THERE are three approaches to an infectious disease: you can survive it (or not), kill off the bug responsible, or best of all prevent it. If swine flu goes pandemic, what should we do?
First, there鈥檚 treating it. The Mexican swine flu resists older antiviral drugs like rimantadine. It is still susceptible to the Tamiflu and Relenza in national stockpiles 鈥� such as they are 鈥� but virologists were shocked this past flu season when ordinary human H1N1 spontaneously developed near-total resistance to Tamiflu. Swine H1N1 could well do the same, particularly if it starts swapping genes with the human virus.
Our best hope might lie in monoclonal antibodies, which could both prevent infection and help fight it. These immune proteins can be engineered to recognise a specific virus, and then churned out in production plants. Several research groups have made monoclonal antibodies to H5N1 bird flu from the antibodies of survivors, and these have protected mice against H5N1. The same trick should work for swine flu 鈥� and once developed, large amounts could be produced in a matter of weeks. Several companies are already mass-producing flu monoclonals for ordinary H5N1, and could be switched to swine flu.
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Then there are treatments that help you survive flu symptoms rather than attacking the virus directly. Flu kills mainly by triggering a cytokine storm 鈥� runaway inflammation in the immune system. The steroids normally used to reduce inflammation don鈥檛 work, because they also suppress the immune responses you need to fight the virus. Last year, researchers in Hong Kong reported that combining Relenza with two readily available non-steroidal anti-inflammatory drugs called COX-2 inhibitors helped save mice from H5N1. This year, US researchers had similar success with an experimental anti-inflammatory drug.
Ultimately though, no one wants to catch a potentially lethal virus and it鈥檚 pretty hard to hide from pandemic flu. That leaves vaccines. Right now these are made from killed or weakened flu viruses. But growing them takes time: New Scientist has seen part of a confidential report for the International Federation of Pharmaceutical Manufacturers and Associations which says that in the next four months we can make a billion doses of pandemic vaccine at best, but more probably 340 million doses. This is not nearly enough for the world鈥檚 people. Very few countries have vaccine production plants, and people in those that don鈥檛 could get little vaccine or none (see 鈥淗ow the world threw away the chance to defeat a pandemic鈥�).
Other kinds of vaccine could be cooked up much faster in more countries. DNA vaccines are loops of DNA coding for the surface genes of the flu virus. Once injected into the skin, these are taken up by immune cells and turned into proteins. In the process, the immune cells learn how to recognise and fight the viruses that usually express those proteins 鈥� and even slightly different ones that might emerge as a pandemic evolves.
Peter Dunnill of University College London calculated in 2006 that the entire world could be vaccinated with a mere 150 kilograms of DNA vaccine, and called for a global task force to scale up production. It didn鈥檛 happen.
Meanwhile, several groups are looking for a universal vaccine that will work against all flu, once and for all. Several proteins common to all flu viruses show promise in animal and early human trials, and more were recently found that might prompt strong immune responses. Protein vaccines could be made in existing factories in the quantities needed. Under normal circumstances that wouldn鈥檛 happen without years of testing 鈥� but circumstances may no longer be normal.
鈥淪everal proteins common to all flu viruses show promise in animal and early human vaccine trials鈥�
