bird flu
revere | April 18, 2007I wasn't going to post on the announcement yesterday by the US FDA that it had approved the Sanofi Pasteur H5N1 vaccine. We've discussed it before. It was pretty much a failure, requiring too much viral antigen, two doses, and resulting in putative protection of less than half of those who receive it. There is a stockpile (or will be) of about 3 million doses in the national stockpile, only enough for a tiny fraction of those who would need it, with doubtful value for many of them. It was approved because, like the crooked gambling wheel, it's the only game in town. Who would get it isn't…
revere | April 17, 2007Some reporters are so good it just makes your head shake when you read them. In the flu world, the prize (always) goes to Helen Branswell of Canadian Press. She's not a stylish writer, just an exceptionally clear one. Her sources are the best and her reporting as reliable as her sources are good. My RSS reader seems to miss some of her stories, but when I get them they are usually head and shoulders above the competition. And sometimes there's no competition. Like her interview with Dr. Keiji Fukuda, head of the WHO's global influenza program.
In it we learn that China is still not producing…
revere | April 16, 2007I admit it's a paradox, but I can't help myself. Whenever I hear that a high government official has debunked claims of a human case of bird flu, my first thought: "Oh, shit. Another case."
The minister of information and communications, Frank Nweke Jnr., has debunked claims that there was any other human case of avian influenza reported in Nigeria since the beginning of the year.
The minister, quoted in a news bulletin from the Avian Influenza Crisis Management Centre, Abuja, and released on Thursday, noted that the "multi-Sectoral Steering Committee on the Management of Avian Influenza in…
revere | April 14, 2007When we consider the spread of bird flu, we often focus on the basic reproductive number, R0, the average number of new cases that a single infected individual would produce in a completely susceptible population. But individuals are not the only possible unit of analysis. One could consider infected farms, too. That's what researchers at Imperial College London and the London School of Hygiene and Tropical Medicine did in their analysis of the spread of the H7 subtype (H7N3, H7N7, H7N1) of avian influenza virus in Italy, the Netherlands and Canada. The results of several years of data showed…
revere | April 13, 2007I admit to being prejudiced, here, but my experience living in Sweden (a long time ago, it is true), knowing a bit of the language and seeing what goes on there makes me think of the Swedes as one of the most rational people on earth. It's true most other peoples don't give them a lot of competition on that score, and I am sure there will be Swedes reading this who will protest I've done their country an injustice. It's far worse than I'm making out, they'll tell me. Sure. Come over here and live. Don't forget to bring your Swedish health insurance. We don't provide it here.
Sweden is a small…
revere | April 12, 2007The newswires are on it again. This one has a good hook. A flu vaccine made in insect cells. So I read the paper. And in truth, it's pretty interesting.
Genetically engineered flu vaccine made from yellow striped caterpillars instead of hen eggs has been shown for the first time to keep people from getting the flu, scientists say.
The results are preliminary but suggest the insect method could be a quicker, easier alternative to the lengthy, antiquated egg-based procedure now used and could lead to a more rapid response to a pandemic, the study authors say. (Lindsey Tanner, AP)
There's more…
revere | April 11, 2007The newswires are carrying a story that the journal, Chest, is about to publish a retrospective study of influenza mortality and statin use. As happens more and more frequently, press reports are appearing prior to the actual article, so I haven't read it yet. This is very irritating. The whole press embargo system is irritating, in fact, and should be deep-sixed (Full discolosure: I frequently get advance copies of embargoed articles and I honor the dates. But I don't think journals should do it. It serves no useful purpose.).
The embargo issue aside, here is what the press is saying:…
revere | April 10, 2007Several readers have pointed me to an online piece on face masks and ultraviolet light as influenza control measures just published in the American Journal of Public Health. Both are presented as a Plan B in the (lkely) event Plan A's vaccine and sufficient or sensitive antivirals are unavailable. The review by Weiss, Weiss Weiss and Weiss (I know a joke that goes like this, but this isn't a joke) is measured an informative. First, face masks.
The authors point out that cloth surgical masks protect other people from you, not you from them. They discuss N95 and N100 respirators and provide…
revere | April 9, 2007A trip with Mrs. R. to buy something for the kitchen doesn't seem to have much to do with influenza virology, but let me try to make the connection. We're at Williams Sonoma. I'm wandering around, idly looking at various pieces of kitchen equipment and thinking random food thoughts. I'm not looking for anything particular, myself. But as I'm cruising by a set of shelves I see it has books on it. Quite a few of them. All about food and cooking and associated subjects, but books. I stop. I start to browse. Fifteen minutes later Mrs. R. retrieves me. She is going to shop for something else. I…
revere | April 7, 2007For some reason the subject of masks evokes great emotion here. I'm not sure why. The idea that masks will help in a pandemic is a strongly held belief that might even be true. We don't know. I venture into mask territory knowing that, like gun control and atheism, I'll get a reaction. But a recent paper in the CDC journal, Emerging Infectious Diseases, brings up once again the difficulties in proper mask use. The subject was N95 Full Face (FF) respirators, the kind you would need in an influenza pandemic if you were to cover your mouth, nose and eyes, the latter because you can be infected…
revere | April 5, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
This is the last in a long series attempting to explain a recent paper by Lipsitch et al. on mathematical modeling of the effects on influenza control of antiviral resistance, published in PLoS Medicine in January 2007. Modeling is a valuable technique but for most readers, even most scientists…
revere | April 5, 2007Bird flu is spreading in poultry in Bangladesh. And Kuwait has had bird flu in its poultry but is hoping its cull of 1.7 million birds has stopped it. But not until four Bangladeshis working on the cull were hospitalized with possible bird flu infection. Isolation was undertaken because of blood tests. The Kuwaiti cullers are said to have received prophylactic Tamiflu and these workers were not reporting symptoms, but "preliminary tests" were positive (via crof's blog). More definitive tests are to come:
Preliminary tests for bird flu were positive on four Bangladeshi workers who had been…
revere | April 4, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
We have now gone through the entire paper on modeling the impact of antiviral resistance in an influenza control program, by Lipsitch et al., published in PLoS Medicine. Since a number of assumptions were made, we take some time to consider what effects they have on the model's results. In the…
revere | April 4, 2007Just as we are preparing to wind up our marathon series of posts on a mathematical model of antiviral resistance, a new paper has appeared in the Journal of the American Medical Association (JAMA) with data on antiviral resistance from Japan, the country that uses more Tamiflu and Relenza (the two available neuraminiase inhibitor antiviral drugs) than any other. It turns out the accompanying Editorial in JAMA specifically mentions the modeling paper and its results as a key to understanding the significance of this work. So all our labor has not been in vain. Here's more.
Our eye was caught…
revere | April 3, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
We conclude our section by section examination of the mathematical modeling paper by Lipsitch et al., published in PLoS Medicine. We have finally arrived at the final section, Discussion (starting on page 8 of the .pdf version). In the second post we said many scientists read only the Abstract,…
revere | April 2, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
In this post we explain the remaining results presented in the paper by Lipsitch et al. in published in PLoS Medicine (the subsections headed, "Effects of resistance on epidemic size" and "Dependence of outcomes o fitness cost and intensity of control" on page 6).
These sections and the…
revere | April 1, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
We now take a look at what happens in the model when we vary the intensity of prophylaxis and treatment. The model treats the fraction of those prophylaxed, fp, and those treated, fT, separately, but for illustrative purposes the paper sets these two figures at the same number. In the previous…
revere | March 31, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
We've spent a long time in the previous posts looking inside the black box of a mathematical model for the spread and consequences of antiviral resistance to Tamiflu (described in the paper by Lipsitch et al., published in PLoS Medicine). From the last post you will recall the authors assume it…
revere | March 30, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
Now we are almost ready to run the model described in the paper, "Antiviral resistance and the control of pandemic influenza," by Lipsitch et al., published in PLoS Medicine. If you have been following up to this point, you will know the model described in the Methods section is a homogeneous…
revere | March 29, 2007[A series of posts explaining a paper on the mathematical modeling of the spread of antiviral resistance. Links to other posts in the series by clicking tags, "Math model series" or "Antiviral model series" under Categories, left sidebar. Preliminary post here. Table of contents at end of this post.]
In the previous posts we have walked through the Introduction and Methods sections of the paper, "Antiviral resistance and the control of pandemic influenza," by Lipsitch et al., published in PLoS Medicine. The Methods section sets out the detailed model, which is summarized in the Figure in the…