With the World Cup just months away does injuries to major star effect their team morale in any way. Neymar for Brazil he's their talisman and if he fails to recover it'll be a big loss, harry for England, and ageuro for Argentina they all are nursing injuries. I feel this World Cup could be dull due to injuries and secondly the hostile nature of the host is not doing any good to participants.
Injuries just two months prior to the world cup are a devastating blow for any team, to see that one of your teammates (especially someone from the starting XI) might not play in the world cup after years and years of preparation...I think it does affect the team morale.
For example, Neymar, he's the leader of national team, the best player in Brazil, the guy who couldn't play in some games in the last world cup due to an injury, the whole team was expecting to see him play in this World Cup...but just imagine how sad and worried his teammates must be right now after watching him on TV the other day using crutches, he could barely sit on the chair. So yes, injuries affect the team morale, but they're profesional players so i'm sure they know how to deal with these sort of situations.