Baxter H5N1 Vaccine News
Baxter released news that its experimental human H5N1 vaccine based on an Indonesian clade of H5N1 recovered from a human victim showed effectiveness. While good news the vaccine issue is multi-layered and not addressed simply with the success of a version of vaccine.
This from Bloomberg.com:
Baxter Vaccine Works for Indonesian Bird Flu in Study (Update2)
By Simeon Bennett
Nov. 16 (Bloomberg) -- Baxter International Inc. said its trial vaccine against an Indonesian variety of avian influenza was safe and effective in a human study, the first time a vaccine has been developed against the deadliest strain.
Findings released today showed the experimental vaccine, derived from an Indonesian victim who died after infection with the strain of H5N1 bird flu in 2005, induced protection in more than 90 percent of healthy volunteers even at the lowest dose. The vaccine will probably also protect against other Indonesian strains of the virus that together have caused the most deaths, said Hartmut Ehrlich, vice president of global research and development for Baxter's bioscience unit.
The Bloomberg article notes that the Indonesian strain is the "deadliest strain", that designation is well deserved. The cumulative CFR (Case Fatality Ratio) for WHO confirmed Indonesian human H5N1 infections is currently at 80.5%, while the world-wide cumulative CFR is 61.5%.
The following chart is from WHO.org (12Nov07).
Should we consider only the 2007 cases, the CFR for Indonesia would be 87% (rounded) and 66% for all 2007 WHO confirmed cases, a significant difference. It is that significant difference that drives the critical need for Indonesian samples that I have a tendency to get so het up about.
But to the point of this entry:
Human H5N1 vaccine takes two doses: an initial "priming" vaccine, with a follow-up vaccination 28 days later; the Baxter human H5N1 Indonesian strain vaccine the Bloomberg piece is about is a two-dose vaccine.
The fine print of the two-dose set up is that the first dose, by itself, is proving to be very poor at producing immunogenicity, and must be followed with the all important second dose. All told, it is approximately 6 weeks until the vaccine offers what is classified as protective immunogenicity—six weeks.
An infectious disease modeling paper came out a few days ago:
14 Nov 2007
A new approach to simulate the transmission of infectious diseases, such as avian influenza, between people has been published in the Journal of the Royal Society Interface today (Wednesday 14 November 2007).
Using novel computer modelling software, Professor Yang and his team from the University of Southampton, have modelled the spread of a hypothetical disease outbreak across the city of Eemnes, in the Netherlands. The study simulated the complex daily activities and movements of every individual in the city, to identify how their interactions spread the disease.
The paper includes this informative graph:
What this graph tells me is that even before we can give a population the all important and crucial second dose of vaccine (optimally at day 28-30) the height of the infection wave will just about be reached (roughly day 36-40), and before effective immunogenicity.
This is just one example of what makes a vaccine for pandemic influenza no magic bullet solution even without the manufacturing capacity issues. For a complete, easily understood, presentation of the issues surrounding pandemic influenza vaccine see Maryn McKenna's series The Pandemic Vaccine Puzzle on CIDRAP.
The Baxter vaccine trials news is certainly welcome, and certainly good, but we still have a great many other difficulties to address in the multilayered vaccine issue and we mustn't let good news distract us from our continued difficulties.
Let this be understood, then, at starting; that the patient conquest of difficulties which rise in the regular and legitimate channels of business and enterprise is not only essential in securing the success which you seek but it is essential to that preparation of your mind, requisite for the enjoyment of your successes, and for retaining them when gained. So, day by day, and week by week; so month after month, and year after year, work on, and in that progress gain in strength and symmetry, and nerve and knowledge, that when success, patiently and bravely worked for, shall come, it may find you prepared to receive it and keep it.
Josiah Gilbert Holland
And so we work on.
SZ
Novavax, Inc. is developing tomorrow’s vaccines today that include a superior product to Baxter’s bird flu vaccine IMO.
Novavax is focused on creating novel, highly potent recombinant vaccines produced via cell culture Virus-Like Particles using its proprietary virus-like particle (VLP) technology, Novavax scientists build a structure similar to a virus except for the genetic material required for viral replication. Once injected into the body, VLPs attach to cells and trigger an immune response sufficient enough to protect a person, if they are exposed to the virus.
VLPs may have a number of advantages over traditional vaccines. Because they more closely match an individual viral strain, VLPs can trigger a more robust immune response. In addition, live virus is not needed to produce a VLP vaccine. Rather, Novavax scientists need only the genetic sequence of a virus to quickly create a VLP vaccine against it. Because VLPs do not contain viral nucleic acids (DNA or RNA), they cannot replicate, and therefore present no threat of infection to a person being vaccinated. http://www.novavax.com/
Novavax’s vaccines are grown in insect cells and manufactured using an innovative system that is both portable and disposable. Novavax’s modular system is designed to be delivered, installed and put into use quickly in an approved manufacturing space anywhere in the world. And because much of this equipment is disposable, operating costs would be significantly lower than those associated with traditional manufacturing methods. http://www.novavax.com/go.cfm?do=Page.View&pid=4
http://www.novavax.com/go.cfm?do=Page.View&pid=4
Posted by: Isabella4907Quoi | November 18, 2007 at 11:29 PM