Vitamin C & other ways to boost immunity???

FirstTimePregnancy

Does anyone know how much Vitamin C is safe to take while pregnant?  I used to take Emergen C 1000 mg drink mix, but am not sure if that would be overkill during prenancy or not.  Are there any other ways that you have been boosting your immunity?  I have been sick my entire pregnancy and have missed a significant amount of time from work...I just CAN'T be sick anymore and something has to give!  Any insight would be greatly appreciated!  Thanks in advance!