities for the immunization of children.

Seven hundred houses with children younger than two-year old were visited. In total, 668 children fulfilled the inclusion criteria. The mean age of the children was 13 months (range 2–24) and 333 (49.8%) were of the female gender. Only 32/668 mothers (4.7%) could not produce a RHC or had been not living in the area for the last nine months and were later excluded from the sample.

The survey showed that 348 mothers (52.0%) lived far away from the health facility. The average walking time to the nearest health facility was one hour (range 3 minutes – 4 hours). Those who needed transport, spent in average 18.0 Meticais (range 1.0 – 140.0; 1 USD = 18.0 Meticais) for a one way trip to the health facility. The majority (n = 538, 80.5%) of the mothers were born in the Magude district and only 29 (4.3%) had a migration history in the past two years. Among them, 17 had migrated to an area within the district, 11 to places outside the district but within Mozambique, and just one to a country outside of Mozambique.

Only 142 (21.2%) mothers had heard about the EPI as a specific program. The major sources of information for this knowledge were the health facility (n = 67, 47.1%), the radio (n = 44, 30.9%), community workers (n = 25, 17.6%) and family and friends (n = 14, 9.8%). Vaccination was considered to be important by 642 mothers (96.1%) while 606 mothers (90.7%) did not know any contra-indication for immunization. However, only 423 (63.3%) knew that the vaccination program should be finished at the age of nine months with the measles vaccine.

The RHC showed that 507 (75.8%) children had been born in a health facility while nine (1.3%) children had no information registered regarding their place of birth. Among the 152 mothers that had a home delivery, 43 (28.2%) had delivered alone without any type of help, 102 (67.1%) had help from family or neighbours, and five (3.2%) were assisted by a traditional birth attendant.

This study was conducted in a homogeneous rural community in southern Mozambique. The majority of the interviewed mothers were from low or medium social economical status and all of them had a low or no educational level [8]. Only children with a RHC were included in our survey. As these comprised more than 95% of the interviewed population, it is unlikely that our results are biased by excluding children with no RHC.

Our results show that mothers are motivated, understand the benefits of immunization and are willing to walk long distances to benefit from health care. In Mozambique, the average monthly salary is 540 MT (USD 33). Many of the mothers in the Magude District spent an average of USD 2.0 per trip to the health facility. Therefore, just the direct travelling costs for obtaining all the EPI vaccines are approximately USD 10.0 per child, the equivalent to 2.5% of the average annual salary. As the majority of the mothers were peasant farmers with no formal income, the money for the travelling costs came from other people in the family or alternative sources[8]. It was observed that in the administrative posts other than Magude Village, the risk of incomplete vaccination status was high. The reasons for this are probably linked with difficult access to the health facility since the population settlements were more dispersed.

Accessibility as a function of distance and need for using transport were identified as confounder variables for immunization non-uptake. However, spending longer than 60 minutes to reach the nearest health facility was demonstrated to have a strong negative influence in immunization uptake. Accessibility was seen to have no association with missed opportunities for vaccination which appeared to be linked to the quality of health facility services [9]. A friendly organisation of the health facility and a good coordination between fixed and outreach activities, including a strong involvement of the local community, could help to decrease the mothers' expenses on transportation and the time spent for obtaining vaccination services.

In spite of the fact that Magude district was considered a high migration area [8], our results show that only 4% of our population had a history of migration. Only four mothers referred to migration as a cause of non completion of their children's vaccination schedule. In a previous study in Mozambique [10], migrants were found to be less well vaccinated compared to long term residents in the area. In Cameroon, children of mothers with a history of migration were seen to be less vaccinated [11]. Migration might also be associated with low vaccine uptake due to the weak social integration of migrating populations. Nevertheless, factors such as the vaccination coverage in the settlement area and the mother's awareness of the importance of immunization may also play an important role.

There was no evidence to support that child gender had any impact on vaccine uptake or in defining missed opportunities for vaccination in our study area. In some societies with cultural discrimination against female children, boys have a greater chance to be vaccinated [12]. Marital status and age of the mothers were not seen to be associated with the use of immunization services. In other settings, both younger [13] and older age of mothers [12] has been reported to be associated with incomplete vaccination.

The low educational level of mothers has been previously associated with low vaccine uptake [13, 14]. In the present study, the no schooling status in mothers was strongly associated with low vaccine uptake. However, no association was identified between schooling of mothers and missed opportunities for vaccination. Mothers' educational levels had no influence on the child's vaccination status, probably because very few mothers had more than primary school education.

Health workers were seen to be a potential source for disseminating information relating to the immunization program in this community. This emphasised their position as role models in the rural community. The strengthening of communication, education and information skills of the health providers is an important step for improving health services in general. Regardless of the difficult accessibility to a health facility, the majority of the mothers had a delivery assisted by a health worker. Still, the high proportion of home deliveries (22.7%) represents a significant public health concern, specially considering the limited role of traditional birth attendants in this community. Moreover, home delivered children have a 2.27 times higher risk of not completing their vaccination program. Hence, the increase in the proportion of deliveries within health facilities will also lead to a better effective coverage of the EPI.

Previous studies in Mozambique [10, 15], have identified missed opportunities for vaccination and inappropriate use of contra indications as important factors inhibiting better EPI coverage.

In Magude District, we found that 28% of the children under two years of age were still in need of completing their vaccination program either due to incorrect vaccination or to missed opportunities. The high percentage of children without the BCG scar and vaccinated before nine months of age against measles is disturbing. Birth place outside Mozambique, change in immunization providers and living outside the Magude village were the factors that showed a stronger association with lower vaccination uptake.

Ninety one percent of the mothers did not know any contra indications for immunization. However 12% of 185 children had not been immunised at the health facility due to child illness. Minor illnesses in the family (fever, headache) had also been related with the non completeness of immunization program [16]. In this study, the mother's knowledge about any vaccine contraindication played a confounder role.

It has been reported in a review of 79 missed opportunity studies [9] that the quality of health services were an important cause of missed opportunities for vaccination. The large number of missed opportunities for vaccination in this community proved that the use of health services was high. Thus, exploiting visits for curative care would have been a cost-effective way of fully immunizing a child and increasing the EPI coverage. The all opportunities strategy is difficult to follow when the same health staff is part of both the fixed vaccination post and the mobile team. However, midwives and curative staff should be more involved in checking the vaccination cards and sending people to the immunization sessions. With scarce human resources and overwork, optimal co-ordination of different activities at fixed health stations and in mobile teams may almost be impossible without the strong involvement of the community.

The utilization of health services by the community in the Magude District is good. If the missed opportunities for vaccination and incorrect vaccinations were avoided, the vaccine coverage could easily reach national targets. Migration of the mother or their educational levels, did not influence in the vaccination uptake or contribute to missed opportunities for vaccination. The mothers were seen to be in favor of immunizing their children and were well informed about the immunization program, but they faced many barriers to complete their children's vaccination program. Special attention should be paid to mothers with home delivery as a BCG at birth is the gateway into the EPI.