Live Bird Flu Vaccines In Testing Trials
September 7th, 2008

A heightened level of awareness and concern has arisen from recent outbreaks of the highly pathogenic avian influenza, or bird flu, in Asia. Human infections associated with this virus have led scientists and researchers to begin work on a vaccination to help in the case of a possible influenza pandemic. Vaccinations are the best way to prevent the spread of the influenza, as well as to help lessen the severity of the virus. Such vaccines are critical in the event that the avian influenza emerges into the human population. It is important to produce live attenuated and inactivated vaccine seed viruses against avian influenza viruses, which have the potential to cause pandemics, as well as their testing in pre-clinical studies and clinical trials to help ensure that manufacturing experience exists. Studying these vaccines will also help us to understand the biology of the avian influenza virus and its behavior in mammalian hosts.

Influenza A viruses are very common in nature and can infect a variety of birds and mammals. Very few of these subtypes of influenza A virus cause sustained outbreaks of disease in humans.

Pandemics occur when an influenza strain appears and spreads in a human population, which has no immunity to the virus. Although it is not possible to predict when the next pandemic will occur, or if it will be the avian flu that will cause it, experts are forecasting that the H5N1 type A avian influenza virus could possibly be cause the next one.

Although a different virus, or strain than the highly pathogenic H5N1 AI virus, which is now circulating in Asia, could possibly cause the next influenza pandemic current vaccine development activities are mostly focused on viruses of this subtype. Experts are focusing on the challenges facing development of pandemic influenza vaccines and how a library of vaccine seed viruses can be prepared and tested.

The recent deaths in Asia, as well as the evidence that this virus has mutated and can infect the human population, underscore the need for a vaccine to thwart the potential spread of a pandemic virus and to prevent illness and death associated with this deadly strain.

Human influenza vaccines are generated to elicit protective antibodies that are directed primarily against HA, which is the antigen of the virus that causes neutralizing antibodies. Large holes still remain in the understanding of immunity to AI viruses, even though major advances have been made since human infections first were reported in 1997. It is vital to fill those holes in researcher’s understanding in order to develop vaccines capable of protecting the human population. Studies have shown that several types of inactive vaccines do a poor job of protecting against human influenza strains of this nature.

Several problems that need to be addressed include manufacturing capacity, the ability to candidate vaccines to grow well in eggs, and biological safety. Another difficulty is determining the most vulnerable sections of the population to be targeted for vaccination, since they may not be the same as with yearly influenza epidemics. This is why it is critical to use the time before the next pandemic to develop and clinically test candidate vaccines.

Intensive planning and preparation for a global influenza pandemic is underway due to recent events in Asia. Being prepared includes vaccine development, as well as the ability to manufacture this vaccine to ensure that the population can receive it. The interpandemic period must be used to explore the best scientific, manufacturing, regulatory, and clinical research strategies to develop vaccines that are effective in fighting the pandemic influenza. This will ensure that a vaccine will be available as soon as possible in the event that influenza pandemic occurs.

---

Please use the form below to comment on this page:

Name:
Email Address:	(kept private)
Comments:
Let me know if my message is replied to:	yes
Please enter the digits 513 in the box. This keeps away spam robots: