Evaluation of workplace infection prevention and control measures for COVID-19: A prospective cohort study in Japan.

Background: Encouraging the implementation of infection prevention and control (IPC) measures has been necessary to prevent workplace infections caused by the coronavirus disease 2019 (COVID-19). However, the effectiveness of these measures in reducing infections has not been thoroughly evaluated. We evaluated employees' COVID-19 infection rates in relation to the implementation of IPC measures at their workplaces to identify effective workplace measures. Methods: This prospective cohort study was conducted between December 2020 and December 2021 using Internet-based self-assessment questionnaires, with 11,982 participants included from the baseline. To estimate whether implementing workplace IPC measures was associated with COVID-19 incidence rates among participants, we estimated multivariate-adjusted relative risk (RR) using a log-binomial model. Results: After adjusting for sex, age, education, household members, occupation-related factors, and personal preventive behaviors, requesting ill employees to refrain from going to work showed significantly lower COVID-19 infection rates than not requesting it (RR: 0.56, 95% CI: 0.34-0.91, p = 0.019). Conclusions: Employees restricted from reporting to work when ill had significantly lower COVID-19 infection rates than those who did not follow this measure. The results indicated that not coming to work when ill was effective in reducing COVID-19 infections at the workplace. We suggest that companies proactively adopt this policy and encourage their employees to comply with it.

Association between COVID-19 infection rates by region and implementation of non-pharmaceutical interventions: a cross-sectional study in Japan.

BACKGROUND: During a pandemic, non-pharmaceutical interventions (NPIs) play an important role in protecting oneself and others from infection. There are large regional differences in COVID-19 infection rates in Japan. We hypothesized that the local infection incidence may affect adherence to individual NPIs. METHODS: This cross-sectional study was conducted online among full-time workers in Japan in December 2020. The questionnaire asked the respondents to identify their habits regarding seven common NPIs (wearing masks, washing hands after the bathroom, disinfecting hands when entering indoors, gargling when returning home, ventilating the room, disinfecting or washing hands after touching frequently touched surfaces, carrying alcohol sanitizers when outdoors). RESULTS: A total of 27 036 participants were analyzed. Compared with the region with the lowest infection rate, five of the seven NPIs showed statistically significant trends across regional infection levels, the two exceptions being wearing masks and washing hands after the bathroom. Multivariate adjustment did not change these trends. CONCLUSIONS: This study found that NPIs were more prevalent in regions with higher incidence rates of COVID-19 in Japanese workers. The findings suggest that the implementation of NPIs was influenced not only by personal attributes but also by contextual effects of the local infection level.

The effects of telecommuting and family cohabiting situation on psychological distress in Japanese workers during the COVID-19 pandemic: A cross-sectional study.

OBJECTIVE: This study aimed to determine whether telecommuting's impact on psychological distress differed depending on the status of workers' cohabiting family members during the COVID-19 pandemic. METHODS: We collected data from 33 302 workers in Japan through an Internet survey, and included 27 036 valid responses in the analysis. The survey included items on family cohabitation and telecommuting status during the COVID-19 pandemic. We assessed workers' psychological distress using the Kessler 6. RESULTS: The psychological distress odds ratios (ORs) were higher for participants who lived with family members requiring care (OR = 1.38, P < .001), and lower for participants living with preschool children (OR = 0.77, P < .001) or a spouse (OR = 0.80, P < .001). Furthermore, odds ratios were higher for participants who worked from home and lived with family members requiring care or preschool children (OR = 1.52, P = .002; OR = 1.28, P = .028). Stratified by the presence or absence of family members living with them, psychological distress was higher for telecommuters with family members requiring care, preschool children, or elementary school children. CONCLUSION: The association between telecommuting and psychological distress varies, depending on workers' living situation with family members.

Workplace infection control measures and romantic activities of workers during COVID-19 pandemic: A prospective cohort study in Japan.

Objective: Due to the COVID-19 pandemic, non-married people are at high risk of loneliness. With social interactions restricted, it is important for non-married people to acquire a new romantic partner for their mental health and quality of life. We hypothesized that infection control efforts in the workplace influence people's social interactions, including romantic activities. Methods: We conducted an internet-based prospective cohort study from December 2020 (baseline) to December 2021, using self-administered questionnaires. Briefly, 27,036 workers completed the questionnaires at baseline, and when followed up after 1 year, 18,560 (68.7%) participated. A total of 6,486 non-married individuals with no romantic relationship at baseline were included in the analysis. At baseline they were asked about the implementation of infection control measures in the workplace, and at follow-up they were asked about activities they performed with a view to romantic relationships during the period from baseline to follow-up. Results: Compared to workers in workplaces with no infection control measures, the odds ratio (OR) associated with romance-related activities for those in workplaces with seven or more infection control measures was 1.90 (95% CI: 1.45-2.48, p < 0.001), and the OR associated with having a new romantic partner was 1.79 (95% CI: 1.20-2.66, p = 0.004). Discussion: Under the COVID-19 pandemic, the implementation of infection control measures in the workplace and the expressed satisfaction with those measures promoted romantic relationships among non-married, single individuals.

Personal infection prevention behaviors and campaign to encourage travel during COVID-19: A cross-sectional study.

Introduction: The Go To Travel campaign in Japan was launched to subsidize travel and accommodation costs for tourists through vouchers that could be used at domestic destinations. Infection prevention behavior can lead to refraining from travel owing to infection concerns; conversely, taking preventive action can promote travel. There is a lack of information about the association between infection prevention behaviors and desire to travel. During a pandemic of infection, there is the difficult challenge of balancing the promotion of infection prevention behavior with economic revitalization. Thus, we examined the relationship between personal infection prevention behaviors and using Go To Travel. Methods: We conducted a cross-sectional study of 26,637 workers who responded to a large-scale questionnaire survey about COVID-19 in Japan. We built multilevel logistic regression models adjusted for confounders to assess the association between each personal infection prevention behavior and using Go To Travel. We analyzed the seven infection prevention behavior individually: wearing a mask when among other people; disinfecting hands with alcohol before going indoors; washing hands after using the toilet; gargling upon returning home; opening a window to ventilate a room; carrying an alcohol sanitizer; and disinfecting hands after touching objects outside. Results: Among the 26,637 participants, 7,959 (30%) used Go To Travel. For "wearing a mask in the presence of others" and "washing hands after using the toilet," the majority of respondents answered "almost always: 86.5 and 85.6% respectively. Action "carrying alcohol disinfectant" was the least implemented, with 36.9% of respondents saying "almost never." Two of the seven preventive behaviors ("disinfecting hands with alcohol before going indoors" and "carrying alcohol disinfectant") were positively related to using Go To Travel, that is, the more of these actions they took, the more they used Go To Travel (p for trend <0.001). Conclusions: To balance pandemic preparedness with economic preparedness, it is also necessary to promote travel when the infection situation is calm. However, since human mobility can be a factor that exacerbates the infection situation, it is necessary to promote more infection prevention behaviors among individuals. We confirmed that Go To Travel users were basically doing a good infection prevention behaviors, but they tended not to wash their hands after touching things or carry alcohol sanitizer. It is necessary to encourage these measures to be taken when traveling.

Association between preventive measures against workplace infection and preventive behavior against personal infection.

To prevent the spread of infection, it is necessary for each individual to adopt infection prevention behavior. We investigated the effect of infection control measures implemented in the workplace on personal infection prevention behavior. We conducted a self-administered questionnaire survey through the Internet from December 22 to 25, 2020, during which period coronavirus disease 2019 (COVID-19) was spreading. Among respondents aged 20 to 65 years (n=27,036), 21,915 workers were included in the analysis. The results showed that as the number of infection control measures in the workplace increased, implementation of infection prevention behavior by individuals also significantly increased. However, the relationship differed depending on the type of personal infection prevention behavior. Specifically, infection control measures against COVID-19 in the workplace may affect personal infection prevention behavior. Implementation of infection control measures in the workplace increases awareness of the importance of individual infection prevention behavior and its implementation by all individuals. These findings may be applicable not only to COVID-19 measures but also to responses to other emerging infections and seasonal influenza.

Relationship between Psychological Distress and Poverty among Japanese Workers during the COVID-19 Pandemic: A Prospective Cohort Study.

OBJECTIVE: This study aimed to examine the relationship between psychological distress and poverty among Japanese workers during the COVID-19 pandemic. METHOD: An internet based prospective cohort study was conducted. A total of 11,081 individuals who were not experiencing poverty at baseline in December 2020 were included. The exposure variable was psychological distress evaluated using the Kessler 6 scale at baseline. The outcome variable was whether participants were experiencing poverty at the one-year follow-up, as defined by household financial distress. RESULT: Compared to individuals without psychological distress, the adjusted odds ratios of household financial distress among those with mild and severe psychological distress were 2.88 (95% CI: 2.47-3.33, p < 0.001) and 3.19 (95% CI: 2.52-4.04, p < 0.001), respectively. CONCLUSION: Workers' psychological distress is a notable public health concern in the context of poverty.

Effect of COVID-19 infection related experiences on social behaviors when a state of emergency is declared: a cohort study.

BACKGROUND: Restricting the movement of the public to gathering places and limiting close physical contact are effective measures against COVID-19 infection. In Japan, states of emergency have been declared in specific prefectures to reduce public movement and control COVID-19 transmission. We investigated how COVID-19 infection related experiences including people with a history of infection, people with a history of close contact, and people whose acquaintances have been infected, affected self-restraint from social behaviors during the second state of emergency in Japan. METHODS: A prospective cohort study was conducted among workers aged 20-65 years using data from an internet survey. The baseline survey was conducted on December 22-25, 2020, and a follow-up survey was on February 18-19, 2021. There were 19,051 participants who completed both surveys and were included in the final analysis. We identified eight social behaviors: (1) eating out (4 people or fewer); (2) eating out (5 people or more); (3) gathering with friends and colleagues; (4) day trip; (5) overnight trip (excluding visiting home); (6) visiting home; (7) shopping for daily necessities; and (8) shopping for other than daily necessities. We set self-restraint regarding each social behavior after the second state of emergency was declared in January 2021 as the dependent variable, and COVID-19 infection related experiences as independent variables. Odds ratios were estimated using multilevel logistic regression analyses nested in the prefecture of residence. RESULTS: Significant differences by COVID-19 infection related experiences were identified: compared to people without COVID-19 related experiences, people with a history of COVID-19 were less likely self-restraint from most social behaviors. People whose acquaintance had been diagnosed with COVID-19 were significantly more likely to refrain from most social behaviors. There was no significant difference in any social behaviors for people with a history of close contact only. CONCLUSION: To maximize the effect of a state of emergency, health authorities should disseminate information for each person in the target population, taking into account potential differences related to the infection related experiences.

Association of alcohol consumption and frequency with loneliness: A cross-sectional study among Japanese workers during the COVID-19 pandemic.

Background: There are increasing concerns that prevention measures against coronavirus disease 2019 (COVID-19) such as social distancing and telework are leading to loneliness and poor lifestyle habits like increased alcohol consumption. The purpose of this study was to assess whether loneliness reported among workers during the COVID-19 pandemic is associated with changes in alcohol consumption. Methods: The study comprised a cross-sectional, online survey of 27,036 workers between December 22 and 26, 2020. A questionnaire was used to assess loneliness, usual alcohol consumption and whether that consumption had changed. Odds ratios (ORs) were estimated by logistic regression analysis. Results: A total of 2831 (10.5%) workers indicated they had increased alcohol consumption during the pandemic. Increased alcohol consumption was significantly associated with loneliness (OR = 1.94, 95%CI 1.70-2.21). This association held true for those who indicated they drank two or more days per week (OR = 1.98 95%CI 1.71-2.30) and those who drank less than one day per week (OR = 1.51 95%CI 0.71-3.25). In contrast, there was no association between increased alcohol consumption and loneliness among those who indicated they hardly ever drank (OR = 1.22 95%CI 0.55-2.72). Conclusions: Among those drinking more than once a week, increased alcohol consumption is associated with loneliness.

Occupational Factors Associated with Telemedicine Use in the Japanese Working-Age Population: A Web-Based Study Conducted during the COVID-19 Pandemic.

Telemedicine has significant potential for helping workers access medical treatment. To improve workers' access to telemedicine, it is important to analyze current utilization rates and influencing factors. Therefore, the purpose of this study is to evaluate the associations between occupational factors and telemedicine use. A 1-year follow-up study of 4,882 full-time workers receiving regular treatment in Japan was conducted from December 2020 to December 2021. Occupational factors associated with the use of telemedicine were evaluated by multivariate logistic regression analysis. In total, 191 participants had experience of using telemedicine (3.9%). The most common comorbidity was hypertension (37.0%), followed by back pain and arthritis (19.8%) and depression and psychiatric disorders (14.5%). Managers and executives [adjusted odds ratio (aOR) = 1.92, 95% confidence interval (CI): 1.68-3.43, P < = 0.026], finance industry workers (aOR = 2.61, 95% CI: 1.24-5.49, P = 0.011), and individuals with experience of teleworking (aOR = 2.08, 95% CI: 1.52-2.85, P < 0.001) were more likely to use telemedicine. Telemedicine usage was least common among workers aged 50-59 years (aOR = 0.35, 95% CI: 0.22-0.57, P < 0.001) and those with long working hours (≥ 9.0 hours/day) (aOR = 0.59, 95% CI: 0.38-0.93, P < 0.022). The utilization rate of telemedicine in Japan is still low. This study identified occupational factors related to the use of telemedicine, such as worker's age, employee status, working hours, and experience of teleworking. Our findings suggest that flexible work arrangements could promote widespread use of telemedicine.

Corporate health culture promotes infection control measures against COVID-19 in the workplace.

OBJECTIVES: The present study examined the relationship between health culture evaluated by the Health and Productivity Survey Sheets and the implementation status of infection control measures against COVID-19 in the workplace. METHODS: This was a cross-sectional study using the corporate data (2518 companies) collected for the purpose of selecting the excellent company of health and productivity management by the Japanese government. The explanatory variable was the overall evaluation score, and the outcome was whether or not infection control measures against COVID-19 in the workplace. We used logistic regression analysis and calculated the odds ratio adjusted for the industry sector, the corporation size, and the operating profit ratio by the overall evaluation score category. RESULTS: The odds ratio of all infection control measurements in the workplace increased as the evaluation score increased. CONCLUSIONS: This study revealed a new finding that the presence of a healthy culture in the workplace will lead to the appropriate implementation of infection control measures during a pandemic. The company's ordinary commitment to employee health will be effective even in times of health crisis, such as during the outbreak of the pandemic.

Association between Perceived Organizational Support for Infection Prevention and Work Engagement during the COVID-19 Pandemic among Japanese Workers: A Prospective Cohort Study.

Although the correlation between perceived organizational support (POS) and work engagement has been investigated in several studies, the relationship between health-focused POS and work engagement has not been clarified. We prospectively evaluated the influence of workers' POS for infection prevention (POS-IP) on employees' work engagement. This prospective cohort study was conducted from December 2020 (baseline) to December 2021 (1-year follow-up) using a self-administered internet questionnaire. At follow-up, there were 18,560 respondents, and after excluding 6677 respondents who had changed jobs or retired since baseline or who were self-employed; thus, 11,883 participants were included in the analysis. We asked participants a single question on POS-IP and the three-item Utrecht Work Engagement Scale (UWES-3), and then analyzed the relationship between POS-IP at baseline and UWES-3 at follow-up using multilevel regression analysis. Work engagement at follow-up was significantly higher in the groups with "low", "high", and "very high" POS-IP at baseline as compared with the "very low" group (all, p < 0.001). A dose-response relationship was also observed between the POS-IP categories at baseline and work engagement at follow-up (p for trend < 0.001). During the COVID-19 pandemic, POS-IP can increase work engagement after 1 year.

Workplace Infection Control Measures and Perceived Organizational Support During the COVID-19 Pandemic in Japan: A Prospective Cohort Study.

OBJECTIVE: We investigated whether workplace infection control measures during the COVID-19 pandemic could increase perceived organizational support (POS). METHODS: This prospective cohort study was conducted in Japan from December 2020 to December 2021 using a questionnaire survey. There were 18,560 respondents at follow-up; we investigated 4971 who rated low POS at baseline. The participants were asked a single question about POS and nine about workplace infection control measures. We determined the odds ratios (ORs) of high POS at follow-up using multilevel logistic regression analysis. RESULTS: The groups of 5 to 6 (OR = 1.29, 95% confidence interval = 1.05-1.57, P = 0.014) and 7 to 9 workplace infection control measures (OR = 1.54, 95% confidence interval, 1.28-1.85, P < 0.001) had significantly higher ORs than the group with 0 to 2 measures. CONCLUSIONS: Health support for employees through workplace infection control measures can increase POS.

Workplace vaccination opportunity against COVID-19 contributed to high perceived organizational support of employees in Japan: A prospective cohort study.

OBJECTIVES: Perceived organizational support is a broad perception by employees about the extent to which their employer values their contributions and cares about their well-being. We examined the relationship between workplace vaccination opportunities for COVID-19 provided by companies and increases and decreases in perceived organizational support, using a prospective cohort study. METHODS: This study was conducted between December 2020 and December 2021 using a self-administered questionnaire survey in Japan. In total, 18 560 people responded to the follow-up, and were included in this study. The odds ratios (ORs) for the association between company-arranged vaccination opportunities and high perceived organizational support at the follow-up for participants (a) with low perceived organizational support at the baseline (n = 4971), and (b) with high perceived organizational support at the baseline (n = 6912) were separately estimated using a multilevel logistic model. RESULTS: The OR of high perceived organizational support at the follow-up after low baseline levels was significantly higher in participants given a vaccination opportunity than those not given this opportunity (OR 1.49; 95% confidence interval [CI] 1.32-1.67; p < .001). The OR of high perceived organizational support at the follow-up after high baseline levels was also significantly highly in participants given a vaccination opportunity than not (OR 1.38; 95% CI 1.23-1.54; p < .001). These significant differences remained after adjusting for workplace infection control measures. CONCLUSIONS: Employee health support provided through a workplace vaccination program can contribute to high perceived organizational support.

Effect of working place infection control practices on workers' psychological distress: A large-scale cohort study during the COVID-19 pandemic in Japan

Background The COVID-19 pandemic has dramatically transformed the work environment and practices worldwide. Long-term infection control practices may increase the psychological distress of workers, and, conversely, inadequate infection control practices in the working place may increase the fear of infection. This study aimed to determine the relationship between infection control practices in the working place and employee mental state during the COVID-19 pandemic in Japan. Methods This study was conducted in December 2020 and February 2021. The participants had undergone a preliminary survey, which revealed that they were in a good mental state. Their psychological distress was investigated via a second survey, and the factors associated with distress were studied using a logistic model. Results The results of the second survey indicated that 15.3% of participants demonstrated psychological distress. This was associated with leave-of-absence instructions, instructions for shortening business hours, and requests to avoid the working place in case of any symptoms. Conclusion The study found that while some infection control practices reduce workers' distress, others worsen it. Employers need to consider infection control practices as well as the worsening mental state of employees following a decrease in income caused by such measures. Follow-up studies may be necessary to clarify the long-term effects on workers' mental states.

Job stress and loneliness among desk workers during the COVID-19 pandemic in Japan: focus on remote working.

BACKGROUND: Previous studies have reported an increase in loneliness since the outbreak of coronavirus disease 2019 (COVID-19), but there are few data on the relationship between job stress and loneliness. This study aimed to assess the relationship between job stress and loneliness among desk workers, with a focus on the impact of remote working. METHODS: This study was part of the Collaborative Online Research on the Novel-coronavirus and Work (CORoNaWork) project in Japan. We extracted data from 13,468 workers who indicated that they were doing desk work. Loneliness was assessed using a single question and job stress was valuated using the Job Content Questionnaire (JCQ). Multiple logistic regression was performed. RESULTS: Participants who worked remotely 4 or more days per week were marginally more likely to report feeling lonely compared with those who did not work remotely (adjusted odds ratio = 1.23, 95% CI: 0.99-5.84, P = 0.066). Remote working did not explain the interaction between JCQ scale scores and loneliness. Among remote workers, the level of support provided by co-workers and supervisors was strongly associated with feelings of loneliness as well as non-remote workers (co-worker support: AOR = 4.06, 95% CI: 2.82-5.84, P < 0.001; supervisor support: AOR = 2.49, 95% CI: 1.79-3.47, P < 0.001). CONCLUSIONS: To reduce loneliness and the risk of associated mental health problems, high-frequency remote workers should interact with supervisors and co-workers using the information and communication technology developed for this purpose.

Spread of infection and treatment interruption among Japanese workers during the COVID-19 pandemic: A cross-sectional study.

Background: The COVID-19 pandemic has resulted in treatment interruption for chronic diseases. The scale of COVID-19 in Japan has varied greatly in terms of the scale of infection and the speed of spread depending on the region. This study aimed to examine the relationship between local infection level and treatment interruption among Japanese workers. Methods: Cross-sectional internet survey was conducted from December 22 to 26, 2020. Of 33,302 participants, 9,510 (5,392 males and 4,118 females) who responded that they required regular treatment were included in the analysis. The infection level in each participant's prefecture of residence was assessed based on the incidence rate (per 1,000 population) and the number of people infected. Age-sex and multivariate adjusted odds ratios (ORs) of regional infection levels associated with treatment interruption were estimated by multilevel logistic models, nested by prefecture of residence. The multivariate model was adjusted for sex, age, marital status, equivalent household income, educational level, occupation, self-rated health status and anxiety. Results: The ORs of treatment interruption for the lowest and highest levels of infection in the region were 1.32 [95 % confidence interval (CI) were 1.09-1.59] for the overall morbidity rate (per 1,000) and 1.34 (95 % CI 1.10-1.63) for the overall number of people infected. Higher local infection levels were linked to a greater number of workers experiencing treatment interruption. Conclusions: Higher local infection levels were linked to more workers experiencing treatment interruption. Our results suggest that apart from individual characteristics such as socioeconomic and health status, treatment interruption during the pandemic is also subject to contextual effects related to regional infection levels. Preventing community spread of COVID-19 may thus protect individuals from indirect effects of the pandemic, such as treatment interruption.

A Prospective Cohort Study of Presenteeism and Increased Risk of Divorce Among Japanese Workers.

OBJECTIVE: We examined the association between the presenteeism and the risk of divorce among Japanese workers during the COVID-19 pandemic. METHODS: A prospective study of 27,036 individuals was conducted starting in December 2020, with 18,560 (68.7%) participating in the follow-up in December 2021. The Work Functioning Impairment Scale (WFun) was used to measure the degree of work function impairment. RESULTS: Compared with the group with the lowest WFun score, the odds ratio for the group with moderate WFun was 1.16 (95% confidence interval, 0.74 to 1.82; P = 0.525), and the odds ratio for the group with the highest WFun was 1.76 (95% confidence interval, 1.18 to 2.62; P = 0.006). CONCLUSIONS: This study suggests that supporting workers with presenteeism has important implications not only from the perspective of labor productivity in management but also for the individual's quality of life in terms of family relationships.

Workplace infection prevention control measures and work engagement during the COVID-19 pandemic among Japanese workers: A prospective cohort study.

OBJECTIVES: Our objective was to assess the effect of appropriate workplace IPC measures on employees' work engagement. It could be important to note how workplace infection prevention control (IPC) measures for COVID-19 contribute to positive mental health among workers. We hypothesized that if workplace IPC measures are adequately implemented, they would have a positive effect on employees' work engagement. METHODS: We conducted an internet-based prospective cohort study from December 2020 (baseline) to December 2021 (follow-up after 1 year) using self-administered questionnaires. At baseline, 27036 workers completed the questionnaires, while 18 560 (68.7%) participated in the one-year follow-up. After excluding the 6578 participants who changed jobs or retired during the survey period, or telecommuted more than 4 days per week, 11 982 participants were analyzed. We asked participants about the implementation of workplace IPC measures at baseline and conducted a follow-up using a nine-item version of the Utrecht Work Engagement Scale (UWES-9). RESULTS: Four groups were created according to the number of workplace IPC measures implemented. The mean (SD) UWES-9 score of the "0-2" group was the lowest at 18.3 (13.2), while that of the "8" group was the highest at 22.6 (12.6). The scores of the "3-5," "6-7," and "8" groups were significantly higher than that of the "0-2" group (all, p < .001). The p trend of the four groups was also significant (p < .001). CONCLUSIONS: Promoting workplace IPC measures improves workers' work engagement, and a dose-response relationship exists between workplace IPC measures and work engagement.

COVID-19 vaccination coverage by company size and the effects of workplace vaccination program in Japan: a cohort study.

BACKGROUND: Vaccination is considered the most effective control measure against COVID-19. Vaccine hesitancy and equitable vaccine allocation are important challenges to disseminating developed vaccines. To promote COVID-19 vaccination coverage, the government of Japan established the workplace vaccination program. However, while it appears that the program was effective in overcoming vaccine hesitancy, the program may have hindered the equitable allocation of vaccines because it mainly focused on employees of large companies. We investigated the relationship between company size and COVID-19 vaccination completion status of employees and the impact of the workplace vaccination program on this relationship. METHODS: We conducted an internet-based prospective cohort study from December 2020 (baseline) to December 2021. The data were collected using a self-administered questionnaire survey. Briefly, 27,036 workers completed the questionnaire at baseline and 18,560 at follow-up. After excluding ineligible respondents, we finally analyzed the data from 15,829 participants. At baseline, the participants were asked about the size of the company they worked for, and at follow-up they were asked about the month in which they received their second COVID-19 vaccine dose and the availability of a company-arranged vaccination opportunity. RESULTS: In each month throughout the observation period, the odds of having received a second COVID-19 vaccine dose were significantly lower for small-company employees than for large-company employees in the sex- and age-adjusted model. This difference decreased after adjusting for socioeconomic factors, and there was no significant difference after adjusting for the availability of a company-arranged vaccination opportunity. CONCLUSIONS: The workplace vaccination program implemented in Japan to control the COVID-19 pandemic may have been effective in overcoming vaccine hesitancy in workers; however, it may have caused an inequitable allocation of vaccines between companies of different sizes. Because people who worked for small companies were less likely to be vaccinated, it will be necessary to enhance support of vaccination for this population in the event of future infectious disease outbreaks. TRIAL REGISTRATION: Not applicable.