Omicron scares and speculations are gaining momentum (1, 2). While much remains unknown about the new variant of concern (3), especially in light of the unknowns associated with the BA.2 lineage of the Omicron variant (4), as evidence continues to accumulate, it is becoming clearer that mass vaccination might be one of the best defense mechanisms society has against the outbreaks (5). However, vaccine fatigue may compromise people’s vaccination intention. It is important to note that the nonstop emphasis on the importance and imperative of COVID-19 vaccines has lasted as long as the pandemic has catapulted into a public health crisis (6). In an analysis of 7,000 publishers of content in English in 2021, researchers found that among the 275 million hours people spent on reading about the most discussed topics, stories about vaccines accounted for 43 million of the total hours, whereas an additional 27 million reading hours were spent on content related to various variants of the SARS-CoV-2 virus (7).

The emergence of Omicron in the Northern Hemisphere’s winter season further suggests that the diverse and dividing debates and discussions about COVID-19 vaccines could become even more intense, if not polarizing (8). Ranging from issues centering on vaccine efficacy, vaccine equity, to the need for booster shots, the accumulated burden and burnout that are resulted from various calls for action could further deepen people’s “vaccine fatigue” (9–11). To make situations worse, confusing and conflicting media reports about vaccination may further complicate the situation. Across the pandemic continuum, chaotic reporting or corrosive informatics on COVID-19 vaccines seen in a wide array of media platforms could often be described as unreliable, unfounded, distorted, to deadly 12–14). Take the United States Centers for Diseases Control and Prevention for instance. As of February 3, 2022, a time when booster shots are part of the vaccination regime, the agency still keeping people confused about what means to be “fully vaccinated” (14). The agency’s most updated (as of January 16, 2022) definition states that “fully vaccinated means a person has received their primary series of COVID-19 vaccines” (15), which is in direct contrast with the agency’s recommendations given by government and health officials like Dr. Anthony Fauci (16). This confusion, along with other competing directives and reports (17, 18), in turn, could increase the public’s skepticism about vaccination, and in turn, add avoidable stress to personal and public health (19), let alone their harms on pandemic control and prevention.

It is important to note that, though it has been poorly investigated, vaccine fatigue is not a new phenomenon (20). Vaccine fatigue could be particularly pronounced amid large infectious disease outbreaks, largely due to people’s pronounced needs to balance the burden and burnout associated with vaccination and “social conscience, solidarity, and feelings of duty” (21). However, due to a lack of research, little is known about what factors shape people’s vaccine fatigue. The importance of understanding the antecedents to vaccine fatigue is twofold. First, an in-depth understanding of the factors that cause or catalyze people’s vaccine fatigue can help government and health officials better address the issue. Overall, without knowing what factors influence people’s vaccine fatigue, it can be extremely difficult for stakeholders to develop evidence-based interventions to reduce vaccine fatigue’s impacts on mass vaccination. Furthermore, not having a comprehensive understanding of the phenomenon and developing countermeasures against it could cause vaccine fatigue to progress into more permanent forms of vaccination non-adoption, such as vaccine hesitancy or hostility (22). This, in turn, could further hinder society’s mass vaccination efforts. Thus, to bridge the research gaps, this study aims to examine the antecedents that cause or catalyze people’s vaccine fatigue, and highlight potential solutions that could help alleviate vaccine fatigue in society.

A literature review was conducted in PubMed, Scopus, and PsycINFO to identify factors that introduce or intensify vaccine fatigue in society. The preliminary search was conducted on December 2, 2021, with the final search completed on December 6, 2021. All scholarly papers that addressed “vaccine fatigue”, “vaccination fatigue”, or “immunization fatigue” were examined. Records were excluded if: (1) they were not published in English, (2) the vaccines studied were not for humans [e.g., for dogs (23, 24) and poultry (25, 26)], and (3) they did not provide full text for review. In terms of theoretical framework, the narrative literature review approach was adopted, which could be understood as “an objective, thorough summary and critical analysis of the relevant available research and non-research literature on the topic being studied” (27). One key advantage of the narrative literature review approach is that it can help the researchers gain a systematic and structural understanding of what could be scattered literature in an effective manner (27). A flowchart of the research process could be found in Figure 1.

Overall, among all of the 47 articles found via the targeted search, ten papers were excluded for not meeting the eligibility criteria. A total of 37 articles were included in the final review and analysis, which yielded 70 combined occurrences of the phrases “vaccine fatigue”, “vaccination fatigue”, and “immunization fatigue” (20–22, 28–61).

Except for two pre-prints (at the time of the review) (31, 57), all of the included papers are peer-reviewed. The terms were most frequently discussed in the context of infectious diseases in general (N=11; 29.7%), followed by measles, mumps, and rubella (N=6; 16.2%), COVID-19 (N=6; 16.2%), and polio (N=5; 13.5%). The phenomenon was mainly discussed in the context of pre-vaccination, with only five articles focusing on post-vaccine fatigue syndrome (N=5; 13.5%). Most of the studies utilized the term to refer to vaccine fatigue among the public, with only two articles discussed the phenomenon from the doctors’ perspectives (45, 51), and one included both parents and doctors’ points of view (38). As detailed in Table 1, a large number of articles only briefly mentioned the phrases, with limited to no insights into their antecedents offered (N=16; 43.2%).

This study set out to examine key factors that cause or catalyze people’s vaccine fatigue. This is the first research that systematically investigated the concept and phenomenon of vaccine fatigue. Vaccine fatigue could be understood as people’s inertia or inaction towards vaccine information or instruction due to perceived burden and burnout. By providing an in-depth and comprehensive understanding of the factors that form or fuel vaccine fatigue in society, the insights of the study can help government and health officials better design and develop countermeasures to limit the presence and prevalence of vaccine fatigue. Furthermore, our study could also help society prevent vaccine fatigue from progressing into worse forms of vaccine non-adoption (e.g., vaccine hostility), and in turn, contribute to the acceleration of mass vaccination in light of the Omicron scares and beyond. Overall, a wide range of antecedents to vaccine fatigue has been identified, ranging from the frequency of immunization demands, vaccine side effects, misconceptions about the severity of the diseases and the need for vaccination, to lack of trust in the government and the media.

Vaccine fatigue is detrimental to both personal and public health. Our study found that effective vaccine communications hold great promise in limiting vaccine fatigue among key stakeholders. The role of trust is also incremental to shaping people’s compliance with vaccine-related directives, which in turn, further emphasizes the importance of developing safer and more efficacious vaccines, along with responsible and accountable public health directives in mitigating vaccine fatigue. Overall, in light of the knowns and unknowns about COVID-19, ranging from the high transmissibility of Omicron to the lack of knowledge about Omicron’s variant—BA.2, in order to effectively prevent vaccine fatigue from plaguing pandemic control and prevention efforts, more endeavors are needed to understand the causes and consequences of vaccine fatigue amid COVID-19 and beyond.

ZS conceived the work, reviewed the literature, drafted, and edited the manuscript. AC, DM, CV, and Y-TX reviewed the literature and edited the manuscript. All authors contributed to the article and approved the submitted version.

This work was supported by FHS Faculty funding.

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

All claims expressed in this article are solely those of the authors and do not necessarily represent those of their affiliated organizations, or those of the publisher, the editors and the reviewers. Any product that may be evaluated in this article, or claim that may be made by its manufacturer, is not guaranteed or endorsed by the publisher.