DUBLIN – Merck & Co. Inc. is placing two separate bets on recombinant viral vector technology in a broad effort to tackle COVID-19, in which it is also in-licensing a small-molecule antiviral drug. Kenilworth, N.J.-based Merck is acquiring Austrian vaccine developer Themis Bioscience GmbH in a move that propels the latter firm’s COVID-19 vaccine program to the front ranks of the industry pipeline. It is entering a COVID-19 vaccine development collaboration with the not-for-profit vaccine research organization IAVI.