Vaccine question

Telyco

Does anyone know why kids can get a few shots in a day but then can't get another one for a month? Evan needed his MMR and chickenpox before starting school. He got the MMR at his appt yesterday but can't get another for a month even though they wanted to give him both yesterday. We want him vaccinated before he starts school, but they'll take a doctors note saying he isn't eligible to get it until the 6th (he starts on the 3rd)