The slow but constant migration westwards of bird flu over the last two years has sparked global fears of a pandemic on a scale not seen for almost 100 years. The fear is that a mutated human form of the disease could claim anything from 2m to 50m lives, damage the fabric of nations and, as the International Monetary Fund recently warned, severely disrupt capital flows and undermine the global economy.

While much has been written on the potential impact of a human strain of bird flu, the debate about the effect on business has, to an extent, taken place in private. It must now come out in the public arena because, unless addressed effectively, avian flu could trigger a global depression on the scale seen in the 1930s. If businesses are not prepared, and I fear many are not, this could further complicate any national and global response that is activated to manage and repel a flu pandemic.

As the chairman of a global business, I have paid close attention to the issue of avian flu. I believe it is an international business problem as much as a global threat and one that needs a high degree of co-ordination, shared intelligence and a common approach.

In the face of a pandemic, complacency today will mean an end to your business tomorrow. Consider this scenario: 50 per cent of your staff absent – sick, caring for ill relatives or too afraid to leave their homes. Many dead. For a global company that employs tens of thousands of people that would have a crippling impact, unless early provisions are put in place.

Then there are customers. If the businesses you serve do not get their planning and contingency right, you will have no market for your goods. You could have the world’s best plan and your entire workforce free from disease, but if your market is disrupted, the impact would be severe.

Fortunately, for many companies the emergence of severe acute respiratory syndrome in Asia four years ago provided a much needed wake-up call. It demonstrated the potential for a mass contagious disease to surface, and how in a globalised world, fed by international travel, one nation’s virus had the potential to become a world pandemic. Sars prompted many companies to revisit and update – or in some cases create – plans to deal with contagious diseases.

In my view, there are steps that companies can take now to prepare for the worst. First, assemble a working group within your business with respon­sibility for drafting contingency plans and co-ordinating any response. This team should comprise a cross-section of disciplines. These people are the epicentre of planning and reacting.

Second, make bird flu a board issue. Do not let contingency planning and decision-making slip down the organisation. The board and executive board should be the decision-making bodies for significant policy decisions such as when to quarantine staff, when to ban international travel and when to move to remote working.

Third, build a network of external experts. It is critical to be wired into the World Health Organisation, government bodies, medical experts and security advisers. You need an early warning system of any impending threat. At Reuters we have developed such a system, and also have the benefit of our reporters on the ground across the world. They play an important role.

Fourth, share your plans with your customers and clients. Gain an understanding of their response. There is no competitive advantage in having a better plan than your rival or customer. Your business needs their business to operate as smoothly as possible. At Reuters we have worked very closely with our key customers such as global banks and brokerages to co-ordinate a response. Finally, scenario planning. Test your systems, because your planning is only as good as the very worst-case scenario.

As businesses we have respons­ibilities to our staff, investors and customers to plan for all possible outcomes – we should also accept that we cannot plan for everything. But we have a responsibility not to drift into hype. The H5N1 virus has not mutated to a human form yet and only a small number of people have died. Almost all these people worked with or had close contact with poultry.

While the risk of a pandemic of human-form bird flu is small, we must quickly and quietly prepare ourselves – without alarming the people who work in and alongside our businesses. Sitting tight and hoping for the best is simply not an option.

The writer is chairman of Reuters and will lead a panel of experts to discuss the threat of avian flu at a Reuters Newsmaker event in London on April 25