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Differences between vaccinovigilance and pharmacovigilance

The objectives and processes of pharmacovigilance are similar for vaccines and other types of medicinal products, however, vaccinovigilance is different from vigilance for drugs in many ways. Vaccine-specific aspects and unique challenges should be considered when designing and implementing pharmacovigilance activities for vaccines. This blog post will try to review some of the key differences between vaccinovigilance and pharmacovigilance.

The fundamental difference between drugs and vaccines is that drugs are usually used in symptomatic individuals as an intervention to treat an existing illness or condition. In contrast, vaccines are generally administered to otherwise healthy individuals to prevent disease. This material difference between intervention versus prevention affects the entire analysis, interpretation, and implications of pharmacovigilance data.

Firstly, the window for an acceptable safety profile of vaccines is narrower compared to drugs. The target population of vaccines are otherwise healthy individuals, often very young or vulnerable. Furthermore, vaccination is mandatory in some countries and vaccines are most often administered to large fractions of the population. Therefore, a high level of safety is required and the and tolerance to risk in vacciness is usually low.

Moreover, assessing the causality between adverse events and vaccines may be more difficult. People receiving vaccines are usually healthy. Therefore, since no other symptoms or interventions are concurrent, it is easier to attribute the temporal symptoms associated with vaccination to the vaccine as the causal agent (e.g. fever, swelling, pain, glandular enlargements).

On the other hand – vaccines have a short duration of exposure with a lengthy response duration, whereas drugs usually have a more extended period of exposure with a shorter response time. Thus if any event occurs in the long-term, it may be falsely attributed to the vaccine because no other causality is observed. And vice versa – it may be problematic to attribute a delayed event since the patient may have experienced many other exposures, events and treatments since the time the vaccine was administered.

Lastly, determination of the causality of adverse events and vaccines is particularly challenging since considerations of dechallenge and rechallenge are not relevant to most of vaccines.

Another notable difference between vaccine-related adverse events and those associated with drugs is that vaccine-related adverse events are usually immunologic and signal an immune response. And since vaccine’s aim to elicit an immune response on a target antigen, the emergence of such immune or inflammatory reaction can indicate the desirable immune response and not necessarily an adverse event. In drugs on the other hand, drug-related toxicity almost invariably indicates an undesirable effect.

About us. Insuvia is a specialized drug safety and pharmacovigilance service provider capable of supporting clinical trial safety and post-approval pharmacovigilance globally and locally in more than 50 countries. We have comprehensive expertise in pharmacovigilance of all product classes, such as biologicals, vaccines, advanced therapy medicinal products, small molecules, orphan medicines, and others. Find out how Insuvia could help your organization streamline PV activities by contacting us via any of the contact forms on our website.

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