Here's why:
* The Pokerus is a virus: It's a contagious condition that affects Pokemon, not eggs.
* Eggs are not alive: They are simply containers for potential Pokemon.
* The Pokerus spreads through contact: This means a Pokemon must be directly exposed to another Pokemon with the Pokerus to catch it.
Therefore, an egg cannot catch the Pokerus because it's not a living Pokemon and cannot come into contact with infected Pokemon.