Companies are turning to a private stockpile of antiviral drugs amid fears that Government supplies will be overwhelmed by a swine flu pandemic.
Meanwhile a website which offers the prescription medicine Tamiflu has reported receiving more than one million hits a day from members of the public after the first cases in Britain were confirmed.
While many firms have been planning for the eventuality for years, one major international company registered its entire 20,000 staff for a "pandemic preparedness plan" earlier this week.
Health care Connections, a private medical company, said that it had seen a spike in registrations for its protection plans, which it says guarantees access to flu treatment in the event of a pandemic, over the last few days.
Its website – easyfluprotection.co.uk – has also sold doses to 28,000 people this week alone.
"In recent days we've had unprecedented levels of enquiries from companies and individuals," said Alison Brown, its chief executive.
"Healthcare professionals recognise this has reached international public emergency status and we need to do everything we can to protect ourselves in the UK."
The surge in demand comes as companies urgently reassess their own emergency plans.
A string of FTSE 100 companies have already placed travel restrictions on their staff with many banning trips to Mexico.
Others are drawing up lists of employees who could potentially work from home to reduce the risk of infection and stockpiling equipment to hand out.