Pfizer Inc. PFE, -0.51% said Tuesday it will help develop and distribute BioNTech SE's COVID-19 vaccine candidate, though the deal excludes China. BioNTech BNTX, +0.32% , a German life sciences company, plans to put its vaccine candidate, BNT162, into clinical trials in late April. This includes clinical trials in Germany and the U.S. It is also partnering with Shanghai Fosun Pharmaceutical Group Co. Ltd. to commercialize its vaccine candidate in China. Pfizer and BioNTech in 2018 had announced plans to develop mRNA-based influenza vaccines. BioNTech's stock soared 58% in premarket trading on Tuesday and is up 18% year-to-date. Shares of Pfizer were up 3% before the market opened; the stock is down 22% year-to-date. The S&P 500 SPX, -1.11% has dropped 26% year-to-date.