Why do we need improved vaccines?

Vaccines teach the human defense system how new pathogens look like, so you are trained to combat them before you actually meet the bug and have to learn it the hard way.

Through vaccination, disease can be prevented, thereby positively affecting:

  • Health (prevents sickness and death)

  • Economy (prevents increased health care costs and costs of missed working days)

  • Currently we need new vaccines each year, because:

    Every year, it has to be analyzed which changes have happened in the influenza virus and what the vaccine for that year should look like. However, production of the vaccine takes several months and in the meantime the virus continues changing. Sometimes that means that the vaccine cannot protect you from a strain that is very prevalent by the time the vaccines are produced.

    In addition, if the vaccine has a good match that year, still the protection is waning . Over time, your defense system will lose the ability to adequately fight the influenza virus it was trained to kill. However, a low level of immunity exists.

    The virus is changing and is not recognized anymore by your defense system:

    Currently, a vaccine typically contains 4 strains of the influenza virus family and after vaccination your defense system will be able to recognize the strains that were present in the vaccine, but not others. Since influenza can multiply fast and with each generation new changes can be introduced, the virus undergoes many changes and after one year our defense system can hardly recognize the changed virus. Therefore, a new vaccine is needed to protect from the changed virus.

  • We do not know what the virus (whether influenza or another one) that will cause a pandemic will look like.

    Whether a virus will have pandemic potential depends on the level of recognition by our defense system in the population as a whole and how fast it can spread in humans. The impact depends on the severity of the disease: if the virus is mild, it still can have large economic effects, but if it causes severe disease and death, it can have an enormous impact.

    The same subtle changes that cause seasonal epidemics also happen in birds. These viruses normally cannot infect humans, with some exceptions:

    Though rare, the sum of many changes together can make the virus able to infect humans. When this virus jumps to humans it cannot be recognized by humans.

    Some mammals are more easily infected with bird viruses than humans and if that happens the virus will adopt to mammals. This will increase the likelihood the virus acquires the ability to infect humans.

    If a virus that causes disease in humans, and a virus that causes disease in birds both infect an animal that can be infected by both viruses (such as a pig) these viruses present in the same host can quickly exchange their genetic material and new strains will emerge that have very different characteristics.