What happens when i miss a dose of peginterferon alfa-2a ?

Report it: When you miss a dose of peg interferon, you should report it to your treating physician. If it is just one dose, chances are you may have it injected later that day or week. If it is not feasible, i think you will still need to continue on with your treatment, as one dose is unlikely to change the trend you've had. Talk to you doc, though.

Not much: you should try not miss a dose of medication, if you miss a dose of PEGinterferon your side effects might lessen and the serum drug level will decrease. Overall if you miss only one dose, and complete the rest on schedule, the effect should not affect the outcome of your treatment.