Although the vaccines proved to be the most important discoveries against the COVID-19 pandemic, they are getting obsolete and the fast-evolving SARS-CoV-2 variants like the Omicron sub-variant BA.4 and BA.5 are complicating vaccine updates. Although the existing vaccines seem to be holding up against severe COVID, since the vaccines are now offering only short-lived protection from infection, many scientists are in consensus that the vaccines are overdue for an upgrade.
Most of the current vaccines are designed based on the original version of the virus SARS-CoV-2, which is a poor match to current Omicron strains. Since Omicron is evolving so fast with the emergence of highly transmissible strains like BA.4 and BA.5, which are known to erode the immunity obtained from vaccination and infection with previous strains, including earlier versions of Omicron, it is making the task of vaccine upgrade very complicated.
In general, the decisions surrounding the composition of upcoming vaccines, like the examples of influenza vaccines, are based on a solid understanding of how those viruses evolve. Unfortunately, the patterns on how SARS-CoV-2 could evolve in the future are still not well established unlike that of the seasonal flu where the rules have been successfully predicting the evolution pattern.
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