FILE PHOTO: A worker cleans the floor of the New York Stock Exchange (NYSE) as the building prepares to close indefinitely due to the coronavirus disease (COVID-19) outbreak in New York, U.S., March 20, 2020. REUTERS/Lucas Jackson

NEW YORK (Reuters) - At least two more New York Stock Exchange floor traders tested positive for the coronavirus on Tuesday despite measures taken to prevent people infected by the virus from entering the exchange while it remained physically open last week, according to a memo seen by Reuters.

"Given the possibility of exposure, and consistent with local, state, and federal government guidance, we recommend that all those who worked on the NYSE Trading Floor over the last 14 days should self-quarantine until a two week symptom-free period has elapsed," Intercontinental Exchange Inc ICE.N-owned NYSE said in a memo to traders.

New York City, home to more than 8 million people, has become a hot spot in the coronavirus pandemic, with 157 deaths and some 15,000 cases of COVID-19 reported as of Tuesday.

The NYSE kept its trading floor open last week, screening everyone entering 11 Wall Street, but temporarily shuttered the iconic open outcry space after market close on Friday, two days after a floor trader and an ICE employee tested positive for the virus.

At the time, the NYSE said neither person who tested positive with the virus had entered the building thanks to strict screening efforts and that it felt comfortable remaining open until the shift to fully electronic trading for the first time the exchange’s 228-year history the following week.

But the traders who tested positive on Tuesday were working on the floor last week in close quarters with other traders, according to a person with direct knowledge of the situation who asked to remain anonymous given the sensitivity of the matter.

“Those previously tested whose results remain outstanding will be notified directly by the medical team when results become available,” the NYSE said in the memo.

NYSE has not publicly commented on the new cases.

While the NYSE trading floor is temporarily closed over the health concerns, U.S.-listed stocks continue to trade electronically across all 13 active U.S. stock exchanges.