Unfortunately Wakefield's paper that essentially kicked off the "MMR vaccine controversy" was published by the Lancet. They eventually retracted but enormous damage was done (including deaths apparently).

For the unknowing, the Lancet was at the time this paper was published considered to be a top-tier medical journal; the equivalent of Nature or Science for medicine.

I cannot speak to its prestige now, however. I'm sure that its reputation was somewhat damaged by publishing this paper but I imagine it's still considered a "good" journal.