A health worker is a person who devotes themselves to the health sector and has the knowledge and skills from education in the health sector which, for certain roles, require(s) the authority to carry out health efforts. The health efforts of health workers can provide the example of the complete basic immunization status of their children to the wider population. The criteria for complete immunization in Indonesia followed the Ministry of Health Regulation No. 12 of 2017 concerning the administration of immunization: Every infant (aged 0–11 months) is required to receive complete basic immunization consisting of one dose of Hepatitis B, one dose of Bacillus Calmette–Guérin (BCG), three doses of diphtheria/pertussis/tetanus (DPT), hepatitis B (HB), Haemophilus influenza type B (HiB), four doses of polio drops, and one dose of measles-rubella (MR). ¹ Research suggests that health workers play a key role in maintaining and increasing immunization coverage. ^{2 , 3} However, a systematic review found that health workers who have good knowledge still have negative attitudes toward immunization, such as less belief in the benefits and safety of immunization, ^{3 , 4} so they are less likely to have their children receive immunizations and recommend them to the public. ^{3 – 7}

In 2019, in the East Java province, complete basic immunization coverage was at 95.5%. ⁷ Meanwhile, in the city of Surabaya, complete basic immunization coverage was 98.1%. The Universal Child Immunization (UCI) indicator shows villages or sub-districts that have received complete child immunizations. UCI data shows that in 2019, out of 8501 villages, 7686 (90.4%) had implemented village UCI, a figure that had risen from the previous year's 85.4%. ⁸ However, these figures are not comparable with the incidences of infectious diseases that can be prevented by immunization. In Indonesia, diphtheria is a re-emerging disease, especially in East Java. In 2019 alone, there were 358 cases of diphtheria in East Java. ⁸

Indonesian society is still influenced by community leaders, professionals, and/or environmental leaders who can serve as role models in certain matters and situations. Therefore, health workers as role models play a key role in increasing immunization coverage. Research has found that the determinants of immunization status are immunization goals, the readiness of health facilities, and community access. ⁹ Educational, economic, and health access factors play an important role in increasing immunization coverage, so much so that mothers who give birth in health facilities have a higher immunization awareness. ¹⁰ The community's motivation for immunization reflects the health workers’ motivation for immunization, including the respective risk factors and beliefs about immunization. ¹¹ Dr. Soetomo Academic Hospital in Surabaya is a referral hospital for eastern Indonesia with 1714 beds and 3332 health workers. Many studies show that people's motivation for immunization is the same as those of health workers. ¹¹ Health workers as role models play an important role in increasing immunization coverage. This study aims to determine the risk factors for incomplete immunization among the children of health workers at Dr. Soetomo Hospital.

A total of 148 questionnaires were distributed to participants who met the inclusion and exclusion criteria: 31 refused to fill out the questionnaire and two provided incomplete data, so a total of 115 participants were obtained. ²⁷ Of the 115 participants, 62 participants (53.9%) were included in the case group, which comprised health workers with incompletely immunized children, and 53 participants (46.1%) were included in the control group, which comprised health workers with completely immunized children ( Figure 1). The average age of the health worker participants was 31.8 years. The health workers were divided into two types: medical personnel (13.9%) and non-medical personnel (86.1%). The characteristics of the participants are presented in Table 1. Table 2 shows that the incomplete immunization of the children is 48.4% due to the COVID-19 pandemic, 29% due to illness, and 22.6% due to no time.

Table 3 shows the analysis of the bivariate test between several factors and the immunization status of the health workers’ children. Factors that had significant differences included parental age, parental knowledge, mother's education, and the presence of a pandemic with p-values of 0.043, 0.005, 0.002, and <0.001, respectively. Parental age had a 3.250 times greater risk of influencing incomplete child immunization. The older the parents, the greater risk for incomplete child immunization. For the mother's education factor, an OR of 3.221 was obtained, which means that the mother's low level of education had a 3.221 times greater risk of influencing incomplete child immunization. There were no significant differences between religion, occupation, father's education, parental income, birth order, history of the place of birth, and ethnicity in the immunization status of the children of health workers working at a tertiary referral hospital.

The results of the multivariate analysis on parental knowledge and income had a significant effect on the completeness of children's immunization, with a p-value of 0.017, 0.019; OR 4.887, 8.679; 95% CI 1.333–17.917, 1,429–52,701, respectively ( Table 4). Table 4 shows that low parental knowledge has a 4.8 times greater risk of influencing the incomplete immunization of children. In addition, parents with low incomes of around 1–3 million Indonesian Rupiah (IDR) (USD 67-201) have an eight times greater risk of incompletely immunizing their children. This suggests that the knowledge and income of parents may have an effect on the immunization status of the children of health workers at the tertiary referral hospital.

This study investigated the completeness of the immunization of children of health workers from the age of 0–to 24 months. To determine the immunization status of the children, the participants were required to have data records in their immunization books and/or cards. The knowledge of the participants in this study had a significant difference, with a p-value of 0.005 and an OR of 0.236, which means that the parents' knowledge has a 0.236 times greater risk of determining the incomplete immunization of children. In line with these results, research in Finland showed that the majority of Finnish health workers have high confidence in the benefits and safety of immunization and show confidence in other health professionals. However, low immunization confidence is found among a non-negligible proportion of health workers. ³ This study found that there were still health workers with low levels of knowledge, which led to the incomplete immunization status of their children. A systematic review stated that health workers who have good knowledge still have negative attitudes toward immunization: they have less belief in the benefits and safety of vaccination, so they are less likely to have their children receive immunizations and recommend it to the community. ^{3 , 5 , 13 , 14}

Our research found that 101 (87.8%) of the participants were mothers. A study in Eritrea, with a sample of 1323 mothers with children aged 0–59 months, found that the children of educated mothers had complete basic immunization compared to the children of mothers who were not educated. ¹⁵ Research in Georgia found that incomplete immunization is associated with a lack of maternal knowledge about immunization. ¹⁶ The findings of our study agree with those of Verulava et al.’s: maternal education plays an important role and is related to the completeness of the child's immunization ( p = 0.002). A study in China found that parental education is an important variable that influences parents' decisions on immunization. Parents with a bachelor's degree and above were more likely to immunize their children in the hope of effectiveness, but parents with a low level of education were less likely to have their children receive immunizations for this reason. Few highly educated parents refused immunization because of the risk of immunization, while less educated parents significantly declined immunization for that reason. ¹⁷

Parental age was also found to have a significant relationship with determining the immunization status of children. Previous research found that mothers and parents aged 20–39 years have doubts about immunization, especially in terms of its safety and effectiveness. ^{18 , 19} Meanwhile, according to Adokiya (2017), the increase in maternal age corresponds to an increase in the child's immunization status since mothers who are older have more knowledge of and exposure to previous immunizations than younger mothers. ²⁰ In Indonesia, women under the age of 16 are less likely to use health services than older women. Young mothers are often unable to make decisions on their own and tend to discuss decisions with family members. ¹⁰ In addition to parental age, the family income also has a significant influence on the immunization status of children. In Indonesia, based on law number 12 of 2017 concerning the administration of immunization, Article 30 states that the administration of complete basic immunization is provided free of charge according to a predetermined schedule. ¹ Although the implementation of immunization in Indonesia is free, incompletely immunized children are not uncommon. By providing complete immunizations, family welfare is one of the preventive health measures for children. ^{10 , 21}

This study found that many parents (41.9%) with incompletely immunized children stated that their reason for delaying immunization was due to the COVID-19 pandemic. The bivariate analysis of the difference between the COVID-19 pandemic incident factor and the immunization status of the children of health workers had a significant difference, with a p-value of <0.001. According to research by Olusanya et al. (2021), the background of the COVID-19 pandemic is an obstacle to vaccine non-compliance or rejection. ²² Immunization service providers facilitate standard health protocols that must be applied in immunization services. To combat the health issue during this pandemic, telemedicine video conferencing, outdoor/curbside/drive-through vaccine administration, minimization of the number of onsite patient visits at one time, and providing special, well-ventilated vaccine visits should be introduced to address the health crisis. ²³ The catch-up vaccine protocol issued by the Centers for Disease Control and Prevention to facilitate immunization coverage for children who missed their vaccine schedule during the pandemic should be implemented. ²⁴

Health workers have knowledge in the field of health, an important aspect to consider when investigating the attitudes of health workers towards immunization compared to the general population. Health workers are expected to have obtained evidence-based information about immunization. Such knowledge can also be obtained through experience gained both formally and informally. This knowledge includes the definition of immunization, immunization schedule, type of immunization, immunization goals, how to administer immunizations, and the effects of immunization. This knowledge shapes the health worker’s perception of whether or not their children should receive immunizations. Communities consider this knowledge to be the most crucial factor for locating immunization information. Low immunization confidence is found among a non-negligible proportion of health workers. ³

Although the participants in this study were health workers with the good, formal education necessary for a health worker, a low level of knowledge regarding immunization was still present, which indicates that the low level of knowledge factor would have a four times greater risk of influencing the incomplete immunization of the children of health workers at the tertiary referral hospital in Surabaya. In this study, family welfare was seen from parental income; low parental income signifies that the possibility of children being incompletely immunized is eight times higher than in the case of high parental income. This is supported by data on the characteristics of immunization facilities that are widely used by health workers, namely in hospitals, as many as 40%. The advantages of this research are that the data used were the immunization data records in the immunization books and/or cards of the participants’ children. A better source of data for tracking immunization status is medical records such as the Health Card or Maternal and Child Health books. ^{25 , 26} This study was conducted retrospectively; therefore, recall bias may have occurred, which is the limitation of our study. Recall bias may have occurred in regard to the parents’ reasons for the incomplete immunization of their children since all the data pertaining to that were based on the parents’ memory. However, this was unavoidable as we cannot track events that are not recorded objectively.

Low levels of parental knowledge and income are correlated with the immunization of the children of health workers at the tertiary referral hospital in Surabaya. More than half of the children of the health workers are incompletely immunized. This is a major concern, but many factors were not found to be related to the situation other than parental knowledge and income. However, another important factor that requires significant attention is the motivation of parents to get the best health-related quality of life for their children. People were reluctant to bring their children for immunization services due to the COVID-19 outbreak. Moreover, parental adherence to childhood immunization need to be investigated further to identify the parental motivations for providing the best quality of life for children. The role of the work environment also needs to be investigated further as it is related to the low level of knowledge of the participants with a complete immunization state.