New York City's seven-day average of new coronavirus cases is "cause for concern," Mayor Bill de Blasio said on Tuesday.
The city recorded 605 new cases on a seven-day average.
"We are watching that very carefully," de Blasio said. "Some of that again is because of a lot more testing, but it's still cause for concern."
The daily number of people admitted to hospital with Covid-19 in New York City is at 83.
Meanwhile, the percentage of people who tested positive for Covid-19 across the city is "clearly aberrant" at 0.38%, Mayor de Blasio said.
"We've seen that from time to time when surprisingly low number of test results have come in for the day. That can vary by day, that number will change and go upwards as more test results come in," said de Blasio, adding that the truest number is the 7-day rolling average, which is at 1.59%.
New York -- once the epicenter of the pandemic as the largest and densest city in the US -- began gradually reopening in June.
In total, New York City has recorded 256,881 coronavirus cases, 19,355 confirmed deaths and 4,662 "probable deaths" related to Covid-19, according to figures released Monday by the city's public health agency.