Shares of Johnson & Johnson /zigman2/quotes/201724570/composite JNJ -2.55% were down 0.3% in premarket trading on Thursday after CFO Joseph Wolk told CNBC that the company expects the Phase 1 trial for its COVID-19 vaccine candidate to begin next week. J&J reported second-quarter earnings on Thursday. Wolk said the Phase 1 trial is expected to enroll more than 1,000 participants, primarily between the ages of 18 and 55 years old, although the company also plans to include a group of people who are 65 years old or older in the early-stage trial. He also said that J&J is in talks with the National Institutes of Health to move up the timeline for the anticipated Phase 3 trial to late September. "The science still has to play out," Wolk said. J&J's stock is up 1.6% year-to-date, while the S&P 500 /zigman2/quotes/210599714/realtime SPX -1.63% is down 0.1%.