Real-World Evidence and Vaccine Effectiveness Explained

When it comes to understanding how well a medicine or vaccine works, it can feel like there’s a lot to take in. In this article, we explain two key types of evidence – clinical trial data and real-world evidence – what they are, why they’re important and how to interpret them.


What is the difference between efficacy and effectiveness for a medicine or vaccine?

A clinical trial is a carefully controlled research study, designed to establish the effect of a medical treatment and how well it works – its efficacy – by assigning people to different treatment groups. These trials are an essential part of the medicine evaluation and approval process, but they aren’t without their limitations. 

The highly controlled environment of a clinical trial may not always reflect what happens in everyday practice.

Real-world evidence is one way of addressing questions about a medicine or vaccine that remain unanswered after it has been studied in a clinical trial. Real-world evidence is collected as part of day-to-day healthcare practice and reflects routine clinical experience across a larger and more diverse population.

In combination with clinical trials, real-world evidence helps to build a “bigger picture” of the effectiveness of a medicine or vaccine is in the real-world setting.


Efficacy vs Effectiveness


Why is real-world evidence important for learning about the effectiveness of COVID-19 vaccines?

In the case of COVID-19, real-world evidence helps to demonstrate the contribution vaccines are making to help manage the pandemic. It is vital in helping governments, health care providers and communities understand how effective vaccines are at reducing the burden of, and protecting against, COVID-19.

Specifically, real-world evidence can help us understand vaccine effectiveness:

• against different disease severities - from reducing deaths and hospital admissions to preventing milder forms of the disease

• in reducing rates of infection across the population

• in preventing transmission and spread of the virus

• in different populations, including age, race, ethnicity and those living with underlying health conditions, such as asthma, diabetes and HIV

Whilst important, it is difficult to compare real-world evidence as it is captured at different times, in different populations, in different places that may have different levels of COVID-19 infection and with different variants of the virus in circulation. 


Delivering powerful insights to improve public health strategies

To overcome COVID-19, many different vaccines, other treatment options and social measures may be needed to support long-term immunity and protection against new variants as they arise. Real-world evidence can help to improve our knowledge and understanding, and support strategies that can help protect lives, reduce the rate of infection and drive down hospitalisation rates.



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