Letters designed with behavioural science increase influenza vaccination in Medicare beneficiaries

Rationale and design of NUDGE-FLU-CHRONIC and NUDGE-FLU-2: Two nationwide randomized trials of electronic nudges to increase influenza vaccination among patients with chronic diseases and older adults during the 2023/2024 influenza season

BACKGROUND

Yearly influenza vaccination is strongly recommended for older adults and patients with chronic diseases including cardiovascular disease (CVD); however, vaccination rates remain suboptimal, particularly among younger patients. Electronic letters incorporating behavioral nudges are highly scalable public health interventions which can potentially increase vaccination, but further research is needed to determine the most effective strategies and to assess effectiveness across different populations. The purpose of NUDGE-FLU-CHRONIC and NUDGE-FLU-2 are to evaluate the effectiveness of electronic nudges delivered via the Danish governmental electronic letter system in increasing influenza vaccination among patients with chronic diseases and older adults, respectively.

METHODS

Both trials are designed as pragmatic randomized implementation trials enrolling all Danish citizens in their respective target groups and conducted during the 2023/2024 influenza season. NUDGE-FLU-CHRONIC enrolls patients aged 18-64 years with chronic diseases. NUDGE-FLU-2 builds upon the NUDGE-FLU trial conducted in 2022/2023 and aims to expand the evidence by testing both previously successful and new nudges among adults ≥65 years during a subsequent influenza season. Persons with exemptions from the electronic letter system are excluded from both trials. In both trials, participants are randomized in a 2.45:1:1:1:1:1:1 ratio to either receive no electronic letter (usual care) or to receive one of 6 different behaviorally informed electronic letters. NUDGE-FLU-CHRONIC has randomized 299,881 participants with intervention letters delivered on September 24, 2023, while NUDGE-FLU-2 has randomized 881,373 participants and delivered intervention letters on September 13, 2023. Follow-up is currently ongoing. In both trials, the primary endpoint is receipt of influenza vaccination on or before January 1, 2024, and the secondary endpoint is time to vaccination. Clinical outcomes including respiratory and cardiovascular hospitalizations, all-cause hospitalization, and mortality are included as prespecified exploratory endpoints. Prespecified individual-level pooled analyses will be conducted across NUDGE-FLU, NUDGE-FLU-CHRONIC, and NUDGE-FLU-2.

DISCUSSION

NUDGE-FLU-CHRONIC is the first nationwide randomized trial of electronic nudges to increase influenza vaccination conducted among 18-64-year-old high-risk patients with chronic diseases. NUDGE-FLU-2 will provide further evidence on the effectiveness of electronic nudges among older adults ≥65 years. Collectively, the NUDGE-FLU trials will provide an extensive evidence base for future public health communications.

TRIAL REGISTRATION

NUDGE-FLU-CHRONIC: Clinicaltrials.gov: NCT06030739, registered September 11, 2023, https://clinicaltrials.gov/study/NCT06030739. NUDGE-FLU-2: Clinicaltrials.gov: NCT06030726, registered September 11, 2023, https://clinicaltrials.gov/study/NCT06030726.

Implicit theories of health predict influenza vaccination intention among elder Chinese: The mediating role of anticipated regret

Receiving influenza vaccines is the most effective public health strategy to protect people against seasonal flu infection. However, influenza vaccination rates are extremely low in China. This study investigated the association between implicit theories of health and influenza vaccination intention among elder Chinese when the vaccine is free (vs not free), and examined the mediating effect of anticipated regret. The results suggested that implicit theories of health, especially incremental theory of health, significantly predicted Chinese elders' influenza vaccination intention and this relationship was mediated by anticipated regret. Implications of the current research for promoting influenza vaccination among elder Chinese and directions for future research are discussed.

Evaluating the impact of school-based influenza vaccination programme on absenteeism and outbreaks at schools in Hong Kong: a retrospective cohort study protocol

INTRODUCTION

Seasonal influenza causes annual school breaks and student absenteeism in Hong Kong schools and kindergartens. This proposal aims to conduct a retrospective cohort study to evaluate the impact of a school-based influenza vaccination (SIV) programme on absenteeism and outbreaks at schools in Hong Kong.

METHODS

The study will compare schools that implemented the SIV programme with schools that did not. The data will be sourced from school records, encompassing absenteeism records, outbreak reports, and vaccination rates. We will recruit 1000 students from 381 schools and kindergartens in 18 districts of Hong Kong starting June 2024. The primary outcome measures will include absenteeism rates due to influenza and school influenza outbreaks. Secondary outcomes will consist of vaccination coverage rates and the impact of the SIV programme on hospitalisations due to influenza-like illness. A t-test will be conducted to compare the outcomes between schools with and without the SIV programme.

ETHICS AND DISSEMINATION

The school completed signing the participants' informed consent form before reporting the data to us. Our study has been approved by the Hospital Authority Hong Kong West Cluster IRB Committee (IRB No: UW 17-111) and was a subtopic of the research "The estimated age-group specific influenza vaccine coverage rates in Hong Kong and the impact of the school outreach vaccination program".

TRIAL REGISTRATION

This study will be retrospectively registered.

The Nudging Effect of a Reminder Letter to Reduce Duplicated Medications: A Randomized Controlled Trial

BACKGROUND

The increasing trend of multiple chronic conditions across the world has worsened the problem of medication duplication in health care systems without gatekeeping or referral requirement. Thus, to overcome this problem, a reminder letter has been developed in Taiwan to nudge patients to engage in medication management.

OBJECTIVE

To evaluate the effect of reminder letter on reducing duplicated medications.

RESEARCH DESIGN

A 2-arm randomized controlled trial design.

SUBJECTS

Patients with duplicated medications in the first quarter of 2019.

MEASURES

The Taiwanese single-payer National Health Insurance Administration identified the eligible patients for this study. A postal reminder letter regarding medication duplication was mailed to the patients in the study group, and no information was provided to the comparison group. Generalized estimation equation models with a difference-in-differences analysis were used to estimate the effects of the reminder letters.

RESULTS

Each group included 11,000 patients. Those who had received the reminder letter were less likely to receive duplicated medications in the subsequent 2 quarters (postintervention 1: odds ratio [OR]=0.95, 95% CI=0.87-1.03; postintervention_2: OR=0.99, 95% CI=0.90-1.08) and had fewer days of duplicated medications (postintervention 1: β=-0.115, P =0.015; postintervention 2 (β=-0.091, P =0.089) than those who had not received the reminder letter, showing marginal but significant differences.

CONCLUSIONS

A one-off reminder letter nudge could mildly decrease the occurrence of duplicated medications. Multiple nudges or nudges incorporating behavioral science insights may be further considered to improve medication safety in health systems without gatekeeping.

Clinical Outcomes With Electronic Nudges to Increase Influenza Vaccination : A Prespecified Analysis of a Nationwide, Pragmatic, Registry-Based, Randomized Implementation Trial

BACKGROUND

In the NUDGE-FLU (Nationwide Utilization of Danish Government Electronic letter system for increasing inFLUenza vaccine uptake) trial, electronic letters incorporating cardiovascular (CV) gain-framing and repeated messaging increased influenza vaccination by approximately 1 percentage point.

OBJECTIVE

To evaluate the effects of the successful nudging interventions on downstream clinical outcomes.

DESIGN

Prespecified exploratory analysis of a nationwide randomized implementation trial. (ClinicalTrials.gov: NCT05542004).

SETTING

The 2022 to 2023 influenza season.

PARTICIPANTS

964 870 Danish citizens aged 65 years or older.

INTERVENTION

Usual care or 9 different electronically delivered behavioral nudging letters.

MEASUREMENTS

Cardiovascular, respiratory, and other clinical end points during follow-up from intervention delivery (16 September 2022) through 31 May 2023.

RESULTS

The analysis set included 691 820 participants. Hospitalization for pneumonia or influenza occurred in 3354 of 346 327 (1.0%) participants in the usual care group, 396 of 38 586 (1.0%) in the CV gain-framing group (hazard ratio [HR], 1.06 [95% CI, 0.95 to 1.18]; versus usual care), and 403 of 38 231 (1.1%) in the repeated letter group (HR, 1.09 [CI, 0.98 to 1.21]; versus usual care). In the usual care group, 44 682 (12.9%) participants were hospitalized for any cause, compared with 5002 (13.0%) in the CV gain-framing group (HR, 1.00 [CI, 0.97 to 1.03]; versus usual care) and 4965 (13.0%) in the repeated letter group (HR, 1.01 [CI, 0.98 to 1.04]; versus usual care). A total of 6341 (1.8%) participants died in the usual care group, compared with 721 (1.9%) in the CV gain-framing group (HR, 1.02 [CI, 0.94 to 1.10]; versus usual care) and 646 (1.7%) in the repeated letter group (HR, 0.92 [CI, 0.85 to 1.00]; versus usual care).

LIMITATION

Prespecified but exploratory analysis, potential misclassification of events in routinely collected registry data, and results may not be generalizable to other health systems or countries with other racial compositions and/or cultural or societal norms.

CONCLUSION

In a prespecified exploratory analysis, modest increases in influenza vaccination rates seen with electronic nudges did not translate into observable improvements in clinical outcomes. Seasonal influenza vaccination should remain strongly recommended.

PRIMARY FUNDING SOURCE

Sanofi.

The Framing Effect of Digital Textual Messages on Uptake Rates of Medical Checkups: Field Study

BACKGROUND

Health care authorities often use text messages to enhance compliance with medical recommendations. The effectiveness of different message framings has been studied extensively over the past 3 decades. Recently, health care providers have begun using digital media platforms to disseminate health-related messages.

OBJECTIVE

This study aimed to examine the effectiveness of some of the most widely used message framings on the uptake rates of medical checkups.

METHODS

This study used a large-scale digital outreach campaign conducted by Maccabi Healthcare Services (MHS) during 2020-2021, involving a total of 113,048 participants. MHS members aged 50-74 years were invited to take their recommended medical actions from the following list: human papillomavirus (HPV), mammography, abdominal aortic aneurysm, fecal occult blood test (FOBT), and pneumococcal vaccination. Each member was randomly assigned to receive 1 of 6 message framings: control (neutrally framed; n=20,959, 18.5%), gains (benefits of compliance; n=20,393, 18%), losses (negative consequences of noncompliance; n=15,165, 13.4%), recommendation (a recommendation by an authoritative figure, in this context by a physician; n=20,584, 18.2%), implementation intentions (linking potential outcomes to future reactions; n=20,701, 18.3%), and empowerment (emphasizing personal responsibility for maintaining good health; n=15,246, 13.5%). The time frames for measuring a successful intervention were 14 days for scheduling screenings (ie, HPV, mammography, or abdominal aortic aneurysm), 30 days for performing the FOBT, and 60 days for receiving pneumococcal vaccination. We also examined the effectiveness of media channels (text message or email) on uptake rates and whether the subject-line length is correlated with message-opening rates.

RESULTS

No significant effect of message framing on uptake rates of medical checkups was observed. The rates of appointments for screening ranged from 12.9% to 14.1% across treatments. Based on a chi-square test, there was no evidence to reject the null hypothesis that these compliance rates are independent of the treatments (P=.35). The uptake rates for the FOBT and pneumococcal vaccination ranged from 23.3% to 23.8% across treatments, and we could not reject the hypothesis that they are independent of the treatments (P=.88). We also found that emails are more effective than text messages (P<.001) and that the subject-line length is negatively correlated with message-opening rates.

CONCLUSIONS

No evidence was found for an effect of the 5 message framings on uptake rates of medical checkups. To enhance compliance rates, public health officials may consider alternative framings. Furthermore, media channels and the subject-line length should be given careful consideration in the planning stages of health care campaigns.

TRIAL REGISTRATION

AEA RCT Registry AEARCTR-0006317; https://www.socialscienceregistry.org/trials/6317/history/201365.

Effectiveness of Multifaceted Strategies to Increase Influenza Vaccination Uptake: A Cluster Randomized Trial

Importance

Influenza vaccination rates remain low among primary school students and vary by school in Beijing, China. Theory-informed, multifaceted strategies are needed to improve influenza vaccination uptake.

Objective

To evaluate the effectiveness of multifaceted strategies in improving influenza vaccination uptake among primary school students.

Design, Setting, and Participants

This cluster randomized trial was conducted from September 2022 to May 2023 across primary schools in Beijing, China. Schools were allocated randomly in a 1:1 ratio to multifaceted strategies or usual practice. Schools were deemed eligible if the vaccination rates in the 2019 to 2020 season fell at or below the district-wide average for primary schools. Eligible participants included students in grades 2 and 3 with no medical contraindications for influenza vaccination.

Intervention

The multifaceted strategies intervention involved system-level planning and coordination (eg, developing an implementation blueprint, building social norms, and enhancing supervision), school-level training and educating school implementers (eg, conducting a 1-hour training and developing educational materials), and individual-level educating and reminding students and parents (eg, conducting educational activities and sending 4 reminders about vaccination).

Main Outcomes and Measures

The primary outcomes were influenza vaccination uptake at school reported by school clinicians as well as overall vaccine uptake either at school or outside of school as reported by parents at 3 months. Generalized linear mixed models were used for analysis.

Results

A total of 20 schools were randomized. One intervention school and 2 control schools did not administer vaccination on school grounds due to COVID-19, resulting in a total of 17 schools (9 intervention and 8 control). There was a total of 1691 students aged 7 to 8 years (890 male [52.6%]; 801 female [47.4%]) including 915 in the intervention group and 776 in the control group. Of all participants, 848 (50.1%) were in grade 2, and 1209 (71.5%) were vaccinated in the 2021 to 2022 season. Participants in the intervention and control groups shared similar characteristics. At follow-up, of the 915 students in the intervention group, 679 (74.5%) received a vaccination at school, and of the 776 students in the control group, 556 (71.7%) received a vaccination at school. The overall vaccination rates were 76.0% (695 of 915 students) for the intervention group and 71.3% (553 of 776 students) for the control group. Compared with the control group, there was significant improvement of vaccination uptake at school (odds ratio, 1.40; 95% CI, 1.06-1.85; P = .02) and overall uptake (odds ratio, 1.49; 95% CI, 1.12-1.99; P = .01) for the intervention group.

Conclusions and Relevance

In this study, multifaceted strategies showed modest effectiveness in improving influenza vaccination uptake among primary school students, which provides a basis for the implementation of school-located vaccination programs of other vaccines in China, and in other countries with comparable programs.

Trial registration

Chinese Clinical Trial Registry: ChiCTR2200062449.

Strategies to increase the coverage of influenza and pneumonia vaccination in older adults: a systematic review and network meta-analysis

BACKGROUND

It is urgent to implement interventions to increase vaccination rates of influenza/pneumonia vaccines in older adults, yet the effectiveness of different intervention strategies has not been thoroughly evaluated.

OBJECTIVE

We aimed to assess the effectiveness of intervention strategies for increasing the coverage of influenza/pneumonia vaccination in older adults.

METHODS

PubMed, Web of Science, Cochrane Library, Embase, China Biology Medicine disc, China National Knowledge Infrastructure and Wanfang were searched from 1 January 2000 to 1 October 2022. RCTs that assessed any intervention strategies for increasing influenza/pneumonia vaccination coverage or willingness in older adults were included. A series of random-effects network meta-analysis was conducted by using frequentist frameworks.

RESULTS

Twenty-two RCTs involving 385,182 older participants were eligible for further analysis. Eight types of intervention strategies were evaluated. Compared with routine notification, health education (odds ratio [OR], 1.85 [95%CI, 1.19 to 2.88]), centralised reminder (OR, 1.63 [95%CI, 1.07 to 2.47]), health education + onsite vaccination (OR, 2.89 [95%CI, 1.30 to 6.39]), and health education + centralised reminder + onsite vaccination (OR, 20.76 [95%CI, 7.33 to 58.74]) could effectively improve the vaccination rate. The evidence grade was low or very low due to the substantial heterogeneity among studies.

CONCLUSIONS

Our findings suggest that health education + centralised reminder + onsite vaccination may potentially be an effective strategy regardless of cost, but the evidence level was low. More rigorous trials are needed to identify the association between strategies and vaccination rates among older adults and to integrate such evidence into clinical care to improve vaccination rates.

Last-mile delivery increases vaccine uptake in Sierra Leone

Less than 30% of people in Africa received a dose of the COVID-19 vaccine even 18 months after vaccine development1. Here, motivated by the observation that residents of remote, rural areas of Sierra Leone faced severe access difficulties2, we conducted an intervention with last-mile delivery of doses and health professionals to the most inaccessible areas, along with community mobilization. A cluster randomized controlled trial in 150 communities showed that this intervention with mobile vaccination teams increased the immunization rate by about 26 percentage points within 48-72 h. Moreover, auxiliary populations visited our community vaccination points, which more than doubled the number of inoculations administered. The additional people vaccinated per intervention site translated to an implementation cost of US $33 per person vaccinated. Transportation to reach remote villages accounted for a large share of total intervention costs. Therefore, bundling multiple maternal and child health interventions in the same visit would further reduce costs per person treated. Current research on vaccine delivery maintains a large focus on individual behavioural issues such as hesitancy. Our study demonstrates that prioritizing mobile services to overcome access difficulties faced by remote populations in developing countries can generate increased returns in terms of uptake of health services3.

The impact of using reinforcement learning to personalize communication on medication adherence: findings from the REINFORCE trial

Text messaging can promote healthy behaviors, like adherence to medication, yet its effectiveness remains modest, in part because message content is rarely personalized. Reinforcement learning has been used in consumer technology to personalize content but with limited application in healthcare. We tested a reinforcement learning program that identifies individual responsiveness ("adherence") to text message content and personalizes messaging accordingly. We randomized 60 individuals with diabetes and glycated hemoglobin A1c [HbA1c] ≥ 7.5% to reinforcement learning intervention or control (no messages). Both arms received electronic pill bottles to measure adherence. The intervention improved absolute adjusted adherence by 13.6% (95%CI: 1.7%-27.1%) versus control and was more effective in patients with HbA1c 7.5- < 9.0% (36.6%, 95%CI: 25.1%-48.2%, interaction p < 0.001). We also explored whether individual patient characteristics were associated with differential response to tested behavioral factors and unique clusters of responsiveness. Reinforcement learning may be a promising approach to improve adherence and personalize communication at scale.

Nudging a Nation - The Danish NUDGE Trial Concept

Danish NUDGE Trial ConceptRandomized encouragement trials randomize to an opportunity to receive treatment instead of to the treatment. Here, Johansen and colleagues combine randomized encouragement trials with several advantages inherent in the Danish health system.

A review of factors influencing vaccination policies and programs for older adults globally

Policies and programs to increase vaccine coverage rates among adults 50 years of age or older are limited and vaccine uptake is often suboptimal. Our review evaluated evidence on the effectiveness and success of adult-targeted vaccination interventions and identified literature gaps. Literature was retrieved (2021) from PubMed, Embase, and Google Scholar databases. Outcomes assessed included data on an intervention's effectiveness and impact on vaccine uptake. Interventions were characterized thematically: affordability (n = 9), awareness (n = 25), and vaccination access (n = 6); and included influenza, pneumococcal, tetanus-containing, and herpes zoster vaccines. Interactive interventions directed toward patients, including provider-led educational initiatives and provider recommendations showed more positive associations than less interactive interventions, such as posters and reminder-recall letters. Provider interventions, including awareness campaigns, incentives, affordability efforts, or vaccination site expansion generally showed positive associations. Combining interventions was found to be successful across several studies. Barriers and interventions varied for population subgroups, therefore, tailoring programs is critical.

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.

A large-scale observational study of the causal effects of a behavioral health nudge

Nudges are interventions promoting healthy behavior without forbidding options or substantial incentives; the Apple Watch, for example, encourages users to stand by delivering a notification if they have been sitting for the first 50 minutes of an hour. On the basis of 76 billion minutes of observational standing data from 160,000 subjects in the public Apple Heart and Movement Study, we estimate the causal effect of this notification using a regression discontinuity design for time series data with time-varying treatment. We show that the nudge increases the probability of standing by up to 43.9% and remains effective with time. The nudge's effectiveness increases with age and is independent of gender. Closing Apple Watch Activity Rings, a visualization of participants' daily progress in Move, Exercise, and Stand, further increases the nudge's impact. This work demonstrates the effectiveness of behavioral health interventions and introduces tools for investigating their causal effect from large-scale observations.

Electronic Reminder to Transition Care After Hypertensive Disorders of Pregnancy: A Randomized Controlled Trial

OBJECTIVE

Scalable interventions are needed to improve preventive care for those with increased cardiovascular disease (CVD) risk identified during pregnancy. We hypothesized that an automated reminder message for clinicians (nudge) would increase counseling at the postpartum visit on patient transitions of care.

METHODS

We conducted a single-center, randomized controlled trial including birthing people with a hypertensive disorder of pregnancy evaluating a nudge compared with usual care. The nudge, including counseling phrases and patient-specific information on hypertensive diagnosis, was sent to the obstetric clinician through the electronic medical record up to 7 days before the postpartum visit. The primary outcome was documentation of counseling on transitions of care to primary care or cardiology. Secondary outcomes were documentation of CVD risk, use of counseling phrases, and preventive care visit within 6 months. A sample size of 94 per group (n=188) was planned to compare the nudge intervention with usual care; given the anticipated loss to follow-up, the sample size was increased to 222. Intention-to-treat analyses were performed, with P <.05 considered significant.

RESULTS

From February to June 2021, 392 patients were screened, and 222 were randomized and analyzed. Of these, 205 (92.3%) attended a postpartum visit. Groups were similar, but more women in the usual care group had diabetes (16.1% vs 6.7%, P =.03). After adjustment for diabetes, patients in the nudge group were more likely to have documented counseling on transitions of care (38.8% vs 26.2%, adjusted relative risk [aRR] 1.53, 95% CI 1.02-2.31), CVD risk (21.4% vs 8.4%, aRR 2.57, 95% CI 1.20-5.49), and use of aspirin in a future pregnancy (14.3% vs 1.9%, aRR 7.49, 95% CI 1.66-33.93). Counseling phrases were used more often in the nudge group (11.2% vs 0.9%, aRR 12.27, 95% CI 1.50-100.28). Preventive care visit attendance did not differ by group (22.1% vs 24.6%, aRR 0.91, 95% CI 0.57-1.47).

CONCLUSION

A timely electronic reminder to obstetric clinicians improved counseling about transitions of care after hypertensive disorders of pregnancy but did not result in increased preventive care visit attendance.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov , NCT04660032.

Electronic nudges to increase influenza vaccination uptake in Denmark: a nationwide, pragmatic, registry-based, randomised implementation trial

BACKGROUND

Influenza vaccination rates remain suboptimal despite effectiveness in preventing influenza infection and related complications. We investigated whether behavioural nudges, delivered via a governmental electronic letter system, would increase influenza vaccination uptake among older adults in Denmark.

METHODS

We did a nationwide, pragmatic, registry-based, cluster-randomised implementation trial during the 2022-23 influenza season in Denmark. All Danish citizens aged 65 years or older or turning 65 years by Jan 15, 2023 were included. We excluded individuals living in nursing homes and individuals who had an exemption from the Danish mandatory governmental electronic letter system. Households were randomly assigned (9:1:1:1:1:1:1:1:1:1) to usual care or nine different electronic letters designed on the basis of different behavioural nudging concepts. Data were sourced from nationwide Danish administrative health registries. The primary endpoint was receipt of influenza vaccination on or before Jan 1, 2023. The primary analysis assessed an analytical set of one randomly selected individual per household, and a sensitivity analysis included all randomly assigned individuals and accounted for within-household correlation. The trial is registered with ClinicalTrials.gov, NCT05542004.

FINDINGS

We identified 1 232 938 individuals aged 65 years or older in Denmark and excluded 56 436 (4·6%) individuals living in nursing homes and 211 632 (17·2%) with an exemption from the electronic letter system. We randomly assigned 964 870 (78·3%) participants across 691 820 households. Compared with usual care, influenza vaccination rates were higher in the group receiving an electronic letter highlighting potential cardiovascular benefits of vaccination (81·00% vs 80·12%; difference 0·89 percentage points [99·55% CI 0·29-1·48]; p<0·0001) and the group receiving repeated letters at randomisation and at day 14 (80·85% vs 80·12%; difference 0·73 percentage points [0·13-1·34]; p=0·0006). These strategies improved vaccination rates across major subgroups including those with and without established cardiovascular disease. The cardiovascular gain-framed letter was particularly effective among participants who had not been vaccinated for influenza in the previous season (p_interaction=0·0002). A sensitivity analysis of all randomly assigned individuals accounting for within-household clustering yielded similar findings.

INTERPRETATION

Electronically delivered letters highlighting potential cardiovascular benefits of influenza vaccination or sent again as a reminder significantly increased vaccination uptake across Denmark. Although the magnitude of effectiveness was modest, the low-touch, inexpensive, and highly scalable nature of these electronic letters might be informative for future public health campaigns.

FUNDING

Sanofi.

Using nudges to promote clinical decision making of healthcare professionals: A scoping review

Nudging has been discussed in the context of policy and public health, but not so much within healthcare. This scoping review aimed to assess the empirical evidence on how nudging techniques can be used to affect the behavior of healthcare professionals (HCPs) in clinical settings. A systematic database search was conducted for the period January 2010-December 2020 using the PRISMA extension for Scoping Review checklist. Two reviewers independently screened each article for inclusion. Included articles were reviewed to extract key information about each intervention, including purpose, target behavior, measured outcomes, key findings, nudging strategies, intervention objectives and their theoretical underpinnings. Two independent dimensions, building on Kahneman's System 1 and System 2, were used to describe nudging strategies according to user action and timing of their implementation. Of the included 51 articles, 40 reported statistically significant results, six were not significant and two reported mixed results. Thirteen different nudging strategies were identified aimed at modifying four types of HPCs' behavior: prescriptions and orders, procedure, hand hygiene, and vaccination. The most common nudging strategy employed were defaults or pre-orders, followed by alerts or reminders, and active choice. Many interventions did not require any deliberate action from users, here termed passive interventions, such as automatically changing prescriptions to their generic equivalent unless indicated by the user. Passive nudges may be successful in changing the target outcome but may go unnoticed by the user. Future work should consider the broader ethical implications of passive nudges.

Can financial incentives and other nudges increase COVID-19 vaccinations among the vaccine hesitant? A randomized trial

Despite rapid initial uptake, COVID-19 vaccinations in the United States stalled within a few months of widespread rollout in 2021. In response, many state and local governments, employers and health systems used public health messaging, financial incentives and creative scheduling tools to increase vaccine uptake. Although these approaches drew on evidence from influenza and other vaccination efforts, they were largely untested in the context of SARS-CoV-2. In mid-2021, months after vaccines were widely available, we evaluated vaccination intentions and vaccine uptake using a randomized control trial. To do this, we recruited unvaccinated members of a Medicaid managed care plan in California (n = 2,701) and randomly assigned them to different public health messages, $10 or $50 financial incentives for vaccination, a simple vaccination appointment scheduler, or control. While messages increased vaccination intentions, none of the interventions increased vaccination rates. Estimates for financial incentives rule out even relatively small increases in vaccination rates. Small financial incentives and other behavioral nudges do not meaningfully increase COVID-19 vaccination rates amongst the vaccine hesitant.

Vaccination nudges: A study of pre-booked COVID-19 vaccinations in Sweden

A nudge changes people's actions without removing their options or altering their incentives. During the COVID-19 vaccine rollout, the Swedish Region of Uppsala sent letters with pre-booked appointments to inhabitants aged 16–17 instead of opening up manual appointment booking. Using regional and municipal vaccination data, we document a higher vaccine uptake among 16- to 17-year-olds in Uppsala compared to untreated control regions (constructed using the synthetic control method as well as neighboring municipalities). The results highlight pre-booked appointments as a strategy for increasing vaccination rates in populations with low perceived risk.

Intervention Tournaments: An Overview of Concept, Design, and Implementation

A large portion of research in the social sciences is devoted to using interventions to combat societal and social problems, such as prejudice, discrimination, and intergroup conflict. However, these interventions are often developed using the theories and/or intuitions of the individuals who developed them and evaluated in isolation without comparing their efficacy with other interventions. Here, we make the case for an experimental design that addresses such issues: an intervention tournament-that is, a study that compares several different interventions against a single control and uses the same standardized outcome measures during assessment and participants drawn from the same population. We begin by highlighting the utility of intervention tournaments as an approach that complements other, more commonly used approaches to addressing societal issues. We then describe various approaches to intervention tournaments, which include crowdsourced, curated, and in-house-developed intervention tournaments, and their unique characteristics. Finally, we discuss practical recommendations and key design insights for conducting such research, given the existing literature. These include considerations of intervention-tournament deployment, characteristics of included interventions, statistical analysis and reporting, study design, longitudinal and underlying psychological mechanism assessment, and theoretical ramifications.

Explaining higher Covid-19 vaccination among some US primary care professionals

Background and objective

Research in several countries shows higher Covid-19 vaccination willingness and uptake among physicians than nurses. Our paper aims to characterize and explain this difference.

Methods

In early 2021, we surveyed 1047 U.S. primary care professionals who served adolescents, ages 11–17. The national sample included physicians (71%) as well as nurses and advanced practice providers. The survey assessed the three domains of the Increasing Vaccination Model: thinking and feeling, social processes, and direct behavior change.

Results

Covid-19 vaccine uptake was higher among physicians than among nurses and advanced practice providers (91% vs. 76%, p < .05). Overall, in the thinking and feeling domain, higher confidence in Covid-19 vaccination, higher perceived susceptibility to the disease, and stronger anticipated regret were associated with higher vaccine uptake (all p < .05). In the social processes domain, perceiving more positive social norms for Covid-19 vaccination, receiving recommendations to get the vaccine, and wanting to help others were associated with higher vaccine uptake (all p < .05). In the direct behavior change domain, receiving an invitation to get the vaccine and better access to vaccination were associated with higher uptake (both p < .05). Of these variables, most of the thinking and feeling and social processes variables mediated the association of training with vaccine uptake.

Conclusions

Physicians had higher Covid-19 vaccine uptake than nurses and advanced practice providers, corresponding with their more supportive vaccine beliefs and social experiences. Efforts to reach the remaining unvaccinated cohort can build on these findings.

COVID-19 vaccine hesitancy in eight European countries: Prevalence, determinants, and heterogeneity

We examine heterogeneity in COVID-19 vaccine hesitancy across eight European countries. We reveal striking differences across countries, ranging from 6.4% of adults in Spain to 61.8% in Bulgaria reporting being hesitant. We experimentally assess the effectiveness of different messages designed to reduce COVID-19 vaccine hesitancy. Receiving messages emphasizing either the medical benefits or the hedonistic benefits of vaccination significantly increases COVID-19 vaccination willingness in Germany, whereas highlighting privileges contingent on holding a vaccination certificate increases vaccination willingness in both Germany and the United Kingdom. No message has significant positive effects in any other country. Machine learning-based heterogeneity analyses reveal that treatment effects are smaller or even negative in settings marked by high conspiracy beliefs and low health literacy. In contrast, trust in government increases treatment effects in some groups. The heterogeneity in vaccine hesitancy and responses to different messages suggests that health authorities should avoid one-size-fits-all vaccination campaigns.

Video-based messages to reduce COVID-19 vaccine hesitancy and nudge vaccination intentions

Vaccines are highly effective for curbing the spread of SARS-CoV-2 (COVID-19). Yet, millions of Americans remain hesitant about getting vaccinated, jeopardizing our ability to end the COVID-19 pandemic by fueling the spread and development of new variants. We show that brief video-based messages of encouragement addressing specific COVID-19 vaccine concerns increase vaccination intentions, and that vaccination intentions, in turn, are predictive of future vaccine uptake. Results from our online experiment reveal that willingness to get vaccinated is driven by messages that increase confidence in COVID-19 vaccines and perceived behavioral control to get vaccinated. Importantly, messages were particularly effective among more skeptical populations including people who identify as politically conservative or moderate and those who express low trust in government institutions. Our findings corroborate the real-world behavioral significance of vaccination intentions, and devise how even short, scalable online messages can provide governments and health authorities an inexpensive, yet effective tool for increasing intentions to vaccinate against COVID-19 among populations most reluctant to get them.

Fostering participation in digital contact tracing

Digital contact tracing is a promising digital public health intervention to manage epidemics. However, in order to reach its full potential, the technology has to be widely adopted and used. During the SARS-CoV-2 pandemic, this has not necessarily been the case. We review the literature with a focus on how participation in digital contact tracing could be fostered and provide policy recommendations on how to increase its adoption and usage as well as recommendations for further research.

A 680,000-person megastudy of nudges to encourage vaccination in pharmacies

Encouraging vaccination is a pressing policy problem. To assess whether text-based reminders can encourage pharmacy vaccination and what kinds of messages work best, we conducted a megastudy. We randomly assigned 689,693 Walmart pharmacy patients to receive one of 22 different text reminders using a variety of different behavioral science principles to nudge flu vaccination or to a business-as-usual control condition that received no messages. We found that the reminder texts that we tested increased pharmacy vaccination rates by an average of 2.0 percentage points, or 6.8%, over a 3-mo follow-up period. The most-effective messages reminded patients that a flu shot was waiting for them and delivered reminders on multiple days. The top-performing intervention included two texts delivered 3 d apart and communicated to patients that a vaccine was "waiting for you." Neither experts nor lay people anticipated that this would be the best-performing treatment, underscoring the value of simultaneously testing many different nudges in a highly powered megastudy.

Information nudges for influenza vaccination: Evidence from a large-scale cluster-randomized controlled trial in Finland

BACKGROUND

Vaccination is the most effective means of preventing the spread of infectious diseases. Despite the proven benefits of vaccination, vaccine hesitancy keeps many people from getting vaccinated.

METHODS AND FINDINGS

We conducted a large-scale cluster randomized controlled trial in Finland to test the effectiveness of centralized written reminders (distributed via mail) on influenza vaccination coverage. The study included the entire older adult population (aged 65 years and above) in 2 culturally and geographically distinct regions with historically low (31.8%, n = 7,398, mean age 75.5 years) and high (57.7%, n = 40,727, mean age 74.0 years) influenza vaccination coverage. The study population was randomized into 3 treatments: (i) no reminder (only in the region with low vaccination coverage); (ii) an individual-benefits reminder, informing recipients about the individual benefits of vaccination; and (iii) an individual- and social-benefits reminder, informing recipients about the additional social benefits of vaccination in the form of herd immunity. There was no control treatment group in the region with high vaccination coverage as general reminders had been sent in previous years. The primary endpoint was a record of influenza vaccination in the Finnish National Vaccination Register during a 5-month follow-up period (from October 18, 2018 to March 18, 2019). Vaccination coverage after the intervention in the region with historically low coverage was 41.8% in the individual-benefits treatment, 38.9% in the individual- and social-benefits treatment and 34.0% in the control treatment group. Vaccination coverage after the intervention in the region with historically high coverage was 59.0% in the individual-benefits treatment and 59.2% in the individual- and social-benefits treatment. The effect of receiving any type of reminder letter in comparison to control treatment group (no reminder) was 6.4 percentage points (95% CI: 3.6 to 9.1, p < 0.001). The effect of reminders was particularly large among individuals with no prior influenza vaccination (8.8 pp, 95% CI: 6.5 to 11.1, p < 0.001). There was a substantial positive effect (5.3 pp, 95% CI: 2.8 to 7.8, p < 0.001) among the most consistently unvaccinated individuals who had not received any type of vaccine during the 9 years prior to the study. There was no difference in influenza vaccination coverage between the individual-benefit reminder and the individual- and social-benefit reminder (region with low vaccination coverage: 2.9 pp, 95% CI: -0.4 to 6.1, p = 0.087, region with high vaccination coverage: 0.2 pp, 95% CI: -1.0 to 1.3, p = 0.724). Study limitations included potential contamination between the treatments due to information spillovers and the lack of control treatment group in the region with high vaccination coverage.

CONCLUSIONS

In this study, we found that sending reminders was an effective and scalable intervention strategy to increase vaccination coverage in an older adult population with low vaccination coverage. Communicating the social benefits of vaccinations, in addition to individual benefits, did not enhance vaccination coverage. The effectiveness of letter reminders about the benefits of vaccination to improve influenza vaccination coverage may depend on the prior vaccination history of the population.

TRIAL REGISTRATION

AEA RCT registry AEARCTR-0003520 and ClinicalTrials.gov NCT03748160.

Designing and conducting adaptive trials to evaluate interventions in health services and implementation research: practical considerations

Randomized controlled clinical trials are widely considered the gold standard for evaluating the efficacy or effectiveness of interventions in health care. Adaptive trials incorporate changes as the study proceeds, such as modifying allocation probabilities or eliminating treatment arms that are likely to be ineffective. These designs have been widely used in drug discovery studies but can also be useful in health services and implementation research and have been minimally used. As motivating examples, we use an ongoing adaptive trial and two completed parallel group studies and highlight potential advantages, disadvantages, and important considerations when using adaptive trial designs in health services and implementation research. In addition, we investigate the impact on power and the study duration if the two completed parallel-group trials had instead been conducted using adaptive principles. Compared with traditional trial designs, adaptive designs can often allow one to evaluate more interventions, adjust participant allocation probabilities (e.g., to achieve covariate balance), and identify participants who are likely to agree to enroll. These features could reduce resources needed to conduct a trial. However, adaptive trials have potential disadvantages and practical aspects that need to be considered, most notably outcomes that can be rapidly measured and extracted (e.g., long-term outcomes that take significant time to measure from data sources can be challenging), minimal missing data, and time trends. In conclusion, adaptive designs are a promising approach to help identify how best to implement evidence-based interventions into real-world practice in health services and implementation research.

Effect of Nudge-Based Intervention on Adherence to Physician Visit Recommendations and Early Health Outcomes among Individuals Identified with Chronic Kidney Disease in Screens

BACKGROUND

Although CKD screening programs have been provided in many settings, little is known as to how we can effectively translate those screening programs into improved health.

METHODS

We conducted a randomized clinical trial on national health screening for CKD in Japan between April 2018 and March 2019. A total of 4011 participants in CKD screening programs aged 40-63 years were randomly assigned to two interventions or the control, with a ratio of 2:2:1, respectively: (1) the nudge-based letter that contained a message on the basis of behavioral economics, (2) the clinical letter including general information about CKD risks, and (3) the control (informed only of the screening results). The main outcome was adherence to a recommended physician visit within 6 months of the intervention. The secondary outcomes were eGFR, proteinuria, and BP 1 year after the intervention.

RESULTS

Compared with the control group, the probability of undergoing a recommended physician visit was higher among participants who received the nudge-based letter (19.7% for the intervention group versus 15.8% for the control; difference, +3.9 percentage points [pp]; 95% CI, +0.8 to +7.0; P=0.02) and the clinical letter (19.7% versus 15.8%; difference, +3.9 pp; 95% CI, +0.8 to +7.0; P=0.02). We found no evidence that interventions were associated with improved early health outcomes.

CONCLUSIONS

The behavioral economics intervention tested in this large RCT had limited effect on changing behavior or improving health outcomes. Although the approach has promise, this study demonstrates the challenge of developing behavioral interventions that improve the effectiveness of CKD screening programs.Clinical Trial registry name and registration number: University Hospital Medical Information Network Clinical Trial Registry, UMIN000035230.

A meta-analysis of influenza vaccination following correspondence: Considerations for COVID-19

Background

High vaccination rates are needed to protect against influenza and to end the COVID-19 pandemic. Health authorities need to know if supplementing mass communications with direct correspondence to the community would increase uptake.

Objectives

The primary objective is to determine if sending a single written message directly to individuals increases influenza vaccine uptake, and a secondary objective is to identify any identified content shown to increase influenza vaccine uptake.

Methods

MEDLINE, Embase, Cochrane CENTRAL, PsycINFO, and PubMed were searched for RCTs testing a single correspondence for members of the community in OECD countries to obtain influenza vaccination. A meta-analysis with inverse-variance, random-effects modelling was used to estimate a mean, weighted risk ratio effect size measure of vaccine uptake. Studies were quality assessed and analysis was undertaken to account for potential publication bias.

Results

Twenty-eight randomized controlled trials were included, covering 45 interventions. Of the 45 interventions, 37 (82.2%) report an increase in influenza vaccination rates. A formal meta-analysis shows that sending a single written message increased influenza vaccine uptake by 16%, relative to the no contact comparator group (RR = 1.16, 95% CI [1.13-1.20], Z = 9.25, p < .001). Analysis shows that the intervention is effective across correspondence type, age group, time, and location, and after allowing for risk of publication bias.

Limitations

The generalizability of results across the OECD may be questioned.

Conclusions and implications

The implication for public health authorities organizing vaccination programs for influenza, and arguably also for COVID-19, is that sending written vaccination correspondence to members of the community is likely to increase uptake. Keywords: vaccine uptake, COVID-19, influenza, direct correspondence, meta-analysis.

This study is pre-registered on osf.io; details can be found at https://osf.io/98mr7

Improving postal survey response using behavioural science: a nested randomised control trial

Background

Systematic reviews have identified effective strategies for increasing postal response rates to questionnaires; however, most studies have isolated single techniques, testing the effect of each one individually. Despite providing insight into explanatory mechanisms, this approach lacks ecological validity, given that multiple techniques are often combined in routine practice.

Methods

We used a two-armed parallel randomised controlled trial (n = 2702), nested within a cross-sectional health survey study, to evaluate whether using a pragmatic combination of behavioural science and evidenced-based techniques (e.g., personalisation, social norms messaging) in a study invitation letter increased response to the survey, when compared with a standard invitation letter. Participants and outcome assessors were blinded to group assignment. We tested this in a sample of women testing positive for human papillomavirus (HPV) at cervical cancer screening in England.

Results

Overall, 646 participants responded to the survey (response rate [RR] = 23.9%). Logistic regression revealed higher odds of response in the intervention arm (n = 357/1353, RR = 26.4%) compared with the control arm (n = 289/1349, RR = 21.4%), while adjusting for age, deprivation, clinical site, and clinical test result (aOR = 1.30, 95% CI: 1.09–1.55).

Conclusion

Applying easy-to-implement behavioural science and evidence-based methods to routine invitation letters improved postal response to a health-related survey, whilst adjusting for demographic characteristics. Our findings provide support for the pragmatic adoption of combined techniques in routine research to increase response to postal surveys.

Trial registration

ISRCTN, ISRCTN15113095. Registered 7 May 2019 – retrospectively registered.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12874-021-01476-7.

REinforcement learning to improve non-adherence for diabetes treatments by Optimising Response and Customising Engagement (REINFORCE): study protocol of a pragmatic randomised trial

INTRODUCTION

Achieving optimal diabetes control requires several daily self-management behaviours, especially adherence to medication. Evidence supports the use of text messages to support adherence, but there remains much opportunity to improve their effectiveness. One key limitation is that message content has been generic. By contrast, reinforcement learning is a machine learning method that can be used to identify individuals' patterns of responsiveness by observing their response to cues and then optimising them accordingly. Despite its demonstrated benefits outside of healthcare, its application to tailoring communication for patients has received limited attention. The objective of this trial is to test the impact of a reinforcement learning-based text messaging programme on adherence to medication for patients with type 2 diabetes.

METHODS AND ANALYSIS

In the REinforcement learning to Improve Non-adherence For diabetes treatments by Optimising Response and Customising Engagement (REINFORCE) trial, we are randomising 60 patients with suboptimal diabetes control treated with oral diabetes medications to receive a reinforcement learning intervention or control. Subjects in both arms will receive electronic pill bottles to use, and those in the intervention arm will receive up to daily text messages. The messages will be individually adapted using a reinforcement learning prediction algorithm based on daily adherence measurements from the pill bottles. The trial's primary outcome is average adherence to medication over the 6-month follow-up period. Secondary outcomes include diabetes control, measured by glycated haemoglobin A1c, and self-reported adherence. In sum, the REINFORCE trial will evaluate the effect of personalising the framing of text messages for patients to support medication adherence and provide insight into how this could be adapted at scale to improve other self-management interventions.

ETHICS AND DISSEMINATION

This study was approved by the Mass General Brigham Institutional Review Board (IRB) (USA). Findings will be disseminated through peer-reviewed journals, clinicaltrials.gov reporting and conferences.

TRIAL REGISTRATION NUMBER

Clinicaltrials.gov (NCT04473326).

A message of the majority with scientific evidence encourages young people to show their prosocial nature in COVID-19 vaccination

The most promising way to prevent the explosive spread of COVID-19 infection is to achieve herd immunity through vaccination. It is therefore important to motivate those who are less willing to be vaccinated. To address this issue, we conducted an online survey of 6232 Japanese people to investigate age- and gender-dependent differences in attitudes towards COVID-19 vaccination and the underlying psychological processes. We asked participants to read one of nine different messages about COVID-19 vaccination and rate their willingness to be vaccinated. We also collected their 17 social personality trait scores and demographic information. We found that males 10-20 years old were least willing to be vaccinated. We also found that prosocial traits are the driving force for young people, but the motivation in older people also depends on risk aversion and self-interest. Furthermore, an analysis of 9 different messages demonstrated that for young people (particularly males), the message emphasizing the majority's intention to vaccinate and scientific evidence for the safety of the vaccination had the strongest positive effect on the willingness to be vaccinated, suggesting that the "majority + scientific evidence" message nudges young people to show their prosocial nature in action.

Emphasize personal health benefits to boost COVID-19 vaccination rates

The rapid development of COVID-19 vaccines is a tremendous scientific response to the current global pandemic. However, vaccines per se do not save lives and restart economies. Their success depends on the number of people getting vaccinated. We used a survey experiment to examine the impact on vaccine intentions of a variety of public health messages identified as particularly promising: three messages that emphasize different benefits from the vaccines (personal health, the health of others, and the recovery of local and national economies) and one message that emphasizes vaccine safety. Because people will likely be exposed to multiple messages in the real world, we also examined the effect of these messages in combination. Based on a nationally quota representative sample of 3,048 adults in the United States, our findings suggest that several forms of public messages can increase vaccine intentions, but messaging that emphasizes personal health benefits had the largest impact.

The role of health determinants in the influenza vaccination uptake among older adults (65+): a scope review

Background

Although the burden of influenza infection is the highest in older adults, vaccination coverage remains low, despite this age group being more vulnerable than others.

Aims

Given the current pandemic of SARS-CoV-2, it was the aim of this scope review to update knowledge on factors affecting seasonal influenza vaccine uptake among older adults to strengthen prevention approaches in the context of an overall burden of infectious diseases.

Methods

We searched bibliographic databases from 2012 to 2019. All studies reviewed one or more social determinant of health listed by WHO, or factors affecting the decision-making process whether to accept influenza vaccine or not.

Results

Overall, 44 studies were included, 41 determinants were extracted and summarized into six categories. Older age and constitutional factors including multiple chronic diseases as well as preventive lifestyle and frequent routine healthcare utilization positively affected vaccination uptake (VU). Living and working conditions are also researched determinants of influenza vaccine uptake. A small number of studies explored the role of social inclusion and system-based interventions.

Discussion and conclusions

This scope review provides a comprehensive overview on factors affecting seasonal influenza vaccination uptake among older citizens. The review also clearly shows gaps for evidence on system-based level or political strategies to improve vaccination uptake.

Supplementary Information

The online version contains supplementary material available at 10.1007/s40520-021-01793-3.

A megastudy of text-based nudges encouraging patients to get vaccinated at an upcoming doctor's appointment

Many Americans fail to get life-saving vaccines each year, and the availability of a vaccine for COVID-19 makes the challenge of encouraging vaccination more urgent than ever. We present a large field experiment (N = 47,306) testing 19 nudges delivered to patients via text message and designed to boost adoption of the influenza vaccine. Our findings suggest that text messages sent prior to a primary care visit can boost vaccination rates by an average of 5%. Overall, interventions performed better when they were 1) framed as reminders to get flu shots that were already reserved for the patient and 2) congruent with the sort of communications patients expected to receive from their healthcare provider (i.e., not surprising, casual, or interactive). The best-performing intervention in our study reminded patients twice to get their flu shot at their upcoming doctor's appointment and indicated it was reserved for them. This successful script could be used as a template for campaigns to encourage the adoption of life-saving vaccines, including against COVID-19.

Informing patients that they are at high risk for serious complications of viral infection increases vaccination rates

For many vaccine-preventable diseases like influenza, vaccination rates are lower than optimal to achieve community protection. Those at high risk for infection and serious complications are especially advised to be vaccinated to protect themselves. Using influenza as a model, we studied one method of increasing vaccine uptake: informing high-risk patients, identified by a machine learning model, about their risk status. Patients (N=39,717) were evenly randomized to (1) a control condition (exposure only to standard direct mail or patient portal vaccine promotion efforts) or to be told via direct mail, patient portal, and/or SMS that they were (2) at high risk for influenza and its complications if not vaccinated; (3) at high risk according to a review of their medical records; or (4) at high risk according to a computer algorithm analysis of their medical records. Patients in the three treatment conditions were 5.7% more likely to get vaccinated during the 112 days post-intervention (p < .001), and did so 1.4 days earlier (p < .001), on average, than those in the control group. There were no significant differences among risk messages, suggesting that patients are neither especially averse to nor uniquely appreciative of learning their records had been reviewed or that computer algorithms were involved. Similar approaches should be considered for COVID-19 vaccination campaigns.

Rationale and design of the Novel Uses of adaptive Designs to Guide provider Engagement in Electronic Health Records (NUDGE-EHR) pragmatic adaptive randomized trial: a trial protocol

BACKGROUND

The prescribing of high-risk medications to older adults remains extremely common and results in potentially avoidable health consequences. Efforts to reduce prescribing have had limited success, in part because they have been sub-optimally timed, poorly designed, or not provided actionable information. Electronic health record (EHR)-based tools are commonly used but have had limited application in facilitating deprescribing in older adults. The objective is to determine whether designing EHR tools using behavioral science principles reduces inappropriate prescribing and clinical outcomes in older adults.

METHODS

The Novel Uses of Designs to Guide provider Engagement in Electronic Health Records (NUDGE-EHR) project uses a two-stage, 16-arm adaptive randomized pragmatic trial with a "pick-the-winner" design to identify the most effective of many potential EHR tools among primary care providers and their patients ≥ 65 years chronically using benzodiazepines, sedative hypnotic ("Z-drugs"), or anticholinergics in a large integrated delivery system. In stage 1, we randomized providers and their patients to usual care (n = 81 providers) or one of 15 EHR tools (n = 8 providers per arm) designed using behavioral principles including salience, choice architecture, or defaulting. After 6 months of follow-up, we will rank order the arms based upon their impact on the trial's primary outcome (for both stages): reduction in inappropriate prescribing (via discontinuation or tapering). In stage 2, we will randomize (a) stage 1 usual care providers in a 1:1 ratio to one of the up to 5 most promising stage 1 interventions or continue usual care and (b) stage 1 providers in the unselected arms in a 1:1 ratio to one of the 5 most promising interventions or usual care. Secondary and tertiary outcomes include quantities of medication prescribed and utilized and clinically significant adverse outcomes.

DISCUSSION

Stage 1 launched in October 2020. We plan to complete stage 2 follow-up in December 2021. These results will advance understanding about how behavioral science can optimize EHR decision support to improve prescribing and health outcomes. Adaptive trials have rarely been used in implementation science, so these findings also provide insight into how trials in this field could be more efficiently conducted.

TRIAL REGISTRATION

Clinicaltrials.gov ( NCT04284553 , registered: February 26, 2020).

Attractive Flu Shot: A Behavioral Approach to Increasing Influenza Vaccination Uptake Rates

Background. We suggest and examine a behavioral approach to increasing seasonal influenza vaccine uptake. Our idea combines behavioral effects generated by a dominated option, together with more traditional tools, such as providing information and recommendations. Methods. Making use of the seasonal nature of the flu, our treatments present participants with 2 options to receive the shot: early in the season, which is recommended and hence "attractive," or later. Three additional layers are examined: 1) mentioning that the vaccine is more likely to run out of stock late in the season, 2) the early shot is free while the late one costs a fee, and 3) the early shot carries a monetary benefit. We compare vaccination intentions in these treatments to those of a control group who were invited to receive the shot regardless of timing. Results. Using a sample of the Israeli adult population (n = 3271), we found positive effects of all treatments on vaccination intentions, and these effects were significant for 3 of the 4 treatments. In addition, the vast majority of those who are willing to vaccinate intend to get the early shot. Conclusions. Introducing 2 options to get vaccinated against influenza (early or late) positively affects intentions to receive the flu shot. In addition, this approach nudges participants to take the shot in early winter, a timing that has been shown to be more cost-effective.

Close contact behavior in indoor environment and transmission of respiratory infection

Close contact was first identified as the primary route of transmission for most respiratory infections in the early 20th century. In this review, we synthesize the existing understanding of the mechanisms of close contact transmission. We focus on two issues: the mechanism of transmission in close contact, namely the transmission of the expired particles between two people, and the physical parameters of close contact that affect the exposure of particles from one individual to another, or how the nature of close contact plays a role in transmission. We propose the existence of three sub-routes of transmission: short-range airborne, large droplets, and immediate body-surface contact. We also distinguish a "body contact," which is defined with an interpersonal distance of zero, from a close contact. We demonstrate herein that the short-range airborne sub-route may be most common. The timescales over which data should be collected to assess the transmission risk during close contact events are much shorter than those required for the distant airborne or fomite routes. The current paucity of high-resolution data over short distances and timescales makes it very difficult to assess the risk of infection in these circumstances.

Hand-Hygiene Mitigation Strategies Against Global Disease Spreading through the Air Transportation Network

The risk for a global transmission of flu-type viruses is strengthened by the physical contact between humans and accelerated through individual mobility patterns. The Air Transportation System plays a critical role in such transmissions because it is responsible for fast and long-range human travel, while its building components-the airports-are crowded, confined areas with usually poor hygiene. Centers for Disease Control and Prevention (CDC) and World Health Organization (WHO) consider hand hygiene as the most efficient and cost-effective way to limit disease propagation. Results from clinical studies reveal the effect of hand washing on individual transmissibility of infectious diseases. However, its potential as a mitigation strategy against the global risk for a pandemic has not been fully explored. Here, we use epidemiological modeling and data-driven simulations to elucidate the role of individual engagement with hand hygiene inside airports in conjunction with human travel on the global spread of epidemics. We find that, by increasing travelers engagement with hand hygiene at all airports, a potential pandemic can be inhibited by 24% to 69%. In addition, we identify 10 airports at the core of a cost-optimal deployment of the hand-washing mitigation strategy. Increasing hand-washing rate at only those 10 influential locations, the risk of a pandemic could potentially drop by up to 37%. Our results provide evidence for the effectiveness of hand hygiene in airports on the global spread of infections that could shape the way public-health policy is implemented with respect to the overall objective of mitigating potential population health crises.

Randomised controlled trial of a theory-based intervention to prompt front-line staff to take up the seasonal influenza vaccine

OBJECTIVE

To evaluate the effectiveness of reminder letters informed by social normative theory (a type of 'nudge theory') on uptake of seasonal influenza vaccination by front-line hospital staff.

DESIGN

Individually randomised controlled trial.

SETTING

A large acute care hospital in England.

PARTICIPANTS

Front-line staff employed by the hospital (n=7540) were randomly allocated to one of four reminder types in a factorial design.

INTERVENTIONS

The standard letter included only general information directing the staff to take up the vaccine. A second letter highlighted a type of social norm based on peer comparisons. A third letter highlighted a type of social norm based on an appeal to authority. A fourth letter included a combination of the social norms.

MAIN OUTCOME MEASURE

The proportion of hospital staff vaccinated on-site.

RESULTS

Vaccine coverage was 43% (812/1885) in the standard letter group, 43% (818/1885) in the descriptive norms group, 43% (814/1885) in the injunctive norms group and 43% (812/1885) in the combination group. There were no statistically significant effects of either norm or the interaction. The OR for the descriptive norms factor is 1.01 (0.89-1.15) in the absence of the injunctive norms factor and 1.00 (0.88-1.13) in its presence. The OR for the injunctive norms factor is 1.00 (0.88-1.14) in the absence of the descriptive norms factor and 0.99 (0.87-1.12) in its presence.

CONCLUSIONS

We find no evidence that the uptake of the seasonal influenza vaccination is affected by reminders using social norms to motivate uptake.

Randomised controlled trial of a theory-based intervention to prompt front-line staff to take up the seasonal influenza vaccine

Objective

To evaluate the effectiveness of reminder letters informed by social normative theory (a type of ‘nudge theory’) on uptake of seasonal influenza vaccination by front-line hospital staff.

Design

Individually randomised controlled trial.

Setting

A large acute care hospital in England.

Participants

Front-line staff employed by the hospital (n=7540) were randomly allocated to one of four reminder types in a factorial design.

Interventions

The standard letter included only general information directing the staff to take up the vaccine. A second letter highlighted a type of social norm based on peer comparisons. A third letter highlighted a type of social norm based on an appeal to authority. A fourth letter included a combination of the social norms.

Main outcome measure

The proportion of hospital staff vaccinated on-site.

Results

Vaccine coverage was 43% (812/1885) in the standard letter group, 43% (818/1885) in the descriptive norms group, 43% (814/1885) in the injunctive norms group and 43% (812/1885) in the combination group. There were no statistically significant effects of either norm or the interaction. The OR for the descriptive norms factor is 1.01 (0.89–1.15) in the absence of the injunctive norms factor and 1.00 (0.88–1.13) in its presence. The OR for the injunctive norms factor is 1.00 (0.88–1.14) in the absence of the descriptive norms factor and 0.99 (0.87–1.12) in its presence.

Conclusions

We find no evidence that the uptake of the seasonal influenza vaccination is affected by reminders using social norms to motivate uptake.