Could information about herd immunity help us achieve herd immunity? Evidence from a population representative survey experiment

Constructing vaccination slogans in the late stage of vaccine launch: an experimental study based on the framing effect theory

BACKGROUND

Vaccination is an important strategy for overcoming public health crises. Considerable studies have analyzed strategies to promote people's willingness to vaccinate, but few have explored effective strategies based on the stage of vaccine launch. This study considered the framing effect theory to explore whether egoism, altruism and loss frames can boost vaccination willingness when people feel the vaccine is effective in the late stage of vaccine launch.

METHODS

This study designed a scenario experiment consisting of three experimental groups (egoism, altruism and loss frames) and one control group (non-framed). Participants (N = 1085) from China were randomly assigned to any of the four groups. Vaccination willingness, perceived vaccine effectiveness and control variables included perceived susceptibility, perceived severity, worry about the side effects of vaccination and socio-demographics were collected.

RESULTS

Perceived vaccine effectiveness and message frames can increase people's willingness to be vaccinated. Message frames can amplify the positive impact of perceived effectiveness on vaccination willingness. Moreover, loss-framed messages had a stronger amplification effect than egoistic- and altruistic-framed messages.

CONCLUSIONS

Governments and other health authorities should prioritize the loss-framed approach when constructing vaccination slogans to maximize vaccination willingness when vaccines are considered effective at the late implementation stage of the vaccine strategy.

Evolving Altruistic Attitudes towards Vaccination Post COVID-19 Pandemic: A Comparative Analysis across Age Groups

Altruism plays an essential role in promoting vaccine uptake, an issue that came to the fore during the COVID-19 pandemic through discussions of herd immunity and altruistic motivations. In response, the primary objective of this cross-sectional survey was to explore how altruistic attitudes have evolved in the post-pandemic era and to assess their effectiveness in motivating vaccination behavior in different age groups. The study aimed to elucidate changes in altruistic motivations for vaccination and their implications for public health strategies. Using a representative sample of the adult population of South Tyrol, Italy, including 1388 participants, altruism was assessed in 2023 with the scales of the Elderly Care Research Center (ECRC) and the International Personality Item Pool (IPIP) subscale of the version 5F30F-R1. Its association with demographic variables, vaccination attitudes and personal beliefs in two age groups (18-69 years, 70+ years) was analyzed. The results reveal distinct predictors of altruism across these scales and age groups, suggesting a shift in altruistic attitudes towards vaccination when comparing data from a similar survey conducted in 2021 with the 2023 results. Consequently, the use of altruism scales for different age groups is warranted. This study highlights the need for further research in this field. It concludes that while promoting altruistic behavior to increase vaccine uptake appears to be effective primarily among the younger population, emphasizing personal safety is more appropriate for encouraging vaccination among older individuals.

Psychological Factors of Vaccination Intent among Healthcare Providers, Parents, and Laypeople

The interrelatedness of social-structural aspects and psychological features with vaccination intention provides the context to explore personal psychological features related to vaccination. Specifically, we focused on general decision making and vaccine-related dispositions, and their contribution to the intention to vaccinate, within post-pandemic circumstances, after the imposed possibility of choosing a vaccine brand. Our study aimed to map the function (promotive, protective, risk, vulnerability) of a set of personal psychological aspects in the intention to vaccinate among people holding different social roles regarding the vaccination. We surveyed three samples of people: healthcare providers (HPs), parents, and laypeople, within the post-pandemic context. Negative vaccine attitudes lower intention to vaccinate in all regression models (all βs ranging from -0.128 to -0.983, all ps < 0.01). The main results indicate that, regardless of the sample/social role, there is a shared attitudinal core for positive vaccination intention. This core consists of [high] trust in large corporations, government, and healthcare systems, as well as perceived consensus on vaccine safety/efficacy and experience of freedom (protective factors), and [low] vaccination conspiracy beliefs, trust in social media, and choice overload (risk and vulnerability factors, respectively). There are no common promotive factors of intention to vaccinate: for parents, perceived consensus on vaccines, and trust in corporations and the healthcare system, play such roles; for HPs, the experience of freedom is obtained as a unique promotive factor. In contrast, for laypeople, no unique promotive factors were found. Our findings provide insights into the function of psychological factors of vaccination intention across different social roles, particularly healthcare providers, parents, and laypeople, and emphasize the need for tailored immunization interventions in the post-pandemic landscape.

Behavioral interventions for vaccination uptake: A systematic review and meta-analysis

BACKGROUND

Human behavior and more specifically behavioral insight-based approaches to vaccine uptake have often been overlooked. While there have been a few narrative reviews indexed in Medline on behavioral interventions to increase vaccine uptake, to our knowledge, none have been systematic reviews and meta-analyses covering not just high but also low-and-middle income countries.

METHODS

We included 613 studies from the Medline database in our systematic review and meta-analysis categorizing different behavioral interventions in 9 domains: education campaigns, on-site vaccination, incentives, free vaccination, institutional recommendation, provider recommendation, reminder and recall, message framing, and vaccine champion. Additionally, considering that there is variability in the acceptance of vaccines among different populations, we assessed studies from both high-income countries (HICs) and low- to middle-income countries (LMICs), separately.

FINDINGS

Our results showed that behavioral interventions can considerably improve vaccine uptake in most settings. All domains that we examined improved vaccine uptake with the highest effect size associated with provider recommendation (OR: 3.4 (95%CI: 2.5-4.6); Domain: motivation) and on-site vaccination (OR: 2.9 (95%CI: 2.3-3.7); Domain: practical issues). While the number of studies conducted in LMICs was smaller, the quality of studies was similar with those conducted in HICs. Nevertheless, there were variations in the observed effect sizes.

INTERPRETATION

Our findings indicate that "provider recommendation" and "on-site vaccination" along with other behavioral interventions can be employed to increase vaccination rates globally.

Does the Message Frame Promote People's Willingness to Vaccinate when they Worry about Side Effects from the COVID-19 Vaccine? Evidence from an Online Survey Experiment in China

Vaccination is an effective strategy for controlling the coronavirus disease 2019 (COVID-19) pandemic. However, worrying about side effects (WSE) from the COVID-19 vaccine is the leading concern making people hesitant to get vaccinated. Regrettably, there are few studies on alleviating the negative impacts of WSE on COVID-19 vaccination. This study aimed to assess whether message framing (gain- and loss-framed) can moderate the impacts of WSE on the willingness to vaccinate. We conducted an online self-administered survey experiment with three groups: control group (non-framed group), gain-framed groups, and loss-framed groups. In total, 981 participants were randomly assigned to one of the three groups, and their willingness to vaccinate themselves, their children, and elderly members was recorded. People with a higher level of WSE exhibited a lower willingness to vaccinate against COVID-19. However, the gain- and loss-framed messages increased people's willingness to vaccinate themselves, their children, and the elderly. Compared to the gain-framed messages, the loss-framed messages had a greater impact on enhancing people's willingness to self-vaccinate, but not on vaccinating their children and the elderly. Although the gain- and loss-framed messages weakened the negative impacts of WSE on the willingness to be vaccinated, their buffer effect was non-significantly different. The findings in this study suggest that a loss-framed messaging strategy could be a valuable tool in disseminating information on vaccination against COVID-19.

How Message Frames Promote People’s Willingness to Get Vaccinated? The Mediation Role of Perceived Net Benefits

Objectives: This study aims to evaluate the association among framed messages (egoism-, altruism-, and loss-framed information), perceived net benefits (PNB), and willingness to receive a COVID-19 vaccine.

Methods: A between-subject survey experiment was designed to assess the above association. A total of 1,316 individuals were included in this study. The participants were randomly assigned to one control group (receiving non-framed information) and three experimental groups (receiving egoism-, altruism-, and loss-framed information). The participants then reported their vaccination willingness and perceived effectiveness and side effects of vaccination. PNB was determined by subtracting the perceived side effects from perceived effectiveness.

Results: Compared with the control group, participants in the experimental groups exhibited stronger vaccination willingness. Higher PNB levels were associated with enhanced vaccination willingness. However, only loss-framed messages indirectly affected vaccination willingness through PNB.

Conclusion: PNB can mediate the impact of message framing on vaccination willingness. However, the mediation effect of PNB was only found in the relationship between loss-framed messages and vaccination willingness.

Attitudes towards mandatory vaccination and sanctions for vaccination refusal

AIMS

Investigating attitudes towards mandatory vaccination and sanctions for vaccination refusal in an area with insufficient vaccination coverage may help health authorities to assess which strategies for increasing vaccination coverage are appropriate. This study examines attitudes to vaccine mandates and asks questions regarding what kinds of sanctions could legitimately result from vaccination refusal. It seeks to find out if people's attitudes towards mandates and towards sanctions for vaccination refusal are related to their attitudes to vaccines and the degree of trust they feel towards health care professionals and health care authorities. The study also discusses how the observed attitudes towards mandates may be related to perceptions of autonomy, responsibility, and equitability.

METHODS

Data collection was carried out in Finland through an online survey in a region with suboptimal vaccine uptake. Statistical analysis was conducted on a sample of 1101 respondents, using confirmatory factor analysis and structural regression analysis.

RESULTS

Persons hold different views on mandates and sanctions. Importantly, the persons who support vaccination mandates and sanctions for vaccination refusal are to a great degree the same people who have positive attitudes to vaccines and high trust in health care professionals and health authorities.

CONCLUSION

Trust is a key factor which has a bearing on people's attitudes towards mandates and sanctions for noncompliance. A focus on the reasons for lack of trust, and on how to enhance trust, is a more feasible long-term way (than mandates) to promote large- scale compliance with childhood vaccine programmes in the studied country context.

Manipulating risk of infection and appeal to public benefit increase compliance with infection control measures in a hypothetical pandemic scenario

To limit an infectious outbreak, the public must be informed about the infection risk and be motivated to comply with infection control measures. Perceiving a situation as threatening and seeing benefits to complying may be necessary to motivate for compliance. The current study used a preregistered survey experiment with a 2-by-2 between-subject design to investigate if emphasizing high infection risk and appealing to societal benefits impacted intention to comply with infection control measures. The results from a representative Norwegian sample (N = 2533) show that describing a high (as opposed to low) personal risk scenario had a small main effect on compliance. Further, appealing to public (as opposed to self-interested) benefits also had a small main effect. There was no interaction between risk scenario and motivational emphasis. The results suggest that to maximize compliance, information about disease outbreak should emphasize the individual risk of contracting the disease, and could also underline the public value of limiting infection spread. These findings can inform health authorities about the motives underlying compliance with infection control measures during an infectious disease outbreak.

Who is likely to vacillate in their COVID-19 vaccination decision? Free-riding intention and post-positive reluctance

Despite the actual availability of COVID-19 vaccines to combat the pandemic, many people are still vacillating in their decision to vaccinate. In this study, we considered the effect of two relevant contextual issues on vaccination intention: the number of people infected with COVID-19 is increasing, and the pace of vaccination is gaining speed. Specifically, we hypothesized that having already contracted SARS-CoV-2 (post-positive reluctance) could lead people to underestimate the importance of vaccination. Moreover, as the number of vaccinated people increases, more hesitant people could fall into the free-riding intention category, benefitting from the immunity provided by others' vaccinations. Vaccine hesitancy becomes more critical as the vaccination campaign proceeds: at one point, it will be inevitable to deal with hesitant people. This study is part of a WHO Regional Office for Europe project and involved a representative sample of 5006 Italians interviewed in January-February 2021. In case of post-positive reluctance, both young age and female gender increase vaccine hesitancy, while a high level of education reduces free-riding intention. Considering post-positive reluctance and free riding, a protective effect on hesitancy is associated with negative affective states, adherence to protective behaviors, trust in health information sources, and resilience. In contrast, increased vaccine hesitancy is associated with a high level of conspiracy-mindedness and trust in media information sources. Recognizing and studying the post-positive reluctance and the phenomenon of free-riding people can help us to become more efficient in combatting the virus.

Collective Value Promotes the Willingness to Share Pro-Vaccination Messages on Social Media in China: A Randomized Controlled Trial (Preprint)

Background

The proliferation of vaccine misinformation on social media has seriously corrupted the public’s confidence in vaccination. Proactively sharing provaccination messages on social media is a cost-effective way to enhance global vaccination rates and resist vaccine misinformation. However, few strategies for encouraging the public to proactively share vaccine-related knowledge on social media have been developed.

Objective

This research examines the effect of value type (individual vs collective) and message framing (gain vs loss) on influenza vaccination intention (experiment 1) and the willingness to share provaccination messages (experiment 2) among Chinese adults during the COVID-19 pandemic. The primary aim was to evaluate whether messages that emphasized collective value were more effective in increasing the willingness to share than messages that emphasized individual value.

Methods

We enrolled 450 Chinese adults for experiment 1 (n=250, 55.6%) and experiment 2 (n=200, 44.4%). Participants were randomly assigned to individual-gain, individual-loss, collective-gain, or collective-loss conditions with regard to the message in each experiment using the online survey platform’s randomization function. Experiment 1 also included a control group. The primary outcome was influenza vaccination intention in experiment 1 and the willingness to share provaccination messages in experiment 2.

Results

The valid sample included 213 adults in experiment 1 (females: n=151, 70.9%; mean age 29 [SD 9] years; at least some college education: n=202, 94.8%; single: n=131, 61.5%) and 171 adults in experiment 2 (females: n=106, 62.0%; mean age 28 [SD 7] years; at least some college education: n=163, 95.3%; single: n=95, 55.6%). Influenza vaccination intention was stronger in the individual-value conditions than in the collective-value conditions (F_3,166=4.96, P=.03, η²=0.03). The reverse result was found for the willingness to share provaccination messages (F_3,165=6.87, P=.01, η²=0.04). Specifically, participants who received a message emphasizing collective value had a higher intention to share the message than participants who read a message emphasizing individual value (F_3,165=6.87, P=.01, η²=0.04), and the perceived responsibility for message sharing played a mediating role (indirect effect=0.23, 95% lower limit confidence interval [LLCI] 0.41, 95% upper limit confidence interval [ULCI] 0.07). In addition, gain framing facilitated influenza vaccination intention more than loss framing (F_3,166=5.96, P=.02, η²=0.04). However, experiment 2 did not find that message framing affected message-sharing willingness. Neither experiment found an interaction between value type and message framing.

Conclusions

Strengthened individual value rather than collective value is more likely to persuade Chinese adults to vaccinate. However, these adults are more likely to share a message that emphasizes collective rather than individual value, and the perceived responsibility for message sharing plays a mediating role.

What Strategy Is Better for Promoting COVID-19 Vaccination? A Comparison Between Gain-Framed, Loss-Framed, and Altruistic Messages

BACKGROUND/OBJECTIVE

Vaccination is an efficient public health strategy for controlling infectious diseases like the COVID-19 pandemic. Therefore, this study evaluates the effect of gain-framed, loss-framed, and altruism messages on willingness to get a COVID-19 vaccine and confirms the best strategy for promoting vaccination.

METHODS

Herein, we designed an online survey experiment, including a control (exposure to non-framed information) and three experimental (exposure to gain-framed, loss-framed, or altruistic messages) groups, to assess the vaccination willingness. All participants (n = 1316) were randomly assigned into one of the four groups.

RESULTS

The individuals exposed to gain-framed, loss-framed, or altruism messages exhibited a higher willingness to get a COVID-19 vaccine than those exposed to non-framed information. Moreover, the loss-framed information effect on vaccination willingness was more substantial than the other two messages. However, no significant difference was observed between the gain-framed and altruism messages.

CONCLUSION

This study suggests that a loss-framed information dissemination strategy could be preferable to motivate vaccination willingness against COVID-19.

Critical interpretative synthesis of herd immunity for COVID-19 pandemic

Introduction:

Countries globally are evaluating the concept of herd immunity and its critical role in the control of pandemic. The current paper attempts to conduct a critical interpretative synthesis (CIS) on the role of herd immunity in current COVID-19 pandemic.

Methods:

CIS is tool for developing theoretical framework using interpretation drawn from relevant empirical and non-empirical sources. This review is done by formulating review question for literature search. Purposive sampling of literature was done followed by reciprocal translational analysis of extracted data.

Results:

Herd immunity is indirect protection from a contagious infectious disease when a population is immune either through vaccination or natural immunity developed through previous infection. The reproduction number for COVID-19 in India was found to be 2.56 and herd immunity threshold as 61%.

Discussion:

Exposing 71% young population in India to the SARS-CoV-2 infection can achieve herd immunity but with high morbidity as well as mortality. Vaccine are under process. Feco-oral transmission and reinfection of COVID 19 are major factors to develop or break the circle of herd immunity in community. “Immunity passport” can give false sense of security. Surveillance and seroprevalence studies assess immunity status, gradual exposure of infection to younger population and collaborative partnerships on organizations are few strategies to acquire herd immunity.

Conclusion:

Herd immunity is a measure for prevention and control of COVID-19 pandemic against the backdrop of mortality and morbidity. Vaccine can be boon but if herd immunity is to be acquired by natural infection then preparedness is necessary.

Responsibility Considerations and the Design of Health Care Policies: A Survey Study of the Norwegian Population

The objective of this article is to explore people's attitudes toward responsibility in the allocation of public health care resources. Special attention is paid to conceptualizations of responsibility involving blame and sanctions. A representative sample of the Norwegian population was asked about various responsibility mechanisms that have been proposed in the theoretical literature on health care and personal responsibility, from denial of treatment to a tax on unhealthy consumer goods. Survey experiments were employed to study treatment effects, such as whether fairness considerations affect attitudes about responsibility. We find that, overall, a substantial minority of the respondents find it fair to let the health care system sanction people-in one way or another-for voluntary behaviors that increase the risk of becoming ill. Quite surprisingly, we find that people are more prone to report that they should themselves be held responsible for unhealthy lifestyles than others.

A Web Application About Herd Immunity Using Personalized Avatars: Development Study

BACKGROUND

Herd immunity or community immunity refers to the reduced risk of infection among susceptible individuals in a population through the presence and proximity of immune individuals. Recent studies suggest that improving the understanding of community immunity may increase intentions to get vaccinated.

OBJECTIVE

This study aims to design a web application about community immunity and optimize it based on users' cognitive and emotional responses.

METHODS

Our multidisciplinary team developed a web application about community immunity to communicate epidemiological evidence in a personalized way. In our application, people build their own community by creating an avatar representing themselves and 8 other avatars representing people around them, for example, their family or coworkers. The application integrates these avatars in a 2-min visualization showing how different parameters (eg, vaccine coverage, and contact within communities) influence community immunity. We predefined communication goals, created prototype visualizations, and tested four iterative versions of our visualization in a university-based human-computer interaction laboratory and community-based settings (a cafeteria, two shopping malls, and a public library). Data included psychophysiological measures (eye tracking, galvanic skin response, facial emotion recognition, and electroencephalogram) to assess participants' cognitive and affective responses to the visualization and verbal feedback to assess their interpretations of the visualization's content and messaging.

RESULTS

Among 110 participants across all four cycles, 68 (61.8%) were women and 38 (34.5%) were men (4/110, 3.6%; not reported), with a mean age of 38 (SD 17) years. More than half (65/110, 59.0%) of participants reported having a university-level education. Iterative changes across the cycles included adding the ability for users to create their own avatars, specific signals about who was represented by the different avatars, using color and movement to indicate protection or lack of protection from infectious disease, and changes to terminology to ensure clarity for people with varying educational backgrounds. Overall, we observed 3 generalizable findings. First, visualization does indeed appear to be a promising medium for conveying what community immunity is and how it works. Second, by involving multiple users in an iterative design process, it is possible to create a short and simple visualization that clearly conveys a complex topic. Finally, evaluating users' emotional responses during the design process, in addition to their cognitive responses, offers insights that help inform the final design of an intervention.

CONCLUSIONS

Visualization with personalized avatars may help people understand their individual roles in population health. Our app showed promise as a method of communicating the relationship between individual behavior and community health. The next steps will include assessing the effects of the application on risk perception, knowledge, and vaccination intentions in a randomized controlled trial. This study offers a potential road map for designing health communication materials for complex topics such as community immunity.

Determining optimal community protection strategies for the influenza vaccine

Introduction: Seasonal influenza poses a major risk to the health of the population. Optimal strategies for influenza vaccination can help to reduce this risk. Areas covered: Systematic evaluations of the burden of influenza are first reviewed. Key meta-analysis, randomized trials, and observational studies are critically reviewed to provide the best estimates of the efficacy of influenza vaccine. The concept of herd effect is first introduced and this is followed by the rationale and the evidence to support herd effect that can be provided with strategic use of influenza vaccination in populations. Challenges including the effect of repeated influenza vaccination and vaccine hesitancy are reviewed. The citations were selected by the authors based on PubMed searches of the literature. Expert opinion: Efforts to develop new vaccines, including a universal vaccine, offer the best prospects for improved herd effect. Increasing uptake in new populations can increase likelihood of a herd effect.