Do the vaccinated perform less distancing, mask wearing and hand hygiene? A test of the risk compensation hypothesis in a representative sample during the COVID-19 pandemic

Investigating the causal effects of COVID-19 vaccination on the adoption of protective behaviors in Japan: Insights from a fuzzy regression discontinuity design

BACKGROUND

During the COVID-19 pandemic, concerns emerged that vaccinated individuals might engage less in infection-preventive behaviors, potentially contributing to virus transmission. This study evaluates the causal effects of COVID-19 vaccination on such behaviors within Japan, highlighting the significance of understanding behavioral dynamics in public health strategies.

METHODS

Utilizing Japan's age-based vaccination priority for those born before April 1, 1957, this research employs a regression discontinuity design (RDD) to assess the vaccination's impact. Data from the fourth round of a longitudinal online survey, conducted from July 20 to 27, 2021, served as the basis for analyzing 14 infection-protective behaviors, including mask usage, handwashing, and avoiding crowds.

RESULTS

A total of 12067 participants completed the survey. The analyzed sample size varied by outcome variable, ranging from 1499 to 5233. The analysis revealed no significant differences in the 14 behaviors examined among fully vaccinated, partially vaccinated, and unvaccinated individuals. This consistency across groups suggests that vaccination status did not significantly alter engagement in protective behaviors during the observation period.

CONCLUSIONS

Empirical findings highlight the complexity of behavioral responses following vaccination, indicating that such responses may be influenced by various factors, rather than by vaccination status alone. Additionally, this result underscores the importance of crafting public health policies that account for the intricate interplay between vaccination and behavior. This study contributes to the broader discourse on managing responses to the pandemic and tailoring interventions to sustain or enhance protective health behaviors amid vaccination rollouts.

Is badger culling associated with risk compensation behaviour among cattle farmers?

BACKGROUND

Risk compensation theory suggests that behaviours are modified in response to interventions that remove risks by substituting them with other risky behaviours to maintain a 'risk equilibrium'. Alternatively, risk reduction interventions may result in spill-over behaviours that seek to minimise risks further. This paper assessed evidence for these behavioural risk responses among farmers in response to badger culling that seeks to remove the risk of bovine tuberculosis in cattle.

METHODS

Data from the UK's randomised badger culling trial were re-analysed, comparing farmers' cattle movement practices in proactive and reactive culling areas and control areas. Analysis compared cattle movements during and after the trial using zero-inflated negative binomial regression.

RESULTS

The analysis found no strong evidence of risk compensation behaviours among farmers who experienced proactive culling. However, strong evidence for a reduction in cattle movements in reactive culling areas was found. The results indicate high levels of inertia within farming systems in relation to cattle purchasing.

LIMITATIONS

Data do not account for the risk of cattle purchases and reflect previous policy regimens. Evidence from recent badger culling interventions should be analysed.

CONCLUSION

Proactive badger culling was not associated with risk compensation behaviours, while reactive badger culling was associated with decreased risk taking among farmers.

Perception of interpersonal distance and social distancing before and during COVID-19 pandemic

Since COVID-19 is easily transmitted among people in close physical proximity, the focus of epidemiological policy during the COVID-19 crisis included major restrictions on interpersonal distance. However, the way in which distance restrictions affected spatial perception is unclear. In the current study, we examined interpersonal distance preferences and perceptions at three time points: pre-pandemic, early post-pandemic, and late post-pandemic. The results indicate that following the pandemic outbreak, people perceived others as farther away than they actually were, suggesting that the distance restrictions were associated with an enlargement of perceived interpersonal distance. Interestingly, however, people maintained the same distance from one another as before the outbreak, indicating no change in actual distance behavior due to the risk of infection. These findings suggest that COVID-19 was associated with a change in the way distance is perceived, while in practice, people maintain the same distance as before. In contrast, COVID-related anxiety predicted both a preference for maintaining a greater distance and a bias toward underestimating perceived distance from others. Thus, individuals who were highly fearful of COVID-19 perceived other people to be closer than they actually were and preferred to maintain a larger distance from them. The results suggest that subjective risk can lead to an increased perception of danger and a subsequent change in behavior. Taken together, even when behaviors should logically change, the decision-making process can be based on distorted perceptions. This insight may be used to predict public compliance.

Does the COVID-19 Vaccination Reduce the Risk to Transmit SARS-CoV-2 to Others?

It has been assumed that the COVID-19 vaccination reduces the risk of transmission to others. Results during the delta predominance show that the viral load in the vaccinated population is not consistently lower compared to the unvaccinated, and during the omicron predominance, the viral load was even somewhat higher. Levels of infectious SARS-CoV-2 were partly lower in the vaccinated population. Viral loads were mostly lower in re-infections compared to breakthrough infections. Viral clearance including the detection of infectious virus has mostly been described to be faster in the vaccinated population suggesting a shorter duration as a possible source for transmission. The epidemiological relevance of this finding remains uncertain. Approximately half of the transmission studies found lower secondary attack rates from the fully vaccinated population, but the results are probably best explained by the vaccination status of the contact population. Public health data from the UK show that the number of COVID-19 cases is higher among the fully vaccinated and boosted population who might be possible sources, in contrast to lower case numbers within the first three months among the vaccinated obtained in phase 3 trials on symptomatic cases. Overall, there is no convincing evidence that the COVID-19 vaccination significantly reduces the risk to transmit SARS-CoV-2 to others.

Health Behaviours among Travellers Regarding Risk Compensation Following COVID-19 Vaccination in Taizhou, China

Background

During the COVID-19 pandemic, public transport was restricted in many countries because of the transmission risk. According to the risk compensation theory, travellers post-COVID-19 vaccination may encounter higher risks; however, no real-world studies provide such evidence. Therefore, we conducted a survey to assess whether risk compensation would occur among travellers' health-related behaviours after COVID-19 vaccination, potentially aggravating the transmission of the virus.

Materials and Methods

A self-administered online survey was designed and distributed over WeChat to identify the difference in health behaviours before and after COVID-19 vaccination among travellers at a train station in Taizhou, China, from 13 February to 26 April 2022.

Results

A total of 602 individuals completed the questionnaire. The results revealed no statistical difference between the health behaviours reported by the vaccinated and unvaccinated groups. Participants who received the first dose of the vaccine earlier showed no statistical difference in harmful health behaviours (hand washing frequency decreased by 4.1% (P=0.145) and the duration of public transport travel increased by 3.4% (P=0.437)), but showed better protective health behaviours (mask-wearing duration increased by 24.7% (P=0.014)). Compared to those vaccinated less than three times, participants vaccinated against COVID-19 three times showed no statistical differences in harmful health behaviours mask-wearing duration decreased by 7.0% (P=0.927), their hand washing frequency decreased by 4.8% (P=0.905), and the duration of public transport travel increased by 2.5% (P=0.287). After vaccination, when compared to themselves before vaccination, participants exhibited better health behaviours (increased hand washing frequency and mask-wearing duration, and decreased duration of public transport travel) to some extent.

Conclusion

In conclusion, this study found no evidence of risk compensation among travellers. After being vaccinated, health behaviours partly improved among travellers.

Social cognitive predictors of vaccination status, uptake and mitigation behaviors in the Canadian COVID-19 Experiences survey

Emerging infectious diseases like COVID-19 will remain a concern for the foreseeable future, and determinants of vaccination and other mitigation behaviors are therefore critical to understand. Using data from the first two waves of the Canadian COVID-19 Experiences Survey (CCES; N = 1,958; 66.56 % female), we examined social cognitive predictors of vaccination status, transition to acceptance and mitigation behaviors in a population-representative sample. Findings indicated that all social cognitive variables were strong predictors of mitigation behavior performance at each wave, particularly among unvaccinated individuals. Among those who were vaccine hesitant at baseline, most social cognitive variables predicted transition to fully vaccinated status at follow-up. After controlling for demographic factors and geographic region, greater odds of transitioning from unvaccinated at CCES Wave 1 to fully vaccinated at CCES Wave 2 was predicted most strongly by a perception that one's valued peers were taking up the vaccine (e.g., dynamic norms (OR = 2.13 (CI: 1.54,2.93)), perceived effectiveness of the vaccine (OR = 3.71 (CI: 2.43,5.66)), favorable attitudes toward the vaccine (OR = 2.80 (CI: 1.99,3.95)), greater perceived severity of COVID-19 (OR = 2.02 (CI: 1.42,2.86)), and stronger behavioral intention to become vaccinated (OR = 2.99 (CI: 2.16,4.14)). As a group, social cognitive variables improved prediction of COVID-19 mitigation behaviors (masking, distancing, hand hygiene) by a factor of 5 compared to demographic factors, and improved prediction of vaccination status by a factor of nearly 20. Social cognitive processes appear to be important leverage points for health communications to encourage COVID-19 vaccination and other mitigation behaviors, particularly among initially hesitant members of the general population.