The Prevalence, Features, Influencing Factors, and Solutions for COVID-19 Vaccine Misinformation: Systematic Review

"...provides comprehensive and up-to-date evidence on COVID-19 vaccine misinformation and helps responses to vaccine infodemic in future pandemics."

As a cost-effective measure to protect people against the COVID-19 pandemic, governments have implemented various policies to promote COVID-19 vaccination. However, as of early 2022, the global acceptance rate of the COVID-19 vaccine was only 67.8%. Misinformation around COVID-19 vaccines is a noteworthy component of contextual influences on vaccine acceptance or hesitancy. This systematic review aims to synthesise the global evidence on misinformation related to COVID-19 vaccines, including its prevalence, features, influencing factors, impacts, and solutions.

Guided by PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses), the researchers searched 5 peer-reviewed databases (PubMed, Embase, Web of Science, Scopus, and EBSCO). They included original articles that investigated misinformation related to COVID-19 vaccines and were published in English from January 1 2020 to August 18 2022. They used the Appraisal tool for Cross-Sectional Studies, version 2 of the Cochrane risk-of-bias tool for randomized trials (RoB 2), and Critical Appraisal Skills Programme Checklist to assess the study quality.

Of the 8,864 studies identified, 91 observational studies and 11 interventional studies met the inclusion criteria. The included articles were predominantly from American and European regions; there was less evidence from African, South-East Asian, and Western Pacific regions. Four types of study design were represented: survey-based study, internet-based study, interview, and experiment. The researchers divided vaccine-related misinformation into 7 types: conspiracy, concerns on vaccine safety and efficacy, no need for vaccines, morality, liberty, humour, and overstatement. They further divided these types into 54 different contents. Conspiracy and safety concerns were the most prevalent types of misinformation. Conspiracies were usually presented as half-truths, which made it hard to recognise them as misinformation.

Vaccine-related misinformation changed in its contents over time. The researchers compared misinformation among 3 phases, and found that, while some conspiracy theories and concerns on vaccine safety circulated in all 3 phases, the claims that vaccines were a hoax/fraud only appeared in phase 1.

Eight studies surveyed the sources of misinformation. Three studies reported social media as the main source; people who rely on print media and mainstream print were less apt to endorse COVID-19 misinformation. Two studies found that family and friends also played a role in COVID-19 misinformation.

There was a great variation in misinformation prevalence, noted among 2.5%-55.4% in the general population and 6.0%-96.7% in antivaccine/vaccine-hesitant groups from survey-based studies, and in 0.1%-41.3% on general online data and 0.5%-56% on antivaccine/vaccine hesitant data from internet-based studies. Younger age, lower education and economic status, right-wing and conservative ideology, and having psychological problems enhanced beliefs in misinformation. The content, format, and source of misinformation influenced its spread. One study showed that the change in misinformation was in close association with news or events related to vaccine developments.

Twenty-nine studies indicated that misinformation is related to vaccine hesitancy or negative vaccine perception, and 3 experimental studies also supported this finding. Besides vaccination behaviours, misinformation reduced the uptake of self-protection behaviours such as mask wearing, distancing, and compliance with health guidance. Sixty-five studies proposed solutions to address COVID-19 vaccine misinformation, and 9 studies assessed the effects of various interventions to combat misinformation. Table 4 summarises the proposed solutions according to a 5-step framework:

1. Identifying misinformation: routine fact-check and monitoring and investigation of misinformation
2. Regulating producers and distributors: policy and legal actions implemented by the government
3. Cutting production and distribution: technical, economic, and curatorial responses
4. Supporting priority audiences: empowerment of the public to improve health literacy and awareness
5. Disseminating trustworthy information: messages that directly debunk misinformation and that aim to transmit correct scientific information

Specific solutions in each study are detailed in Multimedia Appendix 6. Debunking messages/videos were found to be effective in several experimental studies.

In reflecting on the findings, the researchers note that social media is considered a "double-edged sword", in that the use of social media was positively associated with misperceptions regarding COVID-19 facts. However, because of its wide usage, social media can - and should, as argued here - be used to debunk misinformation and disseminate trustworthy information. The researches urge public health authorities and health professionals to shift their low-engagement status and be more actively engaged in COVID-19 vaccine conversation on online platforms. Social media platforms should also make rules and policies to combat misinformation.

In conclusion: "Combating misinformation is a persistent and complex work. More scientific evidence is needed to support misinformation surveillance, punishment of misinformation producers, and dissemination of trustworthy information....As many countries reported the first case of mpox, another epidemic in the shadow of the COVID-19 pandemic is looming....In this context, it is particularly important to synthesize potential intervention strategies to combat vaccine misinformation for future anti-infodemic campaign."