Key findings:<p>-In every city included in the study, companies with no return to office vaccination policy had higher employee absences and higher health costs compared with businesses that implemented any vaccination policy.<p>-Businesses that required employees to be fully vaccinated before they returned to the office experienced no staff illnesses, missed workdays or increased expenses related to COVID-19.<p>-Businesses of 1,000 employees without an employee vaccination policy are likely to have an estimated 392 missed days of work over the upcoming fall and may spend $798,000 on COVID-19 health costs, on average.<p>-Businesses can prevent nearly 200 missed workdays in the fall from employee absences and save around $326,000 by strongly encouraging employees to get vaccinated before returning to the workplace.<p>-Businesses that strongly encouraged vaccination before entering the workplace can reduce workplace absences due to illness and lower COVID-19 health costs by 59%, compared with having no vaccination policy.<p>-Businesses in cities with lower vaccination rates in working adults, such as Charlotte, NC would most benefit from a vaccination policy, preventing nearly 610 missed days in the fall and saving approximately $1.2M in COVID-19-related health costs.<p>-Businesses located in cities with higher levels of vaccination coverage in working adults, like Hartford, CT, could also realize savings from a vaccination policy of about $324,000 in COVID-19 related health costs and prevent up to 210 missed days over the fall.