Perceptions and responses to COVID-19 through wastewater surveillance information and online search behavior: A randomized controlled trial (preprint)

Wastewater surveillance is anticipated to be a representative and timely method to assess infectious disease status; however, its influence on public perception and behavior remains unclear. Therefore, in this study, we used a randomized controlled trial to analyze the influence of wastewater surveillance-based information on understanding of, interest in, relief regarding, preventive behavioral intention against, and subsequent online search behavior related to coronavirus disease 2019 (COVID-19). Valid responses were obtained from 1,000 individuals in both control and intervention groups from Yahoo crowdsourcing users aged [≥]18 years in Japan. This survey was conducted from August 4 to August 7, 2023, just before the common Japanese tradition of returning to hometowns. The questionnaire not only collected personal attributes but also gauged responses to COVID-19 information. This information highlighted the early detection capabilities and representativeness of wastewater surveillance compared with sentinel surveillance at medical institutions. At one-week post-survey, we obtained the survey participants' online search history for key words such as "bullet train," "highway," "airplane," and "wastewater." The findings showed no significant differences between the two groups in terms of COVID-19 interest or preventive behavior before information provision, verifying the effectiveness of participant randomization. Wastewater surveillance-based information did not notably elevate understanding or specific intentions regarding COVID-19, such as wearing masks and receiving vaccination. However, it significantly increased interest in, relief concerning the infection status, and general preventive behavioral intentions. Heightened interest and general preventive intentions did not depend on prior interest or behavior. However, those who previously engaged in preventive behavior or who were less interested in COVID-19 exhibited more relief after exposure to wastewater surveillance-based information. Furthermore, this information could slightly influence online searches related to return travel modes, such as highways. In conclusion, information from wastewater surveillance effectively shapes individual perceptions of and responses to infections.

Psychotherapies and Psychological Support for Individuals Facing Psychological Distress during the COVID-19 Pandemic: A Scoping Review (preprint)

In this scoping review, we investigated psychotherapies and psychological support provided during the coronavirus disease 2019 (COVID-19) pandemic to clarify its recipients and the methods employed. We used Scopus and PubMed as the search engines on October 18, 2022, employing specific search terms (''COVID* '' AND (''Psychotherap*'' OR ''psychological support*'') AND ''psychological distress*''). The initial search yielded 153 articles, of which 18 met the eligibility criteria after two rounds of screening. The distribution of participants ranged from the general population to patients with COVID-19 and those who had recovered. However, no studies of patients with post-COVID-19 sequelae were found. The distribution of the types of psychotherapies and psychological support varied and the use of new technology was suggested. Online interventions comprised the majority of the means of psychotherapies and psychological support. This study suggests that psychotherapies and psychological support during the COVID-19 pandemic were influenced by the social situation.

Bi-directional associations between mask usage and the associated reasons before and after the downgrading of the legal status of COVID-19 in Japan: A longitudinal study (preprint)

ObjectivesFrom a public health perspective, it is important to clarify the associations between mask usage and the associated reasons in situations when mask usage is promoted or mitigated. Therefore, I clarified the changes in mask usage and the associated reasons before and after the downgrading of the legal status of COVID-19 in Japan, and analyzed the bi-directional associations between the two. DesignLongitudinal study. MethodsOnline surveys were conducted in two waves, between April 18-19, 2023 and June 6-15, 2023, among people aged 20-69 years living in Japan. A total of 291 participants completed both the surveys. The associations between mask usage and beliefs about the reasons for mask usage were analyzed using a cross-lagged panel model. ResultsMask usage decreased slightly, but significantly, from the first to the second wave (P < 0.001, Cohens d = -0.23). Of the eight beliefs regarding mask usage, slight but significant decreases were observed in terms of relief and information effects (P = 0.046, Cohens d = -0.12; P = 0.018, Cohens d = -0.14). There was a significant association between socio-psychological reasons other than infection risk avoidance (such as norm and relief) during the first wave and mask usage during the second wave [standard estimates:0.25 (95% confidence interval (CI):0.06-0.44)]. Contrarily, mask usage during the first wave was significantly associated with the reasons for infection risk avoidance during the second wave [standard estimates:0.13 (0.03-0.24)]. ConclusionsThe impact of downgrading the legal status of COVID-19 in Japan on mask usage and the associated reasons were found to be limited. In terms of promoting or mitigating mask usage, the significance of risk communication based on socio-psychological reasons other than infection risk avoidance, such as norms and relief, was highlighted.

Exploratory Study to Characterise the Individual Types of Health Literacy and Beliefs and Their Associations with Infection Prevention Behaviours amid the COVID-19 Pandemic in Japan: A Longitudinal Study (preprint)

Background. During a global infectious disease pandemic such as the coronavirus disease 2019 (COVID-19), individuals' infection prevention/risk-taking behaviours are likely to differ depending on their health literacy and beliefs regarding the disease. To effectively promote infection prevention behaviours, it is necessary to enable information dissemination and risk communication that consider individuals' health literacy and beliefs. In this study, we exploratorily characterised segments based on individual health literacy and beliefs regarding COVID-19 among the Japanese during the early stage of the COVID-19 pandemic, and investigated whether infection prevention/risk-taking behaviours and fear of COVID-19 differed among these segments. Methods. In this study, we conducted two web-based longitudinal surveys in Japan (PHASE 1, 1-30 November 2020, 6,000 participants; PHASE 2, 1-31 December 2020, 3,800 participants). We characterised segments of the target population using cluster analysis on health literacy and beliefs regarding COVID-19 obtained in PHASE 1. We further investigated the associations between the clusters and infection prevention/risk-taking behaviours and fear of COVID-19, obtained from PHASE 2. Results. Five clusters were identified: 'Calm/hoax denial', 'Hoax affinity/threat denial', 'Minority/indifference', 'Over vigilance', and 'Optimism'. There were significant differences in infection prevention/risk-taking behaviours and fear of COVID-19 among the five clusters. The belief in susceptibility to infection, rather than affinity for hoaxes and conspiracy theories, was coherently associated with infection prevention/risk-taking behaviours and fear of infection across clusters. This study provides foundational knowledge for creating segment-specific public messages and developing interactive risk communication to encourage infection prevention behaviours.

Effects of inbound attendees of a mass gathering event on the COVID-19 epidemic using individual-based simulations (preprint)

Given that mass gathering events involve heterogeneous and time-varying contact between residents and visitors, we sought to identify possible measures to prevent the potential acceleration of the outbreak of an emerging infectious disease induced by such events. An individual-based simulator was built based on a description of the reproduction rate among people infected with the infectious disease in a hypothetical city. Three different scenarios were assessed using our simulator, in which controls aimed at reduced contact were assumed to be carried out only in the main event venue or at subsequent additional events, or in which behavior restrictions were carried out among the visitors to the main event. The simulation results indicated that the increase in the number of patients with COVID-19 could possibly be suppressed to a level equivalent to that if the event were not being held so long as the prevalence among visitors was only slightly higher than that among domestic residents and strict requirements were applied to the activities of visitors.

Sensitivity of rapid antigen tests for COVID-19 during the Omicron variant outbreak (preprint)

Background Rapid antigen tests have been used to prevent the spread of the coronavirus disease 2019 (COVID-19); however, there have been concerns about their decreased sensitivity to the Omicron variant. Aims In this study, we compared the sensitivity and specificity of the rapid antigen and the polymerase chain reaction (PCR) tests among the players and staff members of the Japan Professional Football League and clubs. Furthermore, we evaluated the relationship between the sensitivity and the duration from the onset of the symptoms to testing, the manufacturer of the rapid antigen test kits, and the PCR test analyte. Design and methods This was a retrospective observational study. We used 656 results from both the rapid antigen and PCR tests for COVID-19 using the analytes collected on the same day from January 12 to March 2, 2022, during the Omicron variant outbreak in Japan. Results The sensitivity of the rapid antigen test compared with the PCR test was 0.63 (95% confidence interval: 0.54–0.72) and the specificity was 0.998 (95% confidence interval: 0.995–1.000). There were no significant associations between the sensitivity and the duration from the onset of the symptoms to testing (including asymptomatic cases in the category), vaccination status, manufacturer of the rapid antigen test kit or PCR analyte ( P > 0.05) with small effect sizes (Cramer’s V or φ: ≤ 0.22). Conclusions Even during the Omicron outbreak, the sensitivity of the rapid antigen tests did not depend on the duration from the onset of the symptoms to testing.

Annual prevalence of non-communicable diseases and identification of vulnerable populations following the Fukushima disaster and COVID-19 pandemic (preprint)

Disasters, pandemics, and their response measures can have secondary effects on the physical and psychological health of affected populations. Identifying populations vulnerable to these effects is beneficial for promoting effective health and prevention strategies. Using health insurance receipt data from 2009 to 2020, we assessed changes in prevalence of major non-communicable diseases (NCDs), including hypertension, hyperlipidemia, diabetes, and mental disorders, among affected populations before and after the Fukushima disaster and coronavirus disease (COVID-19) outbreak in Japan. Furthermore, age and sex groups with the largest increases in prevalence after these events were identified. The participants of this study were members of the Employees' Health Insurance scheme, including employees of companies and their dependent family members. The dataset was provided by JMDC Inc. The annual age-adjusted prevalence of each disease was used to calculate the ratio of disease prevalence before and after the events. After the Fukushima disaster, hypertension, hyperlipidemia, and diabetes generally increased over a 9-year period in Fukushima Prefecture. The increase in the prevalence rate of these three NCDs and mental disorders were the highest among females aged 40-74 years compared to males and the other age groups. The prevalence of all four diseases increased after the COVID-19 outbreak in Japan, with marked increase in males aged 0-39 years. Populations that have experienced secondary health effects such as NCDs are unique to each disaster or pandemic, and it is important to provide tailor-made public health support among populations in accordance to the type of disasters and pandemic.

Development of a COVID-19 risk-assessment model for participants at an outdoor music festival: Evaluation of the validity and control measure effectiveness (preprint)

We developed an environmental exposure model to estimate the Coronavirus Disease 2019 (COVID-19) risk among participants at an outdoor music festival and validated the model using a real cluster outbreak case. Furthermore, we evaluated the extent to which the risk could be reduced by additional infection control measures such as negative proofs of antigen tests on the day of the event, wearing masks, disinfection of environmental surfaces, and vaccination. The total number of already- and newly-infected individuals who participated in the event according to the new model was 47.0 (95% uncertainty interval: 12.5-185.5), which is in good agreement with the reported value (45). Among the additional control measures, vaccination, mask-wearing, and disinfection of surfaces were determined to be effective. Based on the combination of all measures, a 94% risk reduction could be achieved. In addition to setting a benchmark for an acceptable number of newly-infected individuals at the time of an event, the application of this model will enable us to determine whether it is necessary to implement additional measures, limit the number of participants, or refrain from holding an event.

Quantifying the effect of isolation and negative certification on COVID-19 transmission (preprint)

Background: Isolation of close contact people and negative test certification are used to manage the spread of new coronavirus infections worldwide. These effectively prevent the spread of infection in advance, but they can lead to a decline in socio-economic activity. Thus, the present study quantified the extent to which isolation and negative test certification respectively reduce the risk of infection. Methods: A discrete-time SEIR model was used as the infectious disease model, and equations for calculating the conditional probability of non-infection status given negative test results on two different days were derived. Results: The respective non-infection probabilities with two negative PCR test results, and with one negative PCR test result and one antigen test result, were quantified. By substituting initial parameters of the SEIR model into these probabilities, the present study revealed the following: (1) isolating close contact individuals can reduce by 80% the risk of infection during the first five days, but five more days are needed to reduce the risk 10% more, and seven more days to reduce the risk 20% more; and (2) if an individual with a negative PCR test result has a negative antigen test result the next day, then his or her infection probability is between 0.6% and 0.7%. Conclusions: Five-day isolation has a proportionally greater effect on risk reduction, compared to longer isolation; and thus, if an isolation period of longer than five days is contemplated, both the risk reduction and the negative effects from such increased isolation should be considered. Regarding negative test certification, our results provide those in managerial positions, who must decide whether to accept the risk and hold mass-gathering events, with quantitative information that may be useful in their decision-making.

Quantifying the effect of isolation and negative certification on COVID-19 transmission (preprint)

Background: Isolation of close contact people and negative test certification are used to manage the spread of new coronavirus infections worldwide. These effectively prevent the spread of infection in advance, but they can lead to a decline in socioeconomic activity. Thus, the present study quantified the extent to which isolation and negative test certification respectively reduce the risk of infection.  Methods: A discrete-time SEIR model was used as the infectious disease model, and equations for calculating the conditional probability of non-infection status given negative test results on two different days were derived.  Results: The respective non-infection probabilities with two negative PCR test results, and with one negative PCR test result and one antigen test result, were quantified. By substituting initial parameters of the SEIR model into these probabilities, the present study revealed the following: (1) isolating close contact individuals can reduce by 80% the risk of infection during the first five days, but five more days are needed to reduce the risk 10% more, and seven more days to reduce the risk 20% more; and (2) if an individual with a negative PCR test result has a negative antigen test result the next day, then his or her infection probability is between 0.6% and 0.7%.  Conclusions: Five-day isolation has a proportionally greater effect on risk reduction, compared to longer isolation; and thus, if an isolation period of longer than five days is contemplated, both the risk reduction and the negative effects from such increased isolation should be considered. Regarding negative test certification, our results provide those in managerial positions, who must decide whether to accept the risk and hold mass-gathering events, with quantitative information that may be useful in their decision-making.  Trial registrations: Not applicable

Quantitative risk assessment of COVID-19 and serious illness among spectators at mass gathering events with vaccine-testing package implementation (preprint)

While mass gathering events have resumed in conjunction with vaccine-testing (VT) packages, their effects on reducing COVID-19 risk remain unclear. Here, we used an environmental exposure model to analyze the effects of vaccinations and proof of negative test results on reducing infection risk and serious illness among spectators at mass gathering events. We then analyzed the difference in risk with and without VT and regular seat zoning. Risk of infection and serious illness were quantified using a model incorporating parameters such as vaccination coverage, vaccine prevention effectiveness, and sensitivity of polymerase chain reaction (PCR) or qualitative antigen tests. When vaccine prevention effectiveness was 50% (corresponding to 4 months for the delta variant and 1-2 months for the omicron variant after the second vaccine dose), the risk of infection and serious illness among vaccinated spectators were 0.32-0.40 and 0.13-0.16 times of those who tested negative, respectively. In contrast, the risks of infection and serious illness among vaccinated spectators without measures such as mask wearing were 4.0 and 1.6 times higher than those among unvaccinated spectators with such measures, respectively. The risk of infection with an 80% vaccination coverage and a vaccine prevention effectiveness of 20% (corresponding to 5-6 months for the delta variant or 3-4 months for the omicron variant after the second vaccine dose) was comparable to that of a 20% vaccine coverage and a vaccine prevention effectiveness of 80% (corresponding to 1-3 months for delta variant after the second vaccine dose). Regarding zoning, there was little difference in risk with a vaccination coverage of [≥]80%. Adherence to individual measures after vaccination and maintenance of high vaccine effectiveness among spectators at stadiums are important for reducing risk of infection and serious illness. Furthermore, seat zoning did not affect overall infection risk reduction.

Assessment of COVID-19 risk and prevention effectiveness among spectators of mass gathering events (preprint)

There is a need to evaluate and minimise the risk of novel coronavirus infections at mass gathering events, such as sports. In particular, to consider how to hold mass gathering events, it is important to clarify how the local infection prevalence, the number of spectators, the capacity proportion, and the implementation of preventions affect the infection risk. In this study, we used an environmental exposure model to analyse the relationship between infection risk and infection prevalence, the number of spectators, and the capacity proportion at mass gathering events in football and baseball games. In addition to assessing risk reduction through the implementation of various preventive measures, we assessed how face-mask-wearing proportion affects infection risk. Furthermore, the model was applied to estimate the number of infectors who entered the stadium and the number of newly infected individuals, and to compare them with actual reported cases. The model analysis revealed an 86%-95% reduction in the infection risk due to the implementation of face-mask wearing and hand washing. Among the individual measures, face-mask wearing was particularly effective, and the infection risk increased as the face-mask-wearing proportion decreased. A linear relationship was observed between infection risk at mass gathering events and the infection prevalence. Furthermore, the number of newly infected individuals was also dependent on the number of spectators and the capacity proportion independent of the infection prevalence, confirming the importance of considering spectator capacity in infection risk management. These results highlight that it is beneficial for organisers to ensure prevention compliance and to mitigate or limit the number of spectators according to the prevalence of local infection. Both the estimated and reported numbers of newly infected individuals after the events were small, below 10 per 3-4 million spectators, despite a small gap between these numbers.