U.S. stock indexes Tuesday rose modestly higher as traders grappled with concerns over how the global economy will withstand COVID-19's delta variant as well as Chinese regulatory actions. The Dow Jones Industrial Average /zigman2/quotes/210598065/realtime DJIA -0.17% rose 0.3% at 34,924, the S&P 500 index /zigman2/quotes/210599714/realtime SPX -0.84% advanced 0.2% at 4,395, while the Nasdaq Composite Index /zigman2/quotes/210598365/realtime COMP -1.92% climbed 0.1% to reach 14,702. The market has been buoyed by strong corporate quarterly results but investors are still watching to see if the U.S. central bank will continue to support the economy, helping to spurt further expansion for equities. The Centers for Disease Control and Prevention said Monday the delta variant is "highly contagious" and urged unvaccinated people to get their shots and for employers to require vaccination. "To put this in perspective: if you get sick with the alpha variant, you could infect about two other unvaccinated people," said CDC Director Dr. Rochelle Walensky. "If you get sick with the delta variant, we estimate that you can infect about five other unvaccinated people - more than twice as many as the original strain," she explained.