WASHINGTON, Dec 27 (Reuters) - President Joe Biden said on Monday he would support an effort to shorten COVID-19 quarantine requirements for those who test positive for the novel coronavirus if U.S. health authorities recommend such a change. U.S. health authorities currently recommend a 10-day quarantine period for most Americans who test positive for COVID-19 but last week said healthcare workers who contract the virus can return to work after seven days of isolation. read more