How Effective are Inactivated Vaccines

Killed or inactivated vaccines are a big component of modern immunisation programmes, offering a safe method of immunising people of all ages against potent disease causing pathogens. In this article we look at the effectiveness of this particular vaccination technology when compared to other methods of vaccination.

The effectiveness of inactivated vaccines

An inactivated vaccine is made up of pathogens that have been grown and killed in dedicated laboratory facilities. This makes them an extremely safe method of immunising people of all ages, and it also means that more physically vulnerable populations like pregnant women can safely receive vaccines if needed.

Inactivated vaccines are very reliable, which is why they are used as part of a number of vaccination programmes to immunise against serious conditions like cholera, typhoid, and polio. Despite being dead, the pathogens used in inactivated vaccines still possess characteristics which trigger the body’s immune response, and thereby achieve the goal of the immunisation process.

All pathogens possess unique surface molecules that our body is able to identify. These are called PAMPs, or Pathogen Associated Molecular Patterns, which act as a trigger, informing the immune system that these are invading organisms that need to be dealt with. Ultimately the presence of PAMPs triggers a cascade of different immune responses, including the development of an immune memory particular to the disease in question. This immune memory is comprised of a special class of memory cells which remain in your body, ready to act quickly should you encounter further infection.

While effective and extremely safe, inactivated vaccines do also have their own limitations. An inactivated vaccine triggers an immune response, but this is typically less long lasting than the response triggered by live vaccines, which are made up of living, albeit weakened (attenuated), pathogens. What this means in practical terms is that multiple booster shots are often needed to effectively top up the immunity offered by these injections.

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