key: cord-0294534-z3k1mjqe
authors: Mori, K.; Mori, T.; Nagata, T.; Ando, H.; Hino, A.; Tateishi, S.; Tsuji, M.; Muramatsu, K.
title: COVID-19 vaccination coverage by company size and the effects of socioeconomic factors and workplace vaccination in Japan: a cohort study
date: 2022-04-02
journal: nan
DOI: 10.1101/2022.03.30.22273203
sha: 1d4f35cc31ce9686824718c729fbbf738291ffdc
doc_id: 294534
cord_uid: z3k1mjqe

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.

In Japan, the majority of the population had some level of initial vaccine hesitancy to 52 receive a COVID-19 vaccine [9, 10] . Nevertheless, by the end of December 2021, 53 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101 https://doi.org/10. /2022 approximately 80% of the population had received two vaccine doses [11] . In Japan, COVID-54 19 vaccination efforts began on February 17, 2021 using two mRNA vaccines: one from Pfizer 55 Inc. and one from Moderna Inc. In consideration of equitable vaccine allocation, the 56 vaccination of healthcare workers was followed by the vaccination of older adults [12] . 57 Thereafter, vaccination progressed through the general population in stages according to age. 58 An aspect of COVID-19 vaccination in Japan has been the availability of vaccination 59 at workplaces in addition to community settings provided by municipalities and clinics [12] . 60 Compared with other developed countries, the start of the vaccination program was delayed in 61 Japan. To make up for this delay, the government appointed a minister to be in charge and set The workplace COVID-19 vaccination program in Japan, however, may have 71 negatively affected the equitable allocation of vaccine doses. This program primarily targeted 72 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101 https://doi.org/10. /2022 large companies, with a minimum of 2,000 doses to be delivered to a single location (i.e., an 73 expected vaccination coverage of at least 1,000 persons [13] ). Thus, there were barriers to its 74 implementation in small and medium-sized companies. Therefore, company size may have 75 affected the timing and coverage of employees receiving the second COVID-19 vaccine dose. 76 We hypothesized that while the workplace vaccination program facilitated COVID-19 77 vaccination, there was a size-dependent difference among companies in the timing of 78 employees receiving the second vaccine dose and that this difference was influenced by the 79 availability of a company-arranged vaccination opportunity. In a survey conducted in Japan We conducted a prospective cohort study to examine the relationship between 89 company size and COVID-19 vaccination completion and the impact of the workplace 90 vaccination program on this relationship, focusing on the period between July and December 91 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted April 2, 2022. and the data were collected using a self-administered online questionnaire. All participants 99 gave informed consent, and the study was approved by the ethics committee of the University 100 of Occupational and Environmental Health, Japan (approval number: R2-079 and R3-006).

The baseline survey was conducted from December 22 to 25, 2020. The protocol for excluded if they were unemployed, over 65 years of age, or employed in the health or welfare September, completion by July or August would be coded "no" but completion by September, 123 October, November, and December would be coded "yes". In the baseline survey, we asked participants, "How many employees are there at your 127 company?" The participants could choose one of 10 options: 1 person (self-employed) or 2-4, 128 5-9, 10-29, 30-49, 50-99, 100-499, 500-999, 1000-9999, or 10,000 or more persons. We 129 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10. 1101 /2022 classified the responses into three categories: those who worked for small (1-49), medium-130 sized (50-999), or large (1,000 or more) companies. This classification was made because 131 under the Industrial Safety and Health Act, the obligation to establish an occupational health In the follow-up survey, we asked participants, "Has your company arranged an opportunity to 138 receive the COVID-19 vaccine at the workplace, whether or not you took advantage of the 139 opportunity?" Participants could choose one of three response options: yes, no, or unknown. 140 We regarded "yes" to indicate that the vaccination opportunity was arranged, and the other 141 answers to indicate that this was not arranged. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101/2022.03.30.22273203 doi: medRxiv preprint JPY, and 8.00 million JPY or greater. Educational background was classified into three 149 categories: junior high or high school, vocational school or college, and university or graduate 150 school. Marital status was classified into three categories: married, divorced or widowed, and 151 unmarried. Occupation was classified into 10 categories: general employee; manager; 152 executive manager; public employee, faculty member, or non-profit organization employee; 153 temporary or contract employee; self-employed; small office/home office; agriculture, forestry, 154 or fishing; professional occupation (e.g., lawyer, tax accountant); and other occupations. The odds ratios (ORs) for the association between company size and completion of the second 163 COVID-19 vaccine dose were estimated using a multilevel logistic model nested in the 164 prefecture of residence to account for regional variability. The multivariate model was adjusted 165 for sex and age (Model 1) and additionally adjusted for annual household income, educational 166 background, marital status, occupation, and industry (Model 2). Finally, the model was adjusted 167 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101/2022.03.30.22273203 doi: medRxiv preprint for company-arranged vaccination opportunity (Model 3).

A p-value of less than 0.05 was considered statistically significant. All analyses were Table 1 shows the participant characteristics by company size. Of the 15,829 participants, 4,272 174 (27%) worked for a large company, 5,117 (32%) for a medium-sized company, and 6,440 (41%) 175 for a small company. As the company size increased, the percentage of participants with a high 176 annual household income and a high educational background level increased. Furthermore, as 177 the company size increased, the opportunity for company-arranged vaccination increased: 56% 178 for large companies, 35% for medium-sized companies, and 14% for small companies. 179 <Insert Table 1> 180 Table 2 shows the ORs for the association between company size and completion of 181 the second COVID-19 dose by month. In the model adjusted only for age and sex (Model 1), 182 participants who worked for a medium-sized company were significantly less likely to 183 complete the second dose by August (OR=0.87, 95% CI: 0.79-0.94, p=0.001) and September 184 (OR=0.86, 95% CI: 0.78-0.93, p<0.001) than those who worked for a large company. For small 185 companies, the ORs decreased throughout the entire observation period, from July to December.

. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

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In the model adjusted for the main socioeconomic factors (Model 2), the ORs for medium-187 sized and small companies tended to approach 1. For August and September, this tendency 188 remained, but no significant difference was observed for the medium-sized companies. After Table 2> 197 198 199 This study showed that employees of smaller companies were less likely to have received a 200 second COVID-19 vaccine dose. In the months after the start of the workplace vaccination 201 program, the second dose completion rate of participants who worked for medium-sized 202 companies was lower than that of those who worked for large companies, but this difference 203 disappeared later in the observation period. The significant difference in completion rate 204 between small company employees and large company employees remained throughout the 205 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. Several studies have found differences in willingness to vaccinate depending on one's 221 occupation and industry [22] [23] [24] . In the current study, after adjusting for socioeconomic factors, 222 the difference in vaccination completion rate among employees of medium and large 223 companies disappeared. After these adjustments, the difference between employees of small 224 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10. 1101 /2022 and large companies also became smaller. These findings suggest that socioeconomic factors 225 affect the association between COVID-19 vaccination and company size in Japan.

In the present study, it was observed that participants who had a company-arranged 227 vaccination opportunity were significantly more likely to have received the second vaccine CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101/2022.03.30.22273203 doi: medRxiv preprint used to realize it warrant further discussion to ensure a more equitable implementation in future 263 infectious disease outbreaks.

It is unclear why there was significantly higher vaccination completion among 265 participants who worked for medium-sized companies compared with those who worked for CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101 https://doi.org/10. /2022 about their vaccination status in the follow-up survey. However, the impact of this situation 282 was likely small because second-dose vaccination was nearly complete in both the community CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. 

. CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101 https://doi.org/10. /2022 is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity.

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10.1101 https://doi.org/10. /2022 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted April 2, 2022. ; https://doi.org/10. 1101 /2022 . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

The copyright holder for this preprint this version posted April 2, 2022. . CC-BY 4.0 International license It is made available under a is the author/funder, who has granted medRxiv a license to display the preprint in perpetuity. (which was not certified by peer review)

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) Educational background Junior high or high school 1018 (23.8%) 1426 (27.9%) 2117 (32.9%) Vocational school, junior college or technical school 613 (14.4%) 1003 (19.6%) 1575 (24.5%) University or graduate school 2641

Agricultural, forestry, and fishing industries 2 (0.0%) 3 (0.1%) 135 (2.1%) Professional occupation (lawyer, tax accountant