Developing immunization providers is considered to be one of the strategies of manpower development of the National Vaccine Institute. Currently, there are more than 20,000 immunization providers. They are the main force in the vaccine drive to full vaccination and achieving higher vaccine coverage [1]. In Thailand, there is a systematic approach to human resource development, beginning with the orientation stage, in which the administration of vaccinations is introduced to new workers. In-service training is also provided, with the result that they constantly expand their knowledge base and review their various skills and principles [2, 3]. Worker supervision may be directed by an expert under the supervision of an Immunization network to develop their service [4]. At the same time, those engaged in the work can be refreshed in their academic knowledge through practical training based on the standard curriculum of immunization, which has been implemented each year from 2011 to 2019. Thus far, those who have completed their training number more than 3,000 [5]. Organizing the training according to the original format requires three days for each course, and there are various techniques for passing on the acquired knowledge, including lecturing, presentation of hypothetical roles, brainstorming, seminars, and demonstrations [6]. Each of these methods stimulates the interest of the provider, and the provider has accomplished an achievement after the completion of training and has accumulated some additional knowledge points [7, 8].

Nonetheless, practical training in the original format (face-to-face training) has a limitation in setting the number of meeting attendees at no more than 40 per graduating class, making it impossible to train all those involved in the work and the expenditure of a rather high budget [9]. As a means of reducing this gap in human resource development, the researchers decided on teaching technology in the form of online training that would enhance the ability of students or trainees to access a body of knowledge on a wide range of immunizations [10-12]. From a literature review [13], it was found that a few agencies in the country had used human resource development systems in their agencies through a diversity of online systems, such as the online training of the BMA Training and Development Institute, the online training system of the Department of Skill Development, the training management system of the Royal Irrigation Department, and the online self-learning system of the Department of Corrections. The purposes of using the online professional development system differ and may include the use of the online system to clarify the newly installed officers to create a basic understanding of the organization [10, 14]. Some projects, logging into the organization’s learning management system, have used it to set appointments; and the last of the groups used the online system to gauge the level of knowledge relevant to certain professional standards, such as a massive open online course (MOOCs) training in healthcare education, including nurses, medicine, and pharmacy [15]. It may be observed that most of the government-sector online systems in use for professional development are unidirectional in nature (for offline learning). These systems offer the advantage of granting students the flexibility of freely apportioning their study time. Students can thus manage their own time. Regarding these results, online course training in a developing country has emerged as an innovative educational tool in higher education and professional development. The potential contribution of E-course training for healthcare providers has become numerous in a few years during the COVID-19 pandemic [16, 17] or example, the online course in health promotion, community challenges, and public health education. It seems like an effective tool for scaling-up education. Due to the limitation of communication between the immunization providers and the Covid-19 vaccination course coordinator, they perceived their weak performance to access the training package. Hence, before launching an online training program, the developer should consider the demonstrated accessibility of online learning activities and the required baseline level of learners’ digital literacy [8, 18-20]. In this way, the use of online systems reduces the past limitations of the practical training format. Their use also promotes an increase in the number of workers who will be able to access the training. During this research, we applied the EPI e-course training version 1.0 in conjunction with the concept of quality cycle development, or the PDCA (plan, do, check, and act) of Deming [21]. It would be used to determine the procedure of concretely implementing the online training system and to monitor and evaluate the knowledge and skills of those who provide immunization services.

From the results of the study on the effectiveness of using the online immunization training system for healthcare providers, it was found that the providers who had received their training through the online EPI e-course training system had higher average knowledge scores than the group that had received ordinary supervision (p = 0.001). One explanation is that online learning or training assists in the expansion of knowledge by reviewing the body of knowledge through various activities, such as quizzes and playing games during the lessons in each content category. It helps the learner to review his knowledge in various subjects from time to time, as noted by AlMarzooqi et al. (2018), who stated that an online study often focuses on gauging knowledge and attitudes in the performance of work as important outcomes [25]. The use of the online learning system through virtual case studies about promoting the safety of patients aids the ability of the student to analyze a situation and to practice problem-solving according to the context [13, 25]. When testing the knowledge gained after studying, it has been found that medical students have higher average knowledge scores after their study than they had before their study, with a statistical significance of .01. They also have higher positive attitude scores on the prevention of mistakes in their practice with humans, with a statistical significance of .01 [26, 27]. Currently, the World Health Organization supports the use of the online training system for the development of a diversity of medical personnel, such as basic courses on evidence-based medicine e-course, vaccine safety, basic e-learning course, cervical cancer prevention e-learning course, and gender and humanitarian action. Not only does the online training system help to prepare basic knowledge in vaccine work for immunization providers, but is also capable of practical use for the expansion of knowledge in situations in which there is a spread of contagious-disease groups [20]. For instance, in a study conducted by Baggier et al. (2020), online training through an e-learning course for immunization service providers was found to be statistically significant in its effectiveness [28]. The course, which was centered on a campaign of measles and rubella prevention that occurred in Italy, aided the trainees in acquiring more knowledge than they had before their training. Trainees were also capable of correctly managing any outbreaks of measles or rubella they may encounter.

However, regular supervision can also contribute to their developing body of knowledge in their routine work since coaching as they work the practitioners to undergo constant improvement [29]. It was found from a literature review that the factors that influence immunization service skills depend on the nature of the work that has been assigned and a training experience that provides knowledge related to vaccine work, including supervisors characterized by their knowledge and skills in vaccine work [30]. However, from the nature of the health care services of the primary care units, it was found that the aspects of health reinforcement cover many areas of work, including the urgent mission of the campaign to build coverage for the anti-COVID vaccine. As a result, none of the practitioners will have every possible occasion to access the training system [31, 32]. Currently, various formats of training are being paired together with routine work to develop a body of knowledge that will comply with the standard criteria for immune system enhancement [33, 34]. In addition to the three-day workshops that comply with the curriculum of practice for immunization providers in Thailand [6], the work of immunization takes on other formats as well, including weekly two-hour vaccine knowledge reviews prior to service over a continual eight-week period (in-service training). The results of the study demonstrated, with statistical significance, that the knowledge test scores after training were higher than they were before training [35, 36], which is consistent with the results of this present study which used the online training system to develop the knowledge base of the practitioners. Moreover, it was found that the average knowledge test scores after learning with the EPI e-course training were higher than they were before learning in each of the content categories. The reason for these higher scores is that the training process in each content category entails a diversity of media formats that incentivize the student to review the content repeatedly [37, 38]. The online training system is even capable of displaying a self-learning progress bar for the student to view in each content category. The student is thus freely able to lay out a plan of learning. With each weekly evaluation, it has been found that test result scores after learning with the online training system continue to increase, matching the results of a study conducted by Brown et al. (2017), who studied the results of a program of immunization provider development in the nation of Nigeria by organizing two-day courses in academic rehabilitation training. Results of the research showed that the experimental group [39] that had undergone the training had knowledge test scores after their training that were higher than those of the control group. After gauging the results three months and six months after training, the healthcare providers still had average scores after their training that were higher than the group that had received only regular supervision. It can thus be seen that short-term training or training with the features of academic rehabilitation training can assist the development of a body of knowledge in vaccine work, but with an emphasis on basic vaccines that comply with the immunization plan of work [34, 40].

Currently, it has been found that new vaccines are being introduced into the plan of work for immunization services from time to time [41]. The aforementioned training program has thus been forced to modify its content completely, increasing the amount of content already embedded in the online system and causing long delays that have impeded learning through the online system [42]. A new format of learning was thus developed by integrating virtual reality technology into the training program for medical personnel. It was found from the results of our study that once we started the program that enabled the medical students to begin training on the online system and create their mock avatars, they were delighted. Members of the sample groups possessed both knowledge and understanding. After their training, they were able to offer some appropriate advice to the people on possibly getting new vaccines. There has been a statistically significant increase in the rate of coverage for anti-cervical cancer vaccines [43]. From the standpoint of systematically providing information pertaining to vaccines, it has been found that immunization providers who underwent the training were able to make practical use of the medical data in their decision of a correct choice of a vaccine. They were able to provide information to their service recipients. However, they were not able to respond to questions on complicated issues. For instance, there would be limitations in administering a vaccine in the case of a child who had contracted cancer [44]. Accordingly, while the online training program may take on various formats, it has already helped to develop a body of knowledge for immunization providers. In carrying out the work of immunization, online training should be provided alongside follow-up supervision of the immunization work at a primary level to develop a concrete operational standard over the long term for the future.

The results of this research indicate that the use of the online training system coupled with supervision in the work of immunization helps to increase the knowledge of immunization providers. Online training should be embedded as a basic method of personnel development, especially for those who work at the primary care level, which is the first line of service and important in driving the work of immunization for people.