Immunisation remains a globally cost-effective method for reducing disability, disease and death. But researchers face the constant challenge of increasing both vaccine safety and efficacy. A challenge also seen in parental hesitancy towards child immunisation.
New research has found a way to combat both these aspects: by making the highest efficacy type, live attenuated vaccines, even safer.
White blood cell memory
Vaccines work by introducing a small dose of a disease-causing pathogen (usually viruses or bacteria) to create a memorable immune response.
Upon detecting pathogenic invasion, various types of white blood cells will act. Some work like experienced soldiers — directly battling the pathogen. Others act like soldiers in training — remembering the pathogen to be ready to battle if re-invasion occurs.
For viruses, how well the training soldier cell recalls is dependent on what form we deliver the virus in.
The efficacy and safety trade-off
Inactivated and live attenuated vaccines are the two main forms of virus delivery.
Inactivated vaccines have lower efficacy in inducing a memory response as the vaccine only includes part of the virus or its dead form. It’s hard to know who to battle by only recalling parts of them. But it’s also a safer vaccine as the virus cannot replicate to actually cause the disease.
In live attenuated vaccines, the virus is in its full living form, inducing a higher efficacy memory response. However, this poses the risk of the virus replicating.
Past methods to remedy this involved replicating the virus in harsh conditions to make it weaker — but that replicating potential still exists.
This new research is revolutionary in altering the genetic blueprint of the influenza (common flu) virus, making it unable to replicate.
A series of different codes make up the blueprint for replication in all organisms. When the replicating machinery analyses these codes, the code order ensures exact selection of the same proteins that make up the organism.
Certain blueprint codes stop the replication process when the machinery analyses it. By altering existing codes into such codes, the replication process terminates prematurely. The virus can’t successfully replicate, making a safer live attenuated vaccine possible.
The future of immunisation
While the research requires further testing, researchers are confident we can adapt such methodology for all kinds of pathogens causing diseases.
When faced with the choice of immunising ourselves and people in our care, we no longer have to compromise. A safer, higher efficacy vaccine will exist.