BY the morning of Thursday April 30th 2,500 Mexicans were known to have symptoms that looked like the result of a new strain of influenza, and more than 170 had died, though only eight of the dead were confirmed carriers of the new virus. That virus has now turned up in 12 other countries on four continents and the deaths have begun beyond Mexico’s borders, starting with a baby in Texas. This could be the beginning of an influenza pandemic.
On Wednesday the World Health Organisation (WHO) promoted the new disease to level five of its six-level pandemic alert. Some countries have built up stocks of antiviral drugs. Luckily, they seem to work against the new strain. Vigilance at borders is being redoubled. China and Russia have started quarantining visitors with suspicious symptoms. Asian airports have dusted off heat-sensing equipment they had installed after earlier scares caused by cases of avian flu and severe acute respiratory syndrome (SARS), to detect sick incoming passengers.
Could the new virus (a strain of the type of flu virus known as H1N1, H1 and N1 being the abbreviations for two of the virus’s characteristic proteins) be a dangerous pandemic in the making? Seasonal influenza comes and goes with the virus evolving slightly from one winter to the next. But every so often a truly new influenza virus emerges, to which few humans have immunity. The resulting global wave of infections is called a pandemic.
What makes influenza different is that it is so easy to catch. Seasonal influenza is one of the top ten causes of death in America, and in less developed countries the toll is higher. Influenza viruses are also astonishingly mutable. Their genetic make-up often changes by mistake when the cells they infect churn out new virus particles. On top of that, if an animal or human is infected with more than one strain at the same time, those strains may swap genes. Most such novelties will be evolutionary failures, but occasionally one will prosper and, because it is so new, its hosts’ immune systems will be unprepared for it. The result is a potentially pandemic virus.
That deaths from the new virus have mostly been confined to Mexico is probably a consequence of its having appeared there first and spread, under cover of normal seasonal flu, without anyone noticing. The suspected Mexican cases would then be the tip of an iceberg, and those who have died were just especially vulnerable or simply not treated as rapidly and effectively as they might have been in a richer country. It is also possible that there is something unique about Mexico, such as that those who died were infected with another virus which interacts lethally with the new one. Or a secondary and more lethal mutation might have emerged recently. That would be a serious problem for the rest of the world, as well as Mexico.
People worry about a new influenza pandemic for a 90-year-old reason. In 1918 and 1919 a pandemic known as “Spanish flu” (though it did not start in Spain) killed between 50m and 100m. Other influenza pandemics in 1889, 1957 and 1968 were milder. But even the most recent of these is reckoned to have killed at least 1m. A study published in the Lancet in 2006 used data from Spanish flu to predict that a modern pandemic of equivalent virulence would kill 62m people, with 96% of those deaths in low- and middle-income countries.
Even if the new virus is as virulent as the one that caused Spanish flu, a reason for hoping it will not cause so many deaths is that by good chance it is susceptible to certain antiviral drugs, including Tamiflu. But there is little hope of having enough antiviral treatments for all who would need them if a pandemic struck. What is more, if there were a pandemic it would be only a matter of time before a drug-resistant mutation of the virus emerged.
So how should governments prepare? Thankfully, prodding by the WHO and lessons from SARS and avian flu have caused governments to strengthen their disease-surveillance systems, improve communications between their health ministries and co-ordinate their stockpiling of drugs.
It is also time to begin work on a vaccine. The snag is that the world’s capacity to create a vaccine against pandemic influenza is based on the smaller amounts needed to fight seasonal flu. Both more, and more effective, vaccines will be needed. Some big vaccine-makers are bolstering the conventional approach with adjuvants. These are catalysts added to vaccines to improve their efficacy and reduce the amount of active ingredients required.
However, Peter Dunnil, a biochemical engineer at University College, London, says that, even under the most optimistic calculations, and taking adjuvants into account, today’s global vaccine-making capabilities would cover less than 10% of the world’s population. Furthermore, only nine countries—mostly in Europe—have enough indigenous capacity to supply their own people. Even the United States is not self-sufficient.
It is possible, though, that new technology will come to the rescue. Gregory Poland of the Mayo Clinic, an American hospital chain, argues that thanks to SARS, bird flu and fears about bioterrorism, work has been undertaken on a range of new incubation and manufacturing techniques. One example is DNA-based vaccines, which are made in cell cultures, not incubated slowly in eggs. Vocal, an American biotechnology firm, has shown in early tests that its DNA vaccine for potentially pandemic influenzas, such as strains of H5N1, is safe and effective, and it claims the technology can be scaled up easily.
If this swine flu is the next deadly pandemic, the world will curse itself for not being fully prepared. But it should not forget how much has been done in the past five years. Besides national and global stockpiles of antiviral drugs, medical equipment and financial resources, many countries and even businesses have developed plans for the outbreak of a pandemic.
Source: ECONOMIST
