U.S. stock benchmarks traded mixed early Wednesday as investors weighed the efficacy of vaccines and treatments against the omicron variant of coronavirus that causes COVID-19. Pfizer /zigman2/quotes/202877789/composite PFE -1.60% and BioNTech /zigman2/quotes/214419716/composite BNTX +0.26% said Wednesday that a third dose of their CCOVID-19 vaccine neutralized the new strain in lab tests, but that a two-dose regimen was much less effective. The Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA -1.63% was up less than 0.1% at 35,737, and the S&P 500 index /zigman2/quotes/210599714/realtime SPX -1.65% was trading less than 0.1% lower at 4,687. The Nasdaq Composite Index /zigman2/quotes/210598365/realtime COMP -1.60% was down 0.3% at 15,637.








