Yes, perfect example that immunity exists (for more than a few months).

From the article: His viral load -- the amount of virus he had in his body -- went down over time, suggesting that his immune system was taking care of the intrusion on its own.

The guy was in Spain at the top of the dissease. Must have been in a room with a really ill person, so inhaled a lot of virus particles. These particles were destroyed by the immune system.

So, next one please.