Global banks are already scrambling to split their workforces to reduce the risk that large numbers of employees fall ill, and testing backup sites to ensure they can continue doing business even if they can no longer access Wall Street or locations in central London.

JPMorgan Chase (JPM) has started dividing its sales and trading teams between separate offices. It told employees in an email that this is a “precautionary measure” to make sure the bank can continue to run smoothly. The firm runs alternate sites in Brooklyn and New Jersey, and in Basingstoke, about 50 miles southwest of London.

Bank of America (BAC) said it is splitting its fixed income and equities trading teams from Monday, sending some people to a backup site in Stamford, Connecticut. Deutsche Bank (DB) said it has split some London operations and trading teams, with some employees working from home.