My first time GMing, I'm trying to get a small group going with 5E, and it seems no one has much interest in playing Cleric or Paladin.

So, my question: among the many new-found freedoms granted by 5E, can a party be effective without either of these? The session I'm running is a one-shot 'intro,' so, I guess I could reduce the challenge rating. The following week, however, another buddy is GMing Hoard of the Dragon Queen--can a party succeed without either of these classes (no spoilers, please)?