This is (hopefully) the first in a series of posts on our government's response to the threat of pandemic avian influenza. It focusses on what medications can be used to deal with bird flu, what we have done to stockpile these medications, and whether, as a result, we can expect them to be widely available. (Short answer: no.)
There are two main ways to deal with avian influenza: vaccines, which protect us from getting it, and antivirals, which can either be given prophylactically, to protect people who are not yet infected, or to treat avian influenza once someone has it. I'll deal with them separately.
Vaccines: To its great credit, the US has commissioned two companies to begin work on a vaccine against the H5N1 strain of avian flu -- the strain that has people worried. One of these companies -- Sanofi Pasteur -- has tested its vaccine, with positive results. (Revere of Effect Measure has some concerns about these results here.) However, there are some very serious problems with the idea that we will be able to rely on vaccines to any significant extent in an avian flu pandemic. These problems are: first, it's not clear that we have the right vaccine; second, it will take months to produce it; and third, we don't have nearly enough capacity to produce enough vaccine for everyone in any case. Taking these in turn:
First: the strain used to create these vaccines is from 2004. The virus has been evolving since then, and will continue to evolve. For this reason, it's not clear that the vaccine we are now testing will work against any strain of avian flu that actually shows up here. (See here for more.) If we don't have the right strain, we will need to develop a new vaccine from scratch, and that will take time -- at least six months.
Second: the actual process of growing vaccines is long and cumbersome. The LA Times cites the Department of Health and Human Services as saying that it would take six to eight months to produce vaccine -- six to eight months during which the pandemic would be raging.
Third, the world doesn't have anything like enough vaccine manufacturing capacity to meet the need. According to the Economist:
"[The world's] entire capacity for flu-vaccine production is only 300m shots a year (each containing 15 micrograms of the active ingredient known as antigen). Yet in the case of superflu, several billion people would need vaccination—and they may need two shots at higher doses."
And about those higher doses: as the Economist noted, normal flu vaccines deliver 15 micrograms of antigen. According to the study that showed results from a vaccine against H5N1, it takes two shots with 90 micrograms each to produce (what we hope is) an immune response capable of conferring protection against the virus. Since that's twelve times the normal amount of antigen per person, and since producing antigen is what limits our capacity to produce vaccines, our global flu vaccine capacity, if devoted entirely to producing avian flu vaccine, would be able to produce only enough vaccine for 25 million people. In the world.
As far as the US is concerned, Nature reports: "If the entire US vaccine production system, which can produce 180 million seasonal flu vaccines, was devoted entirely to making pandemic vaccine at this concentration, it could make enough for 15 million people: barely 5% of the US population."
And that's assuming that any vaccine produced in the US is used in the US. Most people I've read assume that this is true: that if a pandemic strikes, countries with the capacity to produce vaccines will use those vaccines for their own populations. Quoting the Economist again:
"Most of the world's flu vaccine is produced in nine countries: Australia, Britain, Canada, France, Germany, Italy, Japan, the Netherlands and the United States. Europe produces 70% of the vaccines. And Europe's vaccine producers are worried. Without international agreements now, they say there is a high risk of inadequate, inequitable and delayed supplies of vaccines. Among public-health officials and vaccine manufacturers, there is a widespread assumption that, during an outbreak, countries with production facilities would declare a national emergency and limit or ban the export of vaccine to other countries. That might be good for people living in the nine countries on the list, but it would leave the rest of the world without any vaccine at all."
Bottom line: it's wonderful that we're working on a vaccine. Efforts to ramp up our vaccine production capacity, and to develop quicker ways of manufacturing vaccines, will have lots of benefits down the road. But don't count on vaccines to protect you if an avian flu pandemic hits.
Antiviral drugs: There seem to be two antiviral drugs to which H5N1 is not resistant: Tamiflu and Relenza. To quote the Fluwiki, "Most attention has been given to Tamiflu because it is a tablet, which is easy to administer consistently. Relenza, on the other hand, is more difficult to administer because proper use of a dry-powder inhaler requires some skill. It can also provoke an asthmatic attack." (Yuck.) They can be given either to protect someone who is infected, or to treat someone who has been infected; in this case, however, they must be given within 48 hours of infection, and the earlier the better. Neither cures avian flu; they just ameliorate its effects, making the actual illness weaker and shorter.
The good news is that the government has decided to stockpile Tamiflu. The bad news is that it only made this decision very recently. From the NYT:
"As concern about a flu pandemic sweeps official Washington, Congress and the Bush administration are considering spending billions to buy the influenza drug Tamiflu. But after months of delay, the United States will now have to wait in line to get the pills.
Had the administration placed a large order just a few months ago, Roche, Tamiflu's maker, could have delivered much of the supply by next year, according to sources close to the negotiations in both government and industry. As the months passed, however, other countries placed orders that largely exhausted Roche's production capacity this year and next.
Democrats on Capitol Hill are complaining that the delay has put Americans in jeopardy. "The administration has just drug its feet through this whole process," said Senator Tom Harkin, Democrat of Iowa, who has pressed for legislation to buy more courses of Tamiflu. A course includes enough pills for a full treatment. Senator Barack Obama, Democrat of Illinois, said in an interview that Michael O. Leavitt, the secretary of health and human services, told senators in a closed-door briefing last week that the administration would soon place an order to raise the government's Tamiflu stockpile to 81 million courses - up from 12 million to 13 million courses expected by the end of 2006. Mr. Obama has long been urging the government to buy more Tamiflu.
"Secretary Leavitt admitted that they are currently in negotiations with Roche to try to rapidly build up those stockpiles," Mr. Obama said. "But we're behind countries like Great Britain, France and Japan, and it's probably going to cost us a lot more money than it would have to catch up." (...)
Dr. Irwin Redlener, director of the National Center for Disaster Preparedness at Columbia University, is among those who have been insisting for months that the government buy more Tamiflu. But he said the Bush administration largely ignored his and others' warnings. "And now that they're finally worked up about it, the store is closed," Dr. Redlener said, referring to Roche's supply problems. "The U.S. is now in line behind much of the rest of the world."
Terence Hurley, a Roche spokesman, said that 40 countries had ordered Tamiflu to fill medical stockpiles in case of a pandemic. Many countries in Europe - including France, Britain, Finland, Norway and Switzerland - have ordered enough to treat 20 percent to 40 percent of their populations. The American stockpile would treat less than 2 percent of the population. (...)
The government and industry officials, however, said that Roche had committed to delivering seven million courses to the United States next year and would not be able to deliver substantially more until 2007."
Bottom line: if an avian flu pandemic strikes in the next two years, I wouldn't count on the US having enough Tamiflu to protect more than a small proportion of the population.
As I said, I think we deserve credit for our work on vaccines. But our failure to move more quickly on Tamiflu is inexplicable. H5N1 has been getting more and more ominous for about two years now. During those two years, public health people have been saying that we do not have the resources to protect people, and urging the government to stockpile antivirals. The fact that we are only now doing so is something we should be ashamed of. If a pandemic strikes, it will cost people their lives.
The FluWiki's page on Medical therapy has a good discussion of this topic, including how to treat symptoms, and secondary infections. It's very much worth a look.