We went a few months back, didn't take Malaria Meds. (It's a tablet you take before, during, and after)
I was sure there was no Malaria in Fiji, but i could be wrong?! ETA- just looked on on few sites, they all say no Malaria in Fiji?!

The side effects can be pretty horrible from the tablets and i'm not sure that babies can even take them. Worth checking with a travel Dr if you are worried about it.