The original antigenic sin: How childhood infections could shape pandemics

A child's first influenza infection shapes their immunity to future airborne flu viruses - including emerging pandemic strains. But not all flu strains spur the same initial immune defense, according to new findings published today. The results are relevant to the COVID-19 pandemic, according to the senior author, who says they may explain age-based distributions of SARS-CoV-2 disease severity and susceptibility.

source https://www.sciencedaily.com/releases/2021/02/210218142817.htm