Wall Street’s main indexes opened higher on Wednesday after Pfizer and BioNTech said a three-shot course of their COVID-19 vaccine was shown to have a neutralizing effect against the new Omicron coronavirus variant in a laboratory test. The Dow Jones Industrial Average rose 2.58 points, or 0.01 percent, at the open to 35,716.85. The S&P 500 opened higher by 4.11 points, or 0.09 percent, at 4,690.86, while the Nasdaq Composite gained 3.73 points, or 0.02 percent, to 15,690.65 at the opening bell.