Sure thing! The Virus & Immunity cards are only used with 4 players. You will shuffle all of the cards and deal all but 2 cards to the players. Each player should have the same number of cards. Here are the possible options and how they are played and scored:
A player is dealt the Virus and Immunity cards. In this case they cancel each other out. The player discards both cards and picks up the 2 cards from the draw pile. They score 5 bonus points for being invincible!
A player is dealt the Virus card only. They are out for that round and score 3 pity points. Their cards are placed face down on the table and the rest of the players each pass 2 cards, make their bids, and play as usual. They bid and play without knowing which cards are out of play for that round.
A player is dealt the Immunity card only. They keep that card in their hand and can play it in any trick. It is the most powerful card in the deck and wins any hand in which it is played. For example, if someone plays a Vaccine card, a player with the Immunity card can “over trump” them with the Immunity card and win that round.