naomi ruccum, cbs news, new york. >> for some of you the news continues.heck back later for cbs news this morning and follow us online anytime at cbsnews.com. reporting from the nation's capital, i'm ed o'keefe. ♪ ♪ captioning sponsored by cbs >> o'donnell: tonight, the u.s. approaches nearly four million cases, as the c.d.c. warns the number of infections could be much higher than reported. a new study finds people without symptoms, or those who didn't seek medical attention, could be silently spreading the virus. and, the three simple things that could stop large outbreaks. plus, what we're learning tonight about when the top vaccine candidates will be ready for use. new travel warning. more than half the country now must quarantine when visiting new york. what you should know before you make the trip. china tries to steal vaccine research. the f.b.i. puts out a wanted poster for two chinese nationals charged with attempting to hack u.s. biotech firms.