ZURICH, Aug 25 (Reuters) - Credit Suisse (CSGN.S) has asked all non-vaccinated staff in the United States to work from home beginning Sept. 7, as it pushes back its return-to-office plans over concerns about the spread of the COVID-19 Delta variant. A full return to the office has been delayed until Oct. 18, Switzerland"s second-largest lender told U.S. employees last week, while those without the COVID-19 shot have been told to stay home until receiving the vaccination or new guidance. "As concerns increase around the country regarding the Delta variant, we continue to strongly encourage all staff to get a COVID-19 vaccination and keep apprised of the latest updates to mask and physical distancing requirements in your area," the bank told U.S. employees in a memo seen by Reuters and confirmed by the company."This is especially important given the Delta variant"s higher contagion rate," it said. The news was reported earlier on Wednesday by Bloomberg. The spread of the Delta variant has prompted some Wall Street firms to rethink their back-to-office plans, while U.S. banks have started enforcing stricter mask and vaccine requirements for staff while trying to avoid a fierce national debate about individual rights. read more Credit Suisse"s new vaccine mandate puts it in line with Goldman Sachs (GS.N), Morgan Stanley (MS.N) and Citigroup (C.N), which have also made employee vaccination obligatory for entry into offices in the United States. read more