How Safe are Subunit Vaccines?

Subunit vaccines were developed as a safer means of immunising against disease. While other vaccines are carefully evaluated for their safety and efficacy, there are some concerns about their use which are addressed by subunit vaccines. In this article we look at a couple of these concerns and how subunit vaccines address them to form a safer immunisation technology.


Reversion is a concern when it comes to using live vaccines. These are a very effective immunisation technique as a whole, live version of a pathogen is used to immunise a person. This version of the pathogen is carefully grown in such a way that it is weakened or attenuated, and can’t pose a serious health risk. Because the attenuated pathogen mimics the action of the actual disease, this type of vaccination can provide strong and lasting immunity quickly and efficiently.

One of the risks it carries is that of reversion. This is the term used to describe an event during which an attenuated pathogen undergoes a genetic change that renders it more dangerous to the human population. If this were to occur, the person receiving the vaccination would suffer an actual infection.

Subunit vaccines carry no risk of reversion because structural fragments of a pathogen are used to get the body to trigger an immune response. This means that there is no chance of an actual infection of any kind.

Safety of at-risk groups

At-risk groups are those that can’t safely undertake live vaccination, and they include people aged 65 and above and pregnant women. Even the attenuated strains used in a live vaccine can pose a risk to these people, which is why alternatives, like the subunit vaccine, are employed. Again because tiny fragments of the disease causing organism are used as opposed to the organism itself, these vaccines can immunise a body without exposing it to any kind of real threat, which allows for the immunisation of people who might be vulnerable to the weakened viruses and bacteria of live vaccines.

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