Archive for August, 2011

New recommendations

Thursday, August 18th, 2011

The new (2011) recommendations on influenza immunization from the Advisory Committee on Immunization Practices were released today. The recommendations are not really different from last year’s, but this document includes some new information that may answer some questions people have about the topic.

This year’s vaccine is made from the same virus strains as last year’s vaccine. Some peoople have questioned whether we need to get this year’s vaccine if we got one last year. The answer is yes. Protection declines over a year, and you need another immunization this year to give you optimal protection.

The document also explains the issue of egg allergy and flu vaccines. Flu vaccines are made in chicken eggs, and a very small amount of egg can sometimes be found in the vaccine. If someone is very highly allergic to egg protein, they can have a reaction to the vaccine. This kind of allergy is very rare. Many doctors prefer not to immunize someone who says they once had a “reaction” to eggs. The guidelines clearly say that most of these people can and should get their annual flu immunization, but they may need to be observed for a little while after their dose or they should be seen by an allergist before they take the vaccine. Too many people are being excluded from protection against influenza because people don’t understand the egg connection. The recommendations include an algorithm that will help sort out the egg allergy issue.

New flu vaccines (sort of)

Wednesday, August 10th, 2011

Something new has been happening in the flu vaccine business. For about 40 years there has been just one vaccine for influenza. A trivalent (three strains) vaccine given by intramuscular injection (a shot). Although several pharmaceutical companies made vaccine, it was all nearly identical. Now we are seeing something new, although not as new as you might think.

Pharmaceutical companies are taking the same vaccine and packaging it into specialized products for special populations or markets. Economists call this market segmentation. You take a basic existing product and modify it slightly for specific groups of people to strengthen their relationship with it; make them feel like the product is just for them. The market for flu vaccine is only so big, so companies want to give people a choice and a reason to choose their product over the competitors.

Last year we saw a new high dose vaccine for seniors. Same vaccine, but packaged in a higher dose, and it has been very successful. Smart company. This year we have a new intradermal flu vaccine that avoids the long needle that so many people hate. Same vaccine but a lower dose and no scary needle. Next year we may have a flu vaccine with four strains in it instead of three. I don’t know how it will be marketed but the company will figure out a way to convince the target customers that this vaccine is just for them.

The only really new flu vaccine we have seen is the intranasal product, which is a completely different concept in vaccines.

Each of these specialized products is good for the intended customers and I think it is good that companies are trying to constantly improve their products. Just remember that the vaccine part of all flu vaccines is the same and the rest is about dose and delivery.

Universal flu vaccine

Wednesday, August 3rd, 2011

There is a news story circulating this week about the idea of a universal influenza vaccine that may not require annual booster doses. A group of scientists in the United Kingdom have developed a vaccine like this and they are testing it.

Influenza viruses change (mutate) very quickly. The parts of the virus that cause infection are molecules called proteins on the surface of the virus. Some artists picture these molecules as looking sort of like mushrooms on the virus surface, although we really don’t know exactly what they look like. The tops of these proteins cause the virus to attach to our respiratory tract and cause infection, and those parts change. We make new vaccines out of these new proteins each year as they mutate.

The people working on this project asked an interesting question. The tops of these proteins change a lot, but other parts of these proteins and other viral proteins don’t change as much. Why don’t we make a vaccine out of the parts of the proteins that don’t change so much and see if that works?

Apparently it does work. Humans develop antibodies (immunity) against these stable molecules too, and they may be protective. Maybe changing the vaccine recipe will allow us to give the vaccine less often. The interval would depend on how long our immunity lasts, not on how quickly the virus changes.

The story predicts that such a vaccine may be ready in five years. I would not count on that. If this approach seems to work, we may know how good it is in five years, but it takes a long time to test vaccines before they are approved by the FDA, and influenza is a seasonal disease, so studies can only be done during certain months of the year. It is nice to know that improved vaccines may be coming.