The iShares Biotechnology ETF is trading at new highs and 18 out of its top 20 constituents are green for the year.

MRK, MRNA's cancer vaccine breakthrough could revive the mRNA trade, putting biotech and genomics ETFs back in focus.

Major U.S. indices closed higher on Wednesday, with the Dow Jones Industrial Average rising 0.22% to 53,463.05.