Actually, the ability to respond to never-seen-before threats is the whole purpose of the adaptive immune system [1].
> How would that POSSIBLY work?
Through a process called V(D)J recombination [2]. Essentially, every lymphocyte gets a different receptor of random shape, and purely by chance there will be a few lymphocytes with a receptor that matches the shape of the invading viruses (in most cases).
> How would that POSSIBLY work?
Through a process called V(D)J recombination [2]. Essentially, every lymphocyte gets a different receptor of random shape, and purely by chance there will be a few lymphocytes with a receptor that matches the shape of the invading viruses (in most cases).
[1] https://en.wikipedia.org/wiki/Adaptive_immune_system
[2] https://en.wikipedia.org/wiki/V(D)J_recombination