COVID-19 vaccine uptake and vaccine hesitancy in rural-to-urban migrant workers at the first round of COVID-19 vaccination in China

The coronavirus disease 2019 (COVID-19) is the largest and most challenging pandemic in the twenty-first century, causing a devastating threat to global health and economy [1, 2]. To date, more than 213 countries have come under the attack of the COVID-19 pandemic and more than 51 million individuals have been infected including at least 6.3 million deaths globally (WHO, 2022). In order to prevent the spread of COVID-19, Chinese governments have imposed various movement restrictions and lockdowns, including isolation, quarantine, school closures, travel restrictions, and cancellation of mass gatherings [3]. These interventions showed the effectiveness of controlling the COVID-19 pandemic, which might seriously affect social and economic development. In addition to movement restrictions and lockdown, vaccination that obtains herd immunity is a more fundamental way to control the epidemic. Therefore, the high coverage of COVID-19 vaccination is much crucial for controlling the COVID-19 pandemic [4‐6].

However, vaccination hesitancy is particularly evident in the initial period of the COVID-19 vaccine for marketing [7]. Vaccination hesitancy is a “delay” in acceptance or refusal of vaccination despite the availability of vaccine service (WHO, 2014), which is regarded as the top ten health concern by WHO [8]. The number of studies on vaccine hesitancy has increased rapidly since 2020 and most studies mainly focus on the nature of vaccination hesitancy [9], disparities [10, 11], as well as challenges and solutions on vaccine hesitancy [12, 13] among different high-risk groups including healthcare workers [9, 14, 15], pregnant women [16] and college students [17]. It is important to note that a range of determinants or predictors of vaccine hesitancy has been identified from individual differences [18], social environmental factors [19], and vaccine factors [20]. These studies highly indicate that vaccination hesitancy is a critical barrier to achieving the recommended COVID-19 vaccine coverage in non-mobile population. However, how is the prevalence and predictors of vaccination hesitancy in mobile population remains unclear.

First, we have chosen Chinese rural-to-urban migrant workers as our subjects. Rural-to-urban migrant workers, who migrate from rural areas of their original residence to urban areas for work-seeking, are a unique mobile group appearing in developing countries when experiencing economic transformation [21]. According to the National Bureau of Statistics of China, there were 290 million rural-to-urban migrant workers in 2020, making up more than one-third of the entire workforce in China [22]. Since the beginning of 2020, the end of the COVID-19 lockdown in China, massive migrant workers have poured into cities from place to place with constant changes in job or living conditions. The high mobility of migrant workers makes it difficult to monitor COVID-19 vaccination among this group and even leads to an increased risk of COVID-19 transmission if COVID-19 carriers exist. Moreover, COVID-19 vaccination hesitancy was associated with lower education levels, lower income, and health literacy [23], which are the most remarkable characteristics of migrant workers in China. However, a study on migrants in Shanghai, China reported a high acceptance of COVID-19 vaccination, no matter their socio-demographic characteristics [24]. Whether the cultural or regional differences contribute to such discrepancy in the association between vaccination hesitancy and individual factors remains unclear. Therefore, migrant workers may be a high-risk but neglected group of increased hesitancy for COVID-19 vaccination that deserves to be further investigated.

Second, we have chosen the first round of COVID-19 vaccination as the time of the investigation. The first COVID-19 vaccination campaign (referred to, in this paper, as the “first round”) was conducted from December 2020 to March 2021 when the COVID-19 vaccine was first approved for marketing in a few countries such as the UK, U.S, and China. It is a time not only under the urgent situation of COVID-19 prevention and control but under the uncertain situation of COVID-19 vaccine safety and effectiveness. As of December 13, 2022, the latest data showed that the COVID-19 vaccination coverage was 92.7% in China, and 90.4% had been fully vaccinated [25]. In first round of COVID-19 vaccination, however, a national survey showed that only 67.1% reported willingness and 35.5% were hesitant to accept vaccination [26]. The vaccine coverage was 34.4% in January 2021, which is far from the requirements of herd immunity [26]. Therefore, exploring the COVID-19 vaccination hesitancy of rural-to-urban migrant workers at this time is quite necessary and meaningful, which can generate more timely intervention on vaccination promotion for future epidemic events.

Finally, we would further attempt to understand and categorize the risk and protective factors of vaccination hesitancy based on the WHO’s Vaccine Hesitancy Determinants Matrix (VHDM) conceptual frameworks. VHDM model grouped the factors of vaccine hesitancy into four categories: individual factors, group factors, epidemic factors, and vaccine factors. Specifically, individual factors include personal characteristics (i.e., medical knowledge, preventive measures); the group factors include peer characteristics (i.e., friends support, family support); epidemic factors include epidemic characteristics (i.e., fatality, infection); vaccine factors include vaccine characteristics (i.e., vaccine necessity, safety, efficacy, importance, and vaccine reliability). For example, personal characteristics, including male, being married and healthy lifestyle were found to be associated with vaccine acceptance in China [27, 28]. Another study from China found that vaccine factors (i.e. trust in vaccine safety, effectiveness, access and price) appears to play a role in vaccine hesitancy [29]. To date, much of the existing literature on vaccine hesitance focuses on one of the above categories, whereas there is a lack of systematization and wholeness in research on it. VHDM model was drawn on adaptations of ecological models of health behavior to identify the multiple and interrelated levels of influence impacting vaccine hesitancy (Sturm 2005; Callréus 2010; WHO 2013; Larson 2014). Thus, it is theoretically and practically important to explore the factors of vaccine hesitancy based on the VHDM model to offer specific recommendations to translate COVID-19 vaccine hesitancy into acceptance and uptake.

To address the above research gaps, we: (1) investigate the coverage of COVID-19 vaccination in a large sample of 14,917 rural-to-urban migrant workers; (2) explore vaccination hesitancy in rural-to-urban migrant workers in the first round of COVID-19 vaccination; and (3) identify the determinants of vaccination hesitancy among migrant workers based on VHDM model.

This is the first study to explore COVID-19 vaccine hesitancy among the largest mobile population in the world at the first round of COVID-19 vaccination. In this study, the prevalence and characteristics of COVID-19 vaccine uptake and vaccine hesitancy were estimated, then vaccine hesitancy-associated factors were identified at four levels based on the model of VHDM.

The first startling finding was that COVID-19 vaccine uptake among rural-to-urban migrant workers at the first round of COVID-19 vaccination was extremely low and only 7.1%, which was much lower than the estimated coverage required to achieve herd immunity (70.0% or above) and even the national level in China during the same period (34.4%—42%) [26, 31]. This finding suggested that the implementation of the COVID-19 immunization program had been inefficient among rural-to-urban migrant workers. Therefore, more specific and robust policies and regulations are needed to enhance COVID-19 immunization in urban areas where the migrant workers mostly flowinto. Importantly, COVID-19 vaccine uptake among rural-to-urban migrant workers was positively associated with middle age, marriage, low education level, more medical knowledge, and past vaccination by choice experience. These factors have often been reported in previous studies [18, 20]. Therefore, more attention should be paid to young or unmarried adults with highly educated, medical knowledge or without past vaccination experience for COVID-19 vaccination.

The second finding highlights the alarmingly high rate of COVID-19 vaccine hesitancy in rural-to-urban migrant workers after the vaccine was made available was reported up to 62.1%. After COVID-19 vaccines are on the market, there was a surge of interest in estimating the rate of COVID-19 vaccine hesitancy around the world [32]. A Systematic Review [33] including 31 studies on COVID-19 vaccine hesitancy in 33 different countries showed that the lowest COVID-19 vaccine hesitancy rates were found in Ecuador (3.0%), Malaysia (5.7%), Indonesia (6.7%) and China (9.7%). However, the highest COVID-19 vaccine hesitancy rates were found in Kuwait (76.4%), Jordan (71.6%), Italy (46.3), Russia (45.1%), Poland (43.7%), the US (43.1%), and France (41.1%). Our findings were unique in revealing the COVID-19 vaccine hesitancy in the population of migrant workers and its relatively higher rate compared with the world average. However, it remains unknown whether the high hesitancy of the COVID-19 vaccine among migrant workers in China results from geographical differences or this particular sub-population due to the lack of comparable data. Therefore, it is necessary to obtain more data for further validation in future studies.

The third important finding of the study is that four levels of determinants were significantly associated with COVID-19 vaccine hesitancy based on the model of VHDM including individual, group, COVID-19 pandemic, and vaccine factors.

From the individual perspective of the VHDM model, gender, annual income, and medical knowledge at the first round of COVID-19 vaccination were three of the strongest factors associated with COVID-19 vaccine hesitancy among rural-to-urban migrant workers. Specifically, our findings were in concordance with the literature [34], where females showed more unwillingness to accept the COVID-19 vaccine than males. A previous systematic review on the global influenza pandemic in 2009 also demonstrated that females were less likely to be vaccinated than males [35]. The reason for this may be that men engage in riskier behaviors than women [36] and women tend to collect medical information from various sources when it comes to their families' health [36]. Furthermore, women’s hesitancy to accept the COVID-19 vaccine may make vaccinating children difficult, as women play a key role in child vaccination when the COVID-19 vaccine is accessible to children [37]. Secondly, income level was also associated with vaccine hesitancy where those with higher income migrant workers were more likely to be vaccine hesitancy. In this regard, the available literature also cannot provide a consistent result [38]. This discrepancy could be related to various standard incomes used, different samples selected, and different data analyses performed in these studies. Finally, medical knowledge was a strong protective factor of vaccine acceptance. Since vaccination could be considered one of the most important preventive measures to protect against COVID-19 infection, people with more medical knowledge and high awareness of prevention would likely be more willing to get vaccinated.

From the group perspective of the VHDM model, supports from family, friend and public opinion would be significantly helpful to reduce vaccine hesitancy. These findings were consistent with previous studies [39‐41] and support the views of the social-ecological theory that personal, family and social factors have a synergistic effect on individual's mental states and behavior [42]. Furthermore, vaccine hesitancy was a dynamic and potentially reversible state compared to avoidance or refusal and social support for vaccination is an important motivator for vaccine-hesitant individuals. As China is deeply influenced by collectivism, families, and friends have a profound influence on individuals’ emotions, behavior, and decision-making. Their guidance is a powerful component in the decision-making process. It should be noted that support from friends appears to be more important than from families, which is not consistent with the previous study on the general sample [39]. A possible explanation is that rural-to-urban migrant workers have to leave their families to work resulting in fewer connections with their families and weakening their families’ influence on their intention on COVID-19 vaccination. Thus, those with a low level of friend support were more likely to be vaccine hesitancy and vaccine refusal. Furthermore, respondents in the lower public opinion supportive environment are more likely to respond “no” versus “yes” to vaccine intention. It is clear that support from public opinion could increase the likelihood of stable trust in vaccine safety and effectiveness. As such, our study confirmed that a supportive environment seems to have a significant effect on the hesitant respondents.

From the COVID-19 epidemic perspective of the VHDM model, individuals who perceived the risk of the COVID-19 pandemic including high fatality, high infection, and emotional distress had a stronger intention to have the COVID-19 vaccine. This finding is consistent with a number of studies identifying the association between perceived COVID-19 infection risk and vaccine uptake and acceptance [43, 44]. Furthermore, our findings also confirmed the risk as feeling theory [45, 46], which maintains that people’s reactions to danger vary depending on the specific characteristic of a hazard. Specifically, if risks are perceived as more dangerous when they are uncommon and unknown to science, people would react in a positive and proactive way and vice versa. Therefore, the COVID-19 epidemic is likely to induce a high-risk perception as it is a new disease, for which both science and people have little or no information and experience, with a catastrophic nature, thus evoking strong feelings, which leads to an increase in the vaccine acceptance [47]. Meanwhile, those results confirmed the role of risk perception on judgment and decision-making in health care for a disease associated with serious consequences, uncertain outcomes, and limited scientific knowledge, showing how the perceived risk drives the decision to immunize.

From the COVID-19 vaccine perspective of the VHDM model, there is a strong positive association between all vaccine-specific factors and the intention to be vaccinated against COVID-19. Among them, vaccine safety and vaccine importance were the strongest factors associated with vaccine acceptance. Our result indicated that higher safety, effectiveness, necessity, and importance of vaccines will be critical to achieving high vaccine uptake among target populations especially in the early phases after the vaccine is on the market. Thus, public health initiatives should focus on increasing trust in vaccine safety and emphasize the importance of vaccines for individuals and society.

Our findings also indicate three implications. First, it is crucial for government and health authorities to formulate effective and appropriate vaccine policies and plans based on occupation, age, life characteristics, and VHDM. For example, the mandatory and accessibility of vaccination should be strengthened for high-risk occupational groups. Moreover, healthcare providers should disseminate transparent and accurate information about vaccines’ safety and efficacy to gain the trust of the population, especially those with vaccine hesitancy or refusal. As medical knowledge, and vaccine information were associated with vaccine acceptance, it is critical to make full use of multiple media to enhance the comprehensibility of vaccine information and to publicize vaccine safety, effectiveness, and importance. Finally, from the perspective of individuals, family and friend support contributed significantly to vaccination intentions.

The current study presents several strengths and limitations. A major strength is that we investigated the coverage of COVID-19 vaccination in a large sample of 14,917 rural-to-urban migrant workers, who might be particularly at risk in the COVID-19 pandemic. Furthermore, we explored vaccination hesitancy in rural-to-urban migrant workers in the first round of COVID-19 vaccination, a critical period of vaccination full of uncertainty. The current study was conducted in Wenzhou city of Zhejiang province, which allows for regional comparisons of migrant workers' vaccine hesitancy. Compared to another survey conducted in Shanghai, China [24], the rate of COVID-19 vaccine hesitancy was quite high (62.1%) in the current study. Moreover, our study identified the determinants of vaccination hesitancy among migrant workers based on VHDM model. While much research focused on one category of determinants, our study comprehensively measured individual, group, epidemic, and vaccine factors, which provided a systematic understanding on the associated factors of vaccine hesitancy.

We should acknowledge some limitations in our study. First, this study was based on a cross-sectional design, which was not possible to get a valid cause-and-effect relation between COVID-19 vaccine hesitancy and the associated factors. Secondly, the questionnaires were published via WeChat and the data about vaccination uptake were collected by using participants’ own reports, instead of through healthcare facilities. This may result in information bias. We will make effort to collect data through more reliable facilities to confirm the reliability of vaccine uptake. Thirdly, most of the respondents were from Wenzhou, Zhejiang Province, which may lead to a selection bias. Finally, not all components in the model of VHDM were included, such as culture, political circumstance, race, etc.

This study provides empirical evidence for the prevalence of COVID-19 vaccine intake and hesitancy in rural–urban migrant workers from the perspective of the VHDM model. Alarmingly, only 7.1% of migrant workers have been vaccinated against COVID-19, and up to 62.1% reported experiencing vaccine hesitancy. In conclusion, the uptake rate of the COVID-19 vaccine and vaccination intention was suboptimal to achieve herd immunity. It is urgent for governments, public health officials, and economic and social groups to develop a strategy to improve vaccination acceptance, especially in the working population. In this case, the VHDM model may serve as an effective tool for identifying determinants of vaccine hesitancy.