The coronavirus disease-19 (COVID-19) occurred in China in December 2019 and spread worldwide, resulting in a global pandemic [1]. In South Korea, the first COVID-19 patient occurred in January 2020, and the fatality rate is so far about 1.62% [2]. Regarding the proportion of confirmed cases in South Korea by age, the proportion of COVID-19 among college students aged 20 to 29 years old is 14.95%, which is about twice as high as the figure of 6.92% among those aged 10 to 19 years old [2]. There is no specific treatment for COVID-19, and preventive behaviors such as hand washing, wearing a mask, and social distancing have been emphasized [3]. Since December 2020, several vaccines using mRNA or adenovirus vector have been developed and are being administered in many countries [4]. Vaccination and adherence to preventive behaviors are important ways to manage the COVID-19 pandemic [5].

Vaccines trigger the activation of the immune system against pathogenic microorganisms, thereby providing defense against concerned diseases [6]. Vaccines may cause adverse reactions other than disease prevention. Adverse reactions such as fever, muscle pain, and headache have been reported during the development of the COVID-19 vaccines, but fatal adverse reactions are not common [2]. Regardless of the efficacy of the vaccines, severe side effects associated with vaccination may lead to vaccination avoidance [7]. In the 2015 national survey on vaccination in Korea, most people were aware of the need for vaccination, but they were not 100% sure about the safety and efficacy of vaccines and have anxiety about associated side effects [8]. A previous study regarding H1N1 influenza virus vaccines found that higher perceived benefit of vaccination was associated with higher vaccination intention [9]. The major reason negative for COVID-19 vaccination was reported to be anxiety that the vaccines were developed too quickly and thus are not safe [10].

Considering the characteristics of college students in their 20s who have less fear of novel diseases compared to other age groups and live actively, vaccination is essential for them to maintain their health and prevent the spread of the infection to other members of society [11]. However, early adults, to which most college students belong, do not recognize the need for vaccination due to their concerns about potential unknown side effects of the vaccines and their development process. About 25% of US medical students hesitated to get the vaccine, citing concerns about serious vaccine side effects and lack of trust in the information received from public health professionals [12]. Loomba et al. reported socioeconomic status, age, political orientation, confidence in vaccines, and knowledge and information about COVID-19 as factors influencing intention to vaccinate against COVID-19 [13]. Therefore, this study investigated the association between COVID-19 knowledge, health protection behavior, the psychological antecedents of vaccination, and vaccination intention among Korean college students.

In this study, the mean score for COVID-19 knowledge was similar to a previous study in Iranian university students (23.75 points when converted out of 35 points) using different items [18] but was lower compared to Australian study (26.48 out of 35 points) using similar items [15]. Differences in information sources may be revealed as differences in retained information. More than 80% of the participants obtained information about COVID-19 through broadcasting and SNS in this study and the Iranian study [18]. However, 72% of the participants in the Australian study [15] obtained information from official government websites and major media outlets. Fast-changing and incomplete information, such as SNS information, may increase concerns about COVID-19 [19]. In particular, the total correct answer rate was only 65.6% in this study. Only the symptoms sub-domain showed an 80% correct answer rate. Since knowledge of the general characteristics and transmission of COVID-19 may be related to the need for vaccination and compliance with infection prevention practices, it is necessary to improve the knowledge level by disseminating accurate information about COVID-19 through various channels [18]. The mean score for health-protective behavior was different from previous studies, which was higher compared to the Australian study using similar items [15] but was lower compared to Iranian study by a different tool [18]. The health-protective behavior may differ depending on the severity of COVID-19 at the time of the surveys in each country. In South Korea, the number of confirmed cases at the time of the survey ranged between 500-600 and high-intensity social distancing was maintained due to the third outbreak. In Australia, COVID-19 cases were few and most were infected from abroad [15]. In Iran, there were more than 5,000 new confirmed and the number of confirmed cases was on a gradually increasing trend.

Among the psychological antecedents of vaccination, the mean score for confidence was lower compared to previous studies for university students in Dutch university [20] and for nurses in Hong Kong [21]. Confidence in vaccines refers to belief in the effectiveness and safety of vaccines [17]. Individuals that do not know exactly about vaccines may have negative attitudes toward vaccines along with low trust [17]. The lack of detailed explanations of the vaccine by governments and the medical community and the negative language by the media could influence public confidence in the vaccine [22]. Controversy over the efficacy according to types of COVID-19 vaccines was and concerns about serious side effects such as thrombosis with thrombocytopenia syndrome have also been raised [23]. As it is an important factor that can reduce trust in vaccination, it should be resolved by providing accurate information through various channels.

The mean scores for complacency, constraints, and calculation for vaccination was higher compared to Dutch university student study [19] but lower compared to Hong Kong nurses’ study [20]. Complacency refers to a feeling that the vaccine-preventable disease has low risk or thinking that a vaccine is not needed [17]. Wismans et al. [20] found that as descriptive norm for COVID-19 was higher, the level of complacency was lower and vaccination intention was higher. Meanwhile, the constraints of vaccination reflect barriers related to geographic accessibility, comprehension (language or health literacy), and economic status [17,20]. Travel time or inconvenient procedures for vaccination can also act as barriers [17]. This result is thought to be due to differences in access to medical institutions and in national economy or welfare levels among countries. In terms of GDP, the economy is in the order of South Korea, the Netherlands, and Hong Kong. However, the welfare in Netherlands ranks fourth among OECD countries [24]. To reduce the constraints of vaccination, it is a meaningful approach to enhance the national welfare policies for vaccination, such as vacations after vaccination and therapeutic compensation for side effects of vaccine. Calculation, as another psychological antecedent of vaccination, is related to perceived risk of infections and vaccination after individuals’ engagement in information searching [17]. Individuals’ negative perceptions of infection and vaccines can change their views about the risk, leading to the increase of calculation scores. The misinformation may be usually ignored, but it may increase individuals’ anxiety during a prolonged pandemic such as the current situation. Therefore, efforts to prevent an infodemic through false or misleading information can be important to increasing vaccination uptake.

The mean score for collective responsibility was lower compared to the Dutch university student study [20] but higher compared to Hong Kong nurses’ study [21]. Collective responsibility refers to willingness to protect others through own vaccination [17]. The Dutch university student study was conducted at the beginning of the pandemic, and Hong Kong was a successful country in the early stages of quarantine. Korea was at a time when the number of confirmed cases increased due to the third wave. In other words, the difference in the risk of exposure to COVID-19 at the time of the study may be related to collective responsibility. However, all the three studies revealed that the score for collective responsibility among the psychological antecedents of vaccination was the highest.

The results of the current study revealed that confidence, calculation, and collective responsibility among the psychological antecedents were the factors affecting vaccination intention. It was different from the results of previous studies [20,21] reporting that confidence, complacency, and collective responsibility were the factors affecting vaccination intention.

The confidence among significant factors is considered the most important in practice. Since COVID-19 vaccination is an individual’s voluntary choice and individuals are to be vaccinated with their consent, trust based on accurate information on the positive and adverse effects of the vaccination should be provided to ensure a high vaccination rate. Calculation is the deliberation for vaccination [17]. The results of consideration may vary depending on what information individual has and can be approached [7,18]. Therefore, it is necessary to continuously explain that vaccines are an effective strategy against COVID-19, adverse reactions of COVID-19 vaccines can be treated and safer than COVID-19 infection. This can be improved when the government, which determines the quarantine policy, communicates effectively with the people at various levels. In fact, European Union established an official website for countering false information to improve the quality of information and to strengthen the public’s media literacy [25]. The significance of collective responsibility on vaccination intention is consistent with those of a previous study [26] revealing that attitude toward vaccines was affected by civic responsibility for population health or the value of social solidarity. In addition, Wismans et al., [20] suggested that collective responsibility was directly related to altruism toward others. Therefore, vaccination campaigns with focus on the psychological characteristics of collective responsibility and the meaning and importance of herd immunity can be a strategy to inspire individual altruism and increase vaccination intention.

In this study, COVID-19 knowledge and health-protective behavior was found to not be significantly associated with COVID-19 vaccination intention. Loomba et al. [13] involving a randomized online population revealed that false information on COVID-19 lowered vaccination intention. A previous study regarding HPV vaccination [27] also reported that infection-preventive behavior was not significantly associated with HPV vaccination intention. However, scientific evidence-based knowledge is related to attitudes toward the vaccines and preventive behavior [28]. Therefore, efforts are needed to provide evidence-based accurate information and further studies on these topics are also needed.

This study identified factors affecting COVID-19 vaccination intention among college students in South Korea. The confidence in vaccination, calculation (personal consideration), and collective responsibility significantly influenced vaccination intention, all of which were factors affected by accurate information. Therefore, it is necessary for healthcare professionals and the government to provide accurate information about the COVID-19 vaccines and to implement public awareness programs regarding the positive effects of vaccination and misconceptions about the adverse effects of the vaccines.