Archive for November, 2010

Future flu vaccines

Friday, November 26th, 2010

Although the influenza vaccine we use today is safe and effective, the way we make it is basically 50 years old. We still make this vaccine the same way we did during the Eisenhower years because it is so safe and effective, and the pharmaceutical industry and the FDA are extremely conservative. Drug companies still make money on flu vaccines and the FDA enjoys a low rate of side effects in people who take it, so why change a good thing?

We should update our flu vaccine production methods because the old methods are simply not good enough. It takes about 6 months to make a flu vaccine from start, through production and testing, to finished product. That is just too long. The H1N1 pandemic showed that new influenza strains can arise quickly and we need to make vaccines against them quickly. We now make a new vaccine every year, and that may not be the best approach. A recent article in The New England Journal of Medicine shows why the old technology is inadequate and why new technology should be used.

We make our current flu vaccine in chicken eggs because most strains of the virus grow in eggs. An influenza vaccine plant is actually a big chicken farm with a small drug laboratory next to it. Our vaccine production capacity is limited by the number of eggs we can get at the time we need them; a pretty strange situation if you think about it. Each influenza virus grows in eggs differently, so the process is inherently variable.

We make most other drugs through a manufacturing process that is fast and that we can control. We can grow the virus in other cells or we can produce the vaccine synthetically without eggs. Both of these methods would be faster and less variable than our current method.

Our current vaccines contain two virus proteins, called H and N, which change every year. Investigational vaccines use other proteins that are more stable, so we may some day have a universal flu vaccine that does not have to be given every year. Maybe some day we can take a flu vaccine every 5 or 10 years, like tetanus vaccine, instead of every year.

Televisions and cars sold well in the 1950s, but they have continued to improve since then, and no one still uses those products from that era anymore. We should not be satisfied with old vaccines just because they work. We can make much better vaccines using new technology and we should invest in improving the influenza vaccine.

Flu vaccine and egg allergy

Wednesday, November 24th, 2010

Some people have allergies to chicken eggs, usually to the protein in the egg white called ovalbumin.

Current influenza vaccines are made in chicken eggs because the virus grows in them and eggs are somewht readily available. Vaccine manufacturers kill the virus and extract the virus proteins from the eggs, but a very small amount of egg ovalbumin sometimes contaminates the vaccine after it is purified.

For many years, we wondered if the small amount of egg protein in some influenza vaccines would cause a reaction in people who were allergic to eggs. There were no good studies done on this question. Many people with reported egg allergies have taken flu vaccines for years with no problems.

The drug manufacturers did not want to take any risk for such reactions, so they have always said that people with hypersensitivity to eggs should not take the influenza vaccine. That might have been a safe thing for drug manufacturers to do, but it has not been proven, and it leaves many people unprotected who may need the vaccine.

A study recently published in the Journal of Allergy and Clinical Immunology and a position paper from the American Academy of Allergy Asthma and Immunology clarify this question. Egg allergy does not pose any risk to the patient for giving the current influenza vaccines. The amount of ovalbumin in curent vaccines is extremely low; lower than the level needed to cause a reaction.

The products and guidelines for this year’s influenza vaccine and immunization programs have been produced, most of the vaccine has already been given, and things probably will not change this year. I look for the FDA and the drug manufacturers to soften their language for egg allergy next year as these new data become known.