It's a little time to be mature at that age. They don't always hurt anyway, and why would they, when they are going to become better than they felt currently at the time? I can foresee crying at maybe 7-10 shots, but only one? Come on! Kids are wimpy these days.
If its your child encourage them to be brave during shots but its unhealthy to think of them as wimpy. Thinking it or saying that invalidates the fact that they are frightened. Be comforting and supportive ir the fear will worsen. If its you, dont worry. Everyboy has something thta frightens them and its not your fault if yours is more obvious or taboo. Could be aichmophobia.