Mayor de Blasio allegedly blew a chance to boost the coronavirus vaccine rate because his health officials failed to get a vaccine distribution van to a big public event in the city’s least inoculated neighborhood, one local official revealed.

State Sen. James Sanders Jr. said he was sure he could have gotten hundreds of jabs into people on the spot, but de Blasio’s health office was so paralyzed by bureaucracy that they demanded at least a week’s notice before sending out the vax vehicle.

“We just did an event in the Rockaways. Close to 1,000 people. We requested the truck. It did not come,” Sanders said at press conference Thursday in Far Rockaway.

The Queens Democrat said he gave out 300 masks at the Function Injunction community gathering in Far Rockaway last Saturday. He believes he could have enticed around the same number of people to get vaccinated.

“It was a missed opportunity,” Sanders told The Post after the press conference.

The beachside community has the lowest vaccination rate across the five boroughs with just 38.85 percent of residents who’ve gotten at least one jab compared to the citywide average of 60 percent.

A city Health Department spokesman said Sanders didn’t give officials enough lead time to get a van to his event.

They need one to two weeks of advance notice to get one of the city’s 70 mobile vaccination vehicles to requested locations, the rep said.

The department does not prioritize availability for high-risk neighborhoods like Far Rockaway, the rep said.

Stephanie Guzman, a spokeswoman for the city’s Vaccine Command Center, said Sanders “did not mention that the request for a vaccine site near Bayswater Park was submitted with one day’s notice and organizers were notified of it not being feasible.”

“However, at least five vaccine vans have been scheduled for the region in the coming days,” Guzman said. 

Sanders, Queens Borough President Donovan Richards and other local leaders wrote the mayor Monday asking him to send mobile vaccination vans to all public events across the city to protect residents from the aggressive Delta variant of the coronavirus.

Sanders said the idea was a “common sense” approach. The mayor’s office did not immediately return a message seeking comment on the letter.

Richards warned that low vaccination rates in areas like Far Rockaway could return the city to the dark days of the pandemic’s peak last year.

“Right now we’re at a pivotal moment in this fight. We don’t want to go back to where we were,” he said at the press conference at the city’s Beach 39^th Street Vaccine Hub, where about a half dozen people were waiting to get the jab.

“Reminder: Far Rockaway shut down. Reminder: there were bodies upon bodies in our hospitals. Reminder children were having to learn on Zoom. This is a matter of life and death,” Richards warned.