With India’s Covid-19 vaccination campaign proceeding, two terms that sound similar are prone to misinterpretation: vaccine efficacy and va...
With India’s Covid-19 vaccination campaign proceeding, two terms that sound similar are prone to misinterpretation: vaccine efficacy and vaccine effectiveness. The dictionary meanings of these terms are different from the way they are used in scientific discourse. Understanding them could help readers make informed decisions when they are getting vaccinated.
Vaccine efficacy
Many people interpret vaccine efficacy to mean the percentage of people who would not get the disease after vaccination. Sometimes, it is also interpreted as the percent of possibility that a vaccinated person would be protected from the disease. However, it is not as straightforward.
To understand vaccine efficacy, one has to first know a little bit about randomised controlled trials, a type of research design, commonly used for clinical trials – in this case, for Covid-19 vaccines. In RCTs, the study participants are randomly assigned into two comparable groups. In one, the experimental group, the actual vaccine is administered. The other, the control group, gets a placebo – a neutral, unharmful substance that is not a vaccine.
The process takes place in optimal conditions, which means that it occurs in an environment that is scientifically controlled and is similar for both experimental and control groups. If the outcome in the experimental group, in statistical terms, is...
