What results from SARS-CoV-2 producing new variants rapidly?

Evasion of pre-existing immunity derived from prior infection or vaccination

The rapid evolution of SARS-CoV-2 leads to constant antigenic drift, meaning the virus changes its surface characteristics over time. This antigenic drift directly impacts the effectiveness of acquired immunity, whether that immunity originated from a previous infection with an older strain or from vaccination. Because the immune system is designed to recognize specific structures on the virus, slight changes in these structures allow newer variants to partially or wholly evade the established immune response. This creates an ongoing dynamic where the immune system is constantly playing catch-up against succeeding iterations of the pathogen, requiring updated boosters or repeated infections to maintain high levels of protection against severe outcomes.