Pandemic collateral pain

PANAMA. Health officials around the world are trying to take precautions without inciting panic. Here are just a few of the questions facing them - and ultimately, us.

1. Is this a flu pandemic?

The influenza virus is constantly mutating. That's why we can't get full immunity to the flu, the way we can to diseases like chicken pox, because there are multiple strains of the flu virus and they change from year to year. However, even though the virus makes us sick, our immune systems can usually muster enough of a response so that the flu is rarely fatal for healthy people.

But every once in awhile, the virus shifts its genetic structure so much that our immune systems offer no protection whatsoever. (This usually happens when a flu virus found in animals swaps genes with other viruses and jumps to human beings.) A flu pandemic occurs when a new flu virus emerges for which humans have little or no immunity and then spreads easily from person to person around the world. The severe "Spanish flu" pandemic of 1918, which killed an estimated 40 to 50 million people worldwide.

The WHO has the responsibility of declaring when a new flu pandemic is underway, and to simplify the process, the U.N. body has established six pandemic phases. We're currently at phase 3. If the WHO upgraded that status to phase 4, which is marked by a new virus that begins to pass easily enough from person to person that we can detect community-sized outbreaks, such a move would effectively mean that we've got a pandemic on our hands.

The H1N1 swine flu virus has already been identified as a new virus, with genes from human and avian flus as well as the swine variety. It would seem that we've already met the criteria for phase 4. But though an emergency committee met on April 25 to evaluate the situation, the WHO hasn't made the pandemic declaration yet. The committee is set to meet again by April 28 at the latest.

As health officials have repeatedly emphasized, with good reason, the swine flu situation is evolving rapidly, and more lab tests are needed to ascertain exactly what is going on in Mexico and elsewhere.

2. What will happen if this outbreak gets classified as a pandemic?

Moving the world to pandemic phase 4 would be the signal for serious containment actions to be taken on the national and international level. Given that these actions would have major implications for the global economy, not to mention the effects of the public fear that would ensue, there is concern that the WHO may be considering politics along with science.

Of course, declaring a pandemic isn't a decision that should be taken lightly. For the WHO, phase 4 might trigger an attempt to keep the virus from spreading by instituting strict quarantines and blanketing infected areas with antivirals. But we appear to have missed the opportunity to contain the disease at its source since the virus is already crossing borders with ease.

That would leave the WHO and individual countries to fall back on damage control, using antivirals and old-fashioned infection control - like closing schools, limiting public gatherings and even restricting travel - to slow the spread of the virus. But such efforts would likely inflict serious damage on an already faltering global economy - and the truth is, we don't know how well those methods will work.

3. Why have the U.S. cases been so much milder than the ones in Mexico?

This is the question that has health officials from Geneva to Washington puzzled. In Mexico, swine flu has caused severe respiratory disease in a number of patients - and even more worryingly, has killed the sort of young and healthy people who can normally shrug off the flu. (Fueling such concerns is the fact that similar age groups died in unusually high numbers during the 1918 pandemic.) Yet the cases in the U.S. have all been mild and likely wouldn't have even garnered much attention if doctors hadn't begun actively looking

Some of the difference may be due to the fact that Mexico has apparently been grappling with swine flu for weeks longer than the US. As doctors across the US begin checking patients with respiratory symptoms for swine flu, CDC officials expect to see more severe cases in the US as well - and as better epidemiological work is done in Mexico, we'll probably hear about more mild cases there too. Right now, however, the true severity of the H1N1 swine flu virus is still an open question. The 1918 Spanish flu pandemic began with a fairly mild wave of infections in the spring, but the virus returned a few months later in a far more virulent form. That could happen with the current swine flu as well.

4. How ready is the world - to respond to a flu pandemic?

In some ways, the world is better prepared for a flu pandemic today than it has ever been. Thanks to concerns over H5N1 avian flu, the WHO, the US and countries around the world have stockpiled millions of doses of antivirals that can help fight swine flu as well as other strains of influenza. SARS and bird flu have given international health officials useful practice runs for dealing with a real pandemic. We can identify new viruses faster than ever before, and we have life-saving technologies - like artificial respirators and antivirals - that weren't available back in 1918.

At the same time, the very nature of globalization puts us at greater risk. International air travel means that infections spread very quickly. And while the WHO can prepare a new swine flu vaccine strain in fairly short order, we still use a laborious, decades-old process to manufacture vaccines capacity of doses - and even then, there wouldn't be enough for everyone on the planet.

The greatest risk from a pandemic might not turn out to be from the swine flu virus itself - especially if it ends up being relatively mild - but with "collateral damage" if governments respond to the emergency by instituting border controls and disrupting world trade. A 2008 World Bank report estimated that a severe pandemic could reduce the world's GDP by 4.8% -