Why Wasn't It Pink?

To the Editor: I recently used a dosage of triple live vaccines (rubeola, rubella, and mumps), and on injecting the diluent into the vial withdrew a clear fluid. Past experience has always resulted in a pink to red color of the fluid on reconstitution. The question of efficacy of the product was the basis of my making inquiry of the manufacturer. Attached is a letter explaining the variations in color. I believe that the main