Mayor Bill de Blasio faced questions Monday on what his administration is doing to address low vaccination rates in some neighborhoods as the city faces a growing number of COVID-19 cases caused by the delta variant. 

In eastern Brooklyn and southeast Queens just over a third of residents are fully vaccinated, while in much of the Bronx just 40% of residents are fully vaccinated, according to city data. In much of Manhattan, western Brooklyn and northern Queens, two-thirds or more of residents are fully vaccinated. 

Just over half of all city residents are fully vaccinated, and city statistics show the cumulative number of vaccinated people plateauing significantly in recent weeks. 

Scientific studies show that full vaccination is crucial for defending against further COVID-19 infections caused by the delta variant. 

De Blasio has touted the city-sponsored prizes that residents are entered to win if they get vaccinated at a city-run site, including cash prizes and “staycation packages,” and that residents can request an in-home vaccination. 

The mayor said that the city was going to continue with its current efforts to increase vaccination levels. 

“Clearly one of the things that's necessary is deepening the grassroots effort,” he said. “There’s still a lot more we can get done that way.” 

In the city, hospitalizations have remained between roughly 60 and 80 patients each day for several weeks. The number of deaths due to COVID-19 has fluctuated between 3 and 5 per day for just under three weeks.

The number of reported cases on the seven-day average has ticked up slightly for the first time in months, to 328 on Saturday from about 250 two weeks earlier. The reported cases remained below the 500 threshold that the city has used to signify a significant change in the severity of the pandemic. 

Dr. Dave Chokshi, the city health commissioner, said it was important for the city and others to spread the message of “urgency” around vaccination, because the delta variant is more infectious, and may cause more severe injury, than earlier strains of the virus. 

“The spread of the delta variant means that it's perhaps the most dangerous time to be unvaccinated,” Chokshi said. 

On Sunday, Eric Adams, winner of the Democratic mayoral primary, recommended that New Yorkers wear masks to “err on the side of caution.” 

Health experts have suggested that, with the decline in cases and hospitalizations due to the virus slowing down in recent months, simple measures like encouraging or requiring mask wearing in more settings could further drive the virus out of the city. 

De Blasio defended current mask guidance, which requires mask wearing in public settings like mass transit and hospitals, but not in private businesses. 

“From what we have heard from the CDC, from what we've seen from our own experience, the current guidance makes a lot of sense,” he said.