Category Archives: TIV (flu)

Trivalent influenza vaccination

Is this years H1N1 vaccine rushed without adequate trials?

The basic make up of the H1N1 vaccine is no different from the influenza vaccine we receive every year. Same parts, same process, same packaging and the same delivery.

What is different is that combination of antigens that are present in H1N1 are novel, new and unique.

H1N1 appeared on the scene too late after the seasonal influenza constituents were agreed upon in this years vaccine. Plus it was too late to include it in the seasonal vaccine process, therefore a separate vaccine was added.

What makes the vaccine different is its antigenic structure. An analogy for this may be to think of the virus as having a lock on it. The vaccine gives us the right key to unlock the virus and hence kill it. H1N1 was sneaky this time around and changed to tumblers (the antigens) in the lock to something we never had to encounter before. Same virus with same basic biological structure, same inner workings, infecting the same cells, multiplying in the same way and killing in the same way, just using a different code. So rather than use one of the known “keys” we already have on our keychain that worked for the influenza “lock” in the past, we had to come up with a new key (vaccine antigens) to work with the H1N1 lock combination. Remember same kind of lock (virus target), same material for the key (vaccine), same keyhole (targets of the vaccine), just different key pins (the antigens).

Therefore the side effect profile, route of administration, efficacy and safety should be about the same as traditional influenza vaccination.

Shame on you H1N1 for trying to pull a fast one on us this time. Fool me once (in 1918) shame on you, fool me twice shame on me.

For more information on the new H1N1 vaccine see the CDC website.

Why do we need to be vaccinated against influenza every year when other diseases do not?- updated 10/23/09

There are two basic kinds of viruses, those that are made of DNA, the stuff we are made of and RNA viruses. These are viruses that contain a more primitive form of genes.

DNA tends to more stable and reliable from generation to generation. Hepatitis B and Small Pox are examples of DNA viruses.

Influenza on the other hand is an RNA virus and a very unstable RNA virus when compared to other RNA viruses. When it invades a host cell it creates million of copies of itself. In the process it kills the host cell. But because RNA virus have poor error checking due to the lack of a proofreading enzyme called DNA polymerase the copies of itself are very sloppy. Over 80% of these copies are unusable and are not infectious. The remaining ones are infectious to other cells but are still not exact copies of the mother virus. They are therefore “quasi-species” that is; they are very similar but not exact. Over time the virus gradually changes in its genetic makeup.

Our immune system recognizes an invader as alien by its genetics. The specific site on the virus that our antibodies recognize is called the “epitope”. If the genetics of the virus change too much i.e. change the epitope then our immune system takes longer to get into action, sometimes too late. If our immune system has been primed to recognize the viruses epitope from recent experience like a vaccination which is exposing that epitope to our antibody factory. This is akin to getting the floor plans. Then our immune system will shift into high gear much quicker because of the headstart. Hence the need for revaccination every year with a virus that is as close to the current strain as possible.

Plus the antibodies that we do make do not stay around in ample supply forever. In the case on Influenza the antibodies last about 4-5 months. This is also why the sickest people should not get vaccinated too soon before the season. After october 1st is generally a good time to get vaccinated that way we can face the influenza season with the optimal quality and quantity of antibodies.