COVID-19, the disease caused by severe acute respiratory virus 2 (SARS-CoV-2), has demonstrated capabilities of rapid transmission across populations [1]. First reported in 2019, more than 2.4 million deaths and upward of 117 million cases have been attributed to the virus as of March 2021 worldwide [2]. There have been extensive challenges in responding to the COVID-19 pandemic due to a lack of knowledge of the natural history of the disease profiles it produces as well as rampant misinformation, skepticism and conspiracies related to the virus and its mitigation efforts [3, 4].

In November 2020, Switzerland had among the highest laboratory-confirmed COVID-19 cases per capita in the world [5]. Young people aged 20 to 29 in Switzerland had the highest infection rates across all age groups, posing a considerable threat to vulnerable populations [5]. Although younger people are less likely to experience serious negative health outcomes as a result of a COVID-19 infection, their tendency toward greater frequency of social interactions made them an essential group to consider in controlling the spread of the virus [6–10]. In December 2020, vaccine variants started to become available. As of March 2021, Switzerland had not completed vaccinations of the eldest and most at-risk groups of the population or published strategies to vaccinate the rest of the population, including young people [11]. Thus, it is urgent to better understand vaccine hesitancy among young adults as they are important disease vectors to address in order to mount an effective immunization campaign [12–15]. It remains unclear whether COVID-19 vaccination limits further transmission, however, it is understood to protect vulnerable populations. According to the Strategic Advisory Group of Experts (SAGE) on Immunization, vaccine hesitancy is a behavior influenced by a number of factors including issues of confidence (trust in vaccine provider), complacency (perceptions of need and/or value of a vaccine), and convenience (access) [16].

Switzerland has among the lowest levels of vaccine confidence internationally [17]. In Switzerland, vaccinations are not compulsory and a national vaccination registry does not exist [18, 19]. This strategy was designed to provide autonomy in local governance but has led to suboptimal vaccine coverage among the general population [18, 20]. Coverage between cantons is variable, for example, measles vaccination coverage is lower in German- (71.3%) than French-speaking (85.0%) cantons [21]. Similarly, individuals in French-speaking cantons report greater influenza vaccine coverage than those in German-speaking cantons across all age groups [22]. Vaccine hesitancy and refusal leads to under-immunization, reduction in potential for reaching herd immunity, and increases the risk of preventable illness and mortality. The success of mitigating outbreaks is dependent on the public’s willingness to engage with preventive public health programs including immunization.

Reasons for accepting or declining preventive measures in pandemic situations include uncertainties of the severity of a disease agent, perceptions that vaccines are rushed to market, among others [23–27]. Emerging work on COVID-19 vaccine acceptance demonstrates that these attitudes are highly variable worldwide. Among European populations, approximately 7 in 10 (73.9%) reported a willingness to get vaccinated against COVID-19 in early April 2020 [28]. Over time, vaccine acceptance has been reported to be as low as 53.7% in Italy and as high as 80% in Denmark according to more recent data [27, 29, 30]. Decreases in vaccine acceptance were observed in Europe throughout the pandemic which is thought to be associated with lower perceived confidence in vaccine safety and effectiveness among populations [29]. Public perceptions of vaccines in Switzerland are poorly understood; existing research suggests a great influence of local socio-cultural contexts as determinants of vaccination decisions which may be distinct by Swiss region [31, 32]. More recent public opinion polls and peer-reviewed literature from around the world have noted a decreased willingness. For example, among adults in the United Kingdom and United States, approximately half responded that they would likely get vaccinated; in Switzerland, only 16% had the same response [3, 33–35]. These attitudes are not fixed and may change as nations report on successes.

Young people form risk perceptions related to health issues, in part, based on their perceptions of susceptibility and seriousness of a particular disease as well as social patterning from respected peers’ behavior [36]. Higher participation in immunization programs may occur when individuals believe that effective protections exist and when they are directed or enabled to engage in such activities [37]. Young people may base personal vaccine uptake decisions on misinformed or shortsighted heuristics whereby they perceive the side-effects related to a vaccine to be more likely than the disease it may prevent [38, 39]. These perceptions are informed by their physical and social environment which includes mass public health information campaigns. Successful campaigns create enabling conditions to seek reliable information on prevention and other services to help mitigate a diseased state. For example, human papilloma virus (HPV) vaccination rates among adolescent young Swiss women aged 16 years were 51% if they attended schools with a vaccination program and 37% if their school did not have such a program [39]. In Switzerland, there have been limited public attempts to actively engage and educate young people about their role in combatting the COVID-19 pandemic. The most high profile appeal for limiting social contact among young people came from the WHO in March 2020 [40]. It is unclear if and how this message was disseminated or tailored to young people in Switzerland. In the absence of reliable information campaigns, young adults may turn to the internet as a primary source of information about COVID-19 where there is little information quality control [41]. Scientific journals, media outlets and other respected sources of information were not immune to baseless claims during this pandemic, including conspiracy theories related to COVID-19 vaccine development and trials [42–48]. Perceptions of this media landscape and their associations with vaccine uptake are currently unknown among young people living in Switzerland in the context of the COVID-19 pandemic.

Sociodemographic characteristics have been observed to influence behavior and shape differences in cultural norms around vaccine uptake. For example, women tend to be more averse to vaccine uptake than males [49, 50]. Existing literature suggests differences in immune responses between the sexes, however, sex is not considered in the design or dosing of recommended immunizations, which may lead to undocumented adverse effects disproportionately affecting females [51]. Women also report more influenza vaccination concerns in terms of its efficacy and safety, and report more adverse reactions to vaccines in general which may explain their relatively lower uptake than men and greater hesitancy to participate in immunization programs [49, 50]. Higher education has also been associated with increased uptake of vaccines over the life course [52]. Differences in national background have been observed in vaccine willingness in Switzerland; non-Swiss children have higher vaccine coverage levels than Swiss children [53]. Relatively greater household economic resources has also been observed to affect vaccination attitudes and behaviors although this has been a confounder in some studies [32, 54].

To optimize COVID-19 vaccine utility, it is essential that national health authorities have an evidence base to inform the (re)allocation of resources to key and strategic subpopulations and to develop strategies to combat deficiencies in health literacy related to the COVID-19 pandemic. These activities should include the development of mass communication campaigns related to vaccination and clarifications of prevalent misinformation.

The current prospective, community-based study took place in Switzerland’s largest city, Zurich, over the course of the first 6 months of the COVID-19 outbreak in Europe and collected data specific to young people’s perceptions of the COVID-19 virus and their opinions on a hypothetical vaccine compliance strategy implemented by the Swiss government. The study sought to characterize its respondents along sociodemographic factors and provide perspectives important to the development of an evidence base for Swiss-specific pandemic responses targeting young people.

We expect that H1: there will be significant associations between female sex and lower vaccine willingness, H2: significant associations between perceptions of a favorable government response and media coverage and vaccine willingness, and that H3: experience with COVID-19 will be significantly associated with agreement to a mandatory COVID-19 vaccine.

Sample characteristics are displayed in Table 1. Overall, 525 respondents completed the fourth z-proso COVID-19 supplement survey which included the questions on vaccination. However, respondents who reported being outside of Switzerland at the time that the survey was administered were excluded; hence the analytic sample of 499. Perceptions of Swiss authorities’ response, politicians’ views, and media coverage are presented in Figure 1.

In September 2020, before any COVID-19 vaccine was approved worldwide, almost half of young adults in Zurich were either undecided or unlikely to get vaccinated against COVID-19 and also would not agree with coercive vaccine mandates. This is generally consistent with recent Swiss general population surveys, which reported that COVID-19 vaccine willingness has eroded as the pandemic and social restrictions have been prolonged [34, 59]. These low rates of vaccine willingness among youth and young adults is concerning; their cooperation with mitigation efforts such as vaccinations are essential to combatting COVID-19 at a national level [5]. To date, no information campaigns have yet been tailored to or systematically deployed specifically to young people in Swiss settings that expound on their importance to COVID-19 eradication efforts and the collective interest in their participation in immunization programs.

Historically, vaccination rates in Switzerland have not always been high enough to protect the population (18). Arguably, parts of the population do not sufficiently endorse vaccines as an acceptable and effective strategy to prevent disease or mortality. Coercive immunization programs in certain countries have proven to be effective in reducing morbidity and mortality of vaccine preventable diseases, however, they are ethically fraught, and may lead to further resistance [60, 61]. Switzerland values plurality and policy diversity among its different cantons; this is reflected in the cantons’ different immunization programs and outcomes. Deficiencies in vaccine compliance among cantons have been attributed to differing priorities and practices of policy makers and attitudes of vaccine gate-keepers (e.g., nurses, general practitioners) and engagement in alternative health care and education pedagogies [32, 53, 62]. Swiss communities report an openness to public programs if their autonomous decision-making is respected [62–66].

The findings of the current study suggest that in Fall 2020, young women in Switzerland were less willing to get vaccinated against COVID-19, more undecided about vaccination, and unlikely to agree to a mandatory vaccine. These findings are consistent with existing research on sex differences in vaccine acceptance and uptake.

In final adjusted models, Sri Lankan maternal background was associated with greater vaccination willingness, lower vaccine undecidedness, and more agreement to mandated immunization than all other national groups in the sample. These findings only emerged when socioeconomic background, which is a considerable social determinant of health and health behaviors, was adjusted for. Sri Lanka has vaccine coverage approaching 99% for most vaccine-preventable diseases [67]; thus, young adults with a Sri Lankan background may have stronger cultural norms of participating in vaccination programs compared to young adults from other nationalities with comparable socioeconomic status [68].

Young adults in the current study in higher ISEI quartiles were more likely to report vaccine willingness and being decided about vaccination. In other studies, socioeconomic status has been a confounder to vaccine willingness, as it has been associated with greater likelihood of an acceptance of alternative medicines that are not based on a biomedical model of health [69]. Future studies should continue to untangle the mechanisms that drive these alternative attitudes in order to identify intervention points that optimize local public health strategy.

Finally, the current study provides concrete evidence that while the population of young adults in Switzerland does not necessarily have to agree with the extraordinary measures that the Swiss government took in order to perceive that the national response was effective. When presented with what young people perceive to be balanced views from politicians, decision makers, and media, young adults are more open to participating in immunization programs and become more open to paternalistic strategies to mitigate the spread of COVID-19. These findings provide an evidence base on which to build mass information campaigns dedicated to subpopulations of young adults that adequately inform and build resilience against misinformation that may otherwise dissuade them from immunization efforts. Furthermore, it identifies women, those with relatively lower educational achievement, and socioeconomically disadvantaged groups as priorities for immunization information campaigns. Any public health effort should tailor messaging that is relevant to the target group, contains clear guidelines, and is easily understandable to improve health literacy specific to COVID-19 or any other contagion. When information is too complex, it fails to lead to disambiguation, increases feelings of despair and panic, and further confuses an already stressed population [70].

The current study used a broad and diverse sample that is representative of young adults living in Zurich during the time of the COVID-19 pandemic. While it may not be representative of French- or Italian-speaking Switzerland, it provides a measure that may be standardized that informs willingness to participate in vaccination programs. The findings may be useful during times of epidemics but also generally inform the Swiss National Vaccination Strategy and related public health activities. The substantial attrition across survey waves is a limitation mitigated with the development and application of survey weights to reflect the original sample in all analyses; it may have been further mitigated with a longer data collection period. The original target sample was generally representative of first-graders in Zurich in 2004. In the current study, we used sampling weights that allowed us to generalize findings back to this original sample, which consisted of a balanced sample of males and females. The use of non-validated scales is a potential limitation, but also a necessity during times of novel stressors for which we may not have well-established scales. The current study identifies groups that may have strong vaccine-adherence practices based on their national background that should be leveraged to inform public health practice in Swiss settings—specifically, factors that sustain and maintain strong immunization compliance. Furthermore, we emphasize the importance of including sex-based considerations in vaccine messaging development and identify populations that may be at risk of future immunization deficiencies.

Overall, our findings suggest that approximately half of young people living in Switzerland’s largest city report being unlikely to participate in COVID-19 immunization programs. However, when young adults perceived information in their media landscape to be balanced and objective, they were more likely to report a willingness to get vaccinated and even participate in a health authority-mandated vaccination program. In order to create and sustain these attitudes, targeted public information campaigns relatable to young adults, delivered at an appropriate language level that are easy to understand are essential to creating enabling conditions for participation in improving immunization coverage efforts.