With new COVID variant-specific booster shots set to roll out in the coming week, vaccine scientists argue that more research is needed to understand how a person’s early immune response — either through vaccination or infection itself — may impact future protection against a constantly evolving virus.

The body learns its best defensive moves during its first encounter with a virus, according to experts. However, once a virus evolves, the immune system is slower to respond.

That is a phenomenon called “original antigenic sin,” or “immune imprinting.”

Scientists say that despite nearly three years of living amid pandemic there are unanswered questions. For example: What’s the best way to maximize protection through vaccination? What vaccine formula would deliver the broadest immune coverage? How often should people receive booster shots?

The answers would help public health authorities decide future vaccination strategies such as the vaccine’s formula and when doses are administered.