NEW YORK CITY - A Brooklyn neighborhood saw novel coronavirus cases rise after a large wedding in the area, Mayor Bill de Blasio said Tuesday.
Borough Park - a neighborhood next to Sunset Park, which has also seen an uptick - saw 16 new cases that raised concern, de Blasio said.
"We now have capacity, when we see a problem, to address it with a lot of energy," de Blasio said. But he urged New Yorkers, "Avoid large gatherings."
Disease detectives will investigate whether the wedding, which had more than 50 guests, was the root of a substantial spread, de Blasio said.
The city will reach out to catering halls to clarify such gatherings are not allowed, but it remains unclear whether they will face punishment.
The uptick raised questions about herd immunity, the concept that a large number of people who have recovered from COVID-19 can prevent large outbreaks.
About a third of New Yorkers have had contact with the virus, a level not high enough to trigger herd immunity, said Senior Health Advisor Dr. Jay Varma.
"Everybody should consider themself at potential risk of infection," Varma said.
Borough Park will get a Test + Trace Corps blitz similar to the one seen in Sunset Park with a barrage of robocalls and increased testing capacity, officials said.
Sunset Park's uptick - determinted not to be a cluster situation - was also linked to large events; two latenight raves.
"A cluster is when we have a bigger and more sustained problem," de Blasio said. "That, thank god, is not what we're seeing in the case of Sunset Park."
As Borough Park saw numbers rise, the city reached a landmark low in one of its tracking indicators, de Blasio noted.
New York City reached a 0.24 percent testing rate, its lowest since COVID-19 first began its spread in March, the mayor said.
"This is striking," de Blasio said. "The more we do to beat back this virus the more we can do to bring back this city."