One of the greatest success stories of the pandemic has been the development of mRNA vaccines. However, 2 years into the pandemic, many people’s immune systems are no longer naive to the virus, which has led to questions about how vaccines could and should evolve in the future.

Without this information, it was difficult to evaluate how much of the protection discovered in the trial was due to the vaccine or to previous exposure to the virus. This presented some challenges.

In fact, in areas heavily impacted by the virus in the first wave, the requirement to recruit participants with no previous infection was met with some initial reactions of disbelief.

Read More:  https://www.medicalnewstoday.com/articles/what-immune-imprinting-means-for-the-future-of-covid-19-vaccines