Does post vaccination high fever cause developmental delay or any kind of brain damage in younger babies if left untreated? My baby is 2.5month old...Doctor didnot tell us to give paracetamol after vaccination..my baby got all the shots at the same day later baby was suffering from high fever after vaccination continued for 24hours...bt we left it untreated.we came to know from net tht all vaccines given at same visit and high fever cause developmental delay r brain damage.w e r worried ..