Columbia International Affairs Online: Working Papers

CIAO DATE: 06/2009

Travel Restrictions Not a Cure for Swine Flu Outbreak

Michael T. Osterholm

April 2009

Council on Foreign Relations


Michael T. Osterholm, Director of the Center for Infectious Disease Research and Policy (CIDRAP), University of Minnesota

Toni Johnson, Staff Writer,


The outbreak of a new strain of deadly swine flu, which has killed more than one hundred people in Mexico and spread to the United States and Europe, has global health experts considering whether this may be the start of a long-feared pandemic. Michael T. Osterholm, director of the Center for Infectious Disease Research and Policy at the University of Minnesota, says there are a lot of unknowns about the new flu strain but so far it presents "a very different picture" from that of recent avian flu outbreaks and the 2003 sudden acute respiratory syndrome (SARS) outbreak. " Osterholm says it may be a matter of months before experts understand the disease. He cautions against international policy overreactions, citing some countries' travel warnings and bans on some imported foods from the United States and Mexico as "hysterical." He says the best way to deal with panics is to keep people informed and not create false expectations.

How does this illness compare to other outbreaks that have recently occurred such as SARS and avian flu?

First of all, we are in the earliest days of this situation and this time really don't know how this illness will work--both in terms of its severity or in terms of the number of cases in the next several weeks to months. As far as what it might do, it's very clear now that it has basically obtained the capability of being transmitted by people to people, which distinguishes it from the avian influenza situation in Asia and [North] Africa. While [avian flu] is a concern, it's an illness that has yet to develop the capacity to go person to person. That is one of the most important ingredients in an influenza strain of animal origin becoming the next human pandemic strain--that ability to go person to person.

In terms of influenza versus diseases like SARS, they are so different. Although SARS has the ability to be transmitted person to person, it's actually one that is relatively hard to do. Much of the transmission we saw with SARS, the outbreak that originated in Asia, had to do with transmission from those persons hospitalized having various respiratory procedures done that actually enhanced the transmission of the virus. In addition, much of the transmission with SARS occurred many days into the illness of the individual, whereas with influenza [people] can actually be infectious well before they even know they're sick. So that when you put this all together, this is just a very different picture.

What we don't know is: Will this continue to be transmitted between people to people? Will the clinical picture change if we look at previous pandemics of influenza? For example, in the 1918 pandemic there was a first wave that occurred in April and May of that year with a swine flu strain that then suddenly disappeared. It just literally was not present. Then from really nowhere in August of that same year it came back--we had a second wave--and with a vengeance such that we had that very famous 1918 pandemic that killed anywhere between 40 million and 100 million people. So we're not sure what this one is going to do. Will it, in fact, fizzle out over the next six to eight weeks? Very possible. Will it actually fizzle out in six to eight weeks but not disappear--meaning it could come back as a second wave this summer, this fall, this winter? Very possible. Could this actually be the first punch in a pandemic boxing match in that as it passes through more people it may get more severe? It might even get milder, we don't know. That's all possible too. So in the end, there is a lot of unknowns in these very early days, and while that's unsettling for people, that's just the scientific truth and we have to tell that story and continue to follow this closely.

There have been some measures we are starting to see from countries, from travel advisories to screening incoming passengers to banning pork from Mexico and the United States. Are these types of containment measures effective?

Most often they are hysterical and they provide no benefit to reducing disease transmission. Second of all, while we want to limit transmission around the world, there are some of us who debate how possible that really is. What we have to do is look at the collateral damage that would occur if in fact we do shut borders. [If they are shut] there are many critical lifesaving drugs that are made in Asia that will never make it to the United States, where people will die from not having those drugs. There are many kinds of medical products that are out there where people will not in fact have access to them because they never made it here from some other country. Food supplies will be disrupted. When one starts looking at this, it's not a no-sum-lost game with closing borders and doing some these things. We have to look at what will happen and what the implications are. And I don't think that's been nearly carefully enough evaluated.

How do you deal with panics if you are a global health professional?

You just have to keep telling people the truth--what do we know, what do we not know. We're going to get through this. These are the issues that are before us. Here's an example. We have seen pictures in the last two days of mass distribution of masks in Mexico. Mark my words, one of the things that is very likely to happen is in the next couple of days all those masks are going to start to run out. People aren't going to have any more. They use them for a couple of days and the stockpile is all gone. And when that happens people are going to panic because they're going to want their masks and they're not getting them handed out to them every day. And it turns out that masks probably are really limited in their ability to stop transmission. And yet now we have created this response crutch that people will use to say, "I had a mask last week and why don't have one this week." That's what people don't understand.

How well are countries working together on this?

They are working extremely well. The United States has done a great job, I really give credit to the [Centers for Disease Control]. They really have done a remarkable job and I think Canada and Mexico have stepped up, too.