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Biotech / Medical : SARS and Avian Flu -- Ignore unavailable to you. Want to Upgrade?

To: Andrew who wrote (1820)	11/28/2004 5:58:01 PM
From: Henry Niman	Respond to of 4232

Here's a summary I wrote up elsewhere: The are two distinct flu vaccines. One is the trivalent vaccine that is in short supply. The other is the pandemic vaccine, which has yet to enter clinical trials and is projected to be ready in 2007 assuming there are no problems and the virus doesn't change (two VERY unlikely assumptions). There are problems with the trivalent vaccine, because it seems unlikely that Chiron will have its Liverpool plant available for 2005. I think that next year's trivalent vaccine gets going in March for the northern hemisphere. Since Chiron had cerratia contamination in 2001, 2002, 2003, and 2004, it seems that the bug will keep the plant closed for 2005. Two companies, Chiron and Aventis, are working on pandemic strains. Chiron is working on H9N2 and it is being developed in another Liverpool plant, which is being inspected. Aventis is working on H5N1 and is expected to begin trials in early 2005. These two serotpes are known to reassort, but they also recombine recombinomics.com Right now all of the vaccine in preparation use the same technologies. The H and N of the selected strain is added (by reverse genetics) to a background of the other 6 genes and the reassorted virus is grown in chicken eggs, harvested, killed, and combined for injection. The trivalent vaccine has 1 Influenza B and 2 influeza A strains. The A includes 1 H1N1 serotype and 1 H3N2 serotype. Lately the H3N2 serotype has beem causing the most severe disease and has created the most controversy. The vaccine changes (drifts) frequently because the virus changes (by recombination but scientists think its by mutation) recombinomics.com Frequently a new virus that shows up at the end of one season becomes dominant the next season. At the end of 2002, and new varient of H3N2, Fujian, began to appear in Asia and by the beginning of 2003 was worldwide. The recommendation was made that the H3N2 component of the 2003 vaccine be changed from Panama, which had been around since 1999, to Fujian. However, there were problems growing Fujian in chicken eggs without first passaging it once in tissue culture, but the FDA balked at that, and manufacturers said that changing to Fujian could endanger the entire vaccine (because all 3 viruses are given in a single shot). Consequently, Panama was used for 2003 and many children died (but since no one was tracking children's deaths previously, it wasn't clear how significant the number of deaths were). This year the vaccine contains Fujian and so far all H3N2 isolates that have been typed are Fujian-like (last year it was 80-90% Fujian, the rest Panama). However, Fujian has changed and the H3N2 being prepared for the 2005 vaccine for the southern hemisphere has Wellington replacing Fujian (and Wellington or a Wellington varient will probably be used in the 2005/2006 vaccine for the northern hemisphere). However, without Chiron, other manufacturers will have to fill the void, which could be large because before the vaccine shortage the CDC was recommending the flu shot for those 50 and over (which includes a lot of baby boomers) and there is talk of recommending a shot for everyone (because even though the healthiest don't die from flu, they infect vulnerable populations who do die and the number of hospitalizations and deaths are on the rise (although the data are old, only going through 1999, but its probably worse because of an aging baby boomer population). As you can see from the above, there are a number of issues with the human flu vaccine. WHO has talked about immunizing the world (6 billion) against a pandemic strain, and their latest numbers (which are very conservative), talk about 7 million deaths worldwide from a H5N1 pandemic recombinomics.com

To: Andrew who wrote (1820)	11/28/2004 6:02:13 PM
From: Henry Niman	Respond to of 4232

Part of the time lag for a pandemic vaccine is the fact that it hasn't been approved. Thus the delay is due to clinical trials. A vaccine for injecting will probably be ready in a few months (sometime in January), but scaling that material up would take several months, and scaling it up to billions of doses would take even longer (I think that worldwide there are 300 million doses of human flu vaccine made each year).