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Killing Flu With A Single Shot

Scientists may soon be ready with a vaccine against influenza that promises to offer protection against pandemics too…… P. Hari reports

…………………… & see

Few people in India vaccinate themselves against influenza, but it is an annual ritual in many countries. In the US, many citizens get themselves flu shots around this time, year after year. Influenza (not to be confused with avian flu) is a major disease all over the world, making millions of people sick every year. According to the World Health Organisation (WHO), 10-20 per cent of the world population gets infected with the flu virus every year. This leads to 3-5 million hospitalisations and up to 500,000 deaths annually.

Yet getting vaccinated against influenza is not as easy as it sounds. There are many different varieties of the influenza virus, and one vaccination protects against only one of these. Besides, the vaccinations have to be repeated every year. The virus mutates as well, making the development of the vaccines difficult. But these problems could soon go away — scientists are developing what is called a universal flu vaccine, one that could give protection for a lifetime against a variety of flu viruses.

The new vaccine was developed by two European universities — the University of Ghent and the Interuniversity Institute for Biotechnology (VIB) in Flanders. It has subsequently been passed on to the British firm Acambis which is carrying out further work on the vaccine. Recently, it crossed the first stage of clinical trials. In a few years, if the vaccine goes through Phase II and III clinical trials, we may not need to get flu vaccinations repeatedly, thereby saving enormous time and money. In the US alone, influenza costs the economy $10 billion a year.

The value of a universal flu vaccine can be gauged if one looks at past influenza epidemics. In the last 100 years, the world has seen three influenza pandemics. The first one, called the Spanish Flu, killed more than 60 million people from 1918 to 1920. The second one, called the Asian Flu, killed around 1.5 million people in 1957-58. The Hong Kong Flu killed around 1 million in 1968. There has not been a major pandemic since then. Since the virus mutates regularly, a flu pandemic is a disaster waiting to happen, even if we discount avian flu, which could become a global disaster like never seen before.

The rapid mutation of the virus is the most serious hurdle in developing an effective vaccine. If the virus mutates, few people will have immunity to the new form. It takes almost a year to develop a vaccine, during which time a truly virulent form could kill millions of people. So efforts were underway to see what portion of the virus gene remains unchanged in all the varieties. It is this portion that is the basis of the universal vaccine.

In the 1990s, scientists at VIB discovered a region — called M2e — in the influenza virus gene that remains common to all the mutated varieties of the type A form of the virus. This type is the most common form of the virus, and thus scientists expect a vaccination against type A to stop a pandemic. The vaccinations currently given are all against type A, but they do not use this common region. In laboratory animals, the M2e vaccine provided total protection against all influenza A strains. Moreover, no side effects were noticed.

VIB had licensed the rights to the vaccine to the British vaccine company Acambis. In the Phase I trials done by the company in the US, the vaccine reportedly generated a good immune response with no side effects.

Interestingly, the vaccine was also tested in ferrets against avian flu. In the experiment, about 70 per cent of the animals which received the vaccine survived, while all the animals which did not died. While these results do not automatically translate into a vaccine for avian flu, they are good enough for immunologists to take them seriously.

So if there is an avian flu pandemic, a vaccine based on M2e might provide some protection. But that is not the primary goal of the universal vaccine, whose developers hope that two vaccine shots would be enough to protect against influenza for a long time.

Sources: The Telegraph (Kolkata, India)

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