Concerns are growing in New York City as the number of COVID-19 cases in certain neighborhoods continues to rise.

In a news conference Thursday, Mayor Bill de Blasio stressed that there is no herd immunity when it comes to COVID-19.

Health officials say they are extremely concerned about four main COVID-19 clusters.

The city has been setting up mobile testing sites, asking people to get tested even if you’re not showing symptoms

The city’s Health Department says there are 11 neighborhoods in the city with positive rates above 3% and seven more neighborhoods that they are keeping a close eye on.

In addition to getting tested, they are asking people to avoid large gatherings, especially indoors. The department says if your house of worship has reopened, to please wear a mask and not share any utensils.

Today the mayor says they are opening a COVID-19 block party on Avenue U and West 13th Street. This means is entire block will be converted into a testing site.