It was almost a month before school starts and 7-year-old Olivia Magistre Victores was going through a familiar ritual at the Little Haiti Health Center in Miami:

A cold swipe of alcohol on bare skin. A nurse’s gloved fingers bracing her upper arm. Another nurse cooing: respira profundo, respira profundo. Deep breath, deep breath.

Then — so fast it’s hard to see — a plunge with a small needle.

Olivia has to come back to the clinic in September for some required booster shots. She is one of the thousands of Miami-Dade County students who will have incomplete vaccinations when school starts a week from Monday.

But she will not be turned away from school. Kids without the required vaccinations are allowed to go to class under a provisional status.

As a result, a striking number of children in Miami-Dade lack the required immunization shots. The facts:

•  Statewide, 91.1 percent of public school children began kindergarten in 2010-11 with complete immunizations.

•  In Broward, the percentage was 92.9 percent; in Palm Beach it was 90.4 percent, and in Monroe County, 93.6 percent.

•  But in Miami-Dade, only 76.7 percent of kindergartners had complete immunizations, the lowest percentage by far of Florida’s 67 counties.

County, state, and school health officials say they don’t know why Miami-Dade’s vaccination rate is so low. In Olivia’s case, her family came recently to the United States from Cuba, and her mother, Dunay Victores, says her daughter had her shots in their homeland but doesn’t have the documentation to prove it.

The influx of Haitians after last year’s calamitous earthquake could also be a factor.

However, New York City has similar percentages of immigrants in public schools, and yet fewer than 1 percent of children start school without the necessary shots.

For a while, there were scare stories on the Internet about certain immunizations being linked to autism, but those seem to have died down, said Lydia Sandoval, the registered nurse in charge of immunizations for the Miami-Dade County Health Department.

Whatever the cause, there is concern among local health officials that the low rate puts students and their communities at higher risk of catching ailments like measles, mumps and whooping cough that were once nearly eradicated.

So far this year, the United States has had 156 cases of measles —the most since 1997, and most of them in unvaccinated children. Florida has had seven measles cases — all in unvaccinated kids.

Last year, Miami-Dade had 29 cases of whooping cough and three cases of mumps.

“We’re not dismissing this,” Lillian Rivera, administrator with the Miami-Dade County Health Department, said of the drop in the percentage of those vaccinated. “We’re worried about it.”

BACKSLIDING

Just five years ago, 92.8 percent of kindergarteners in Miami-Dade schools had their immunizations completed. That was in line with the statewide average of 94 percent. By 2010-2011, that had changed dramatically. Miami-Dade found itself nearly 15 percentage points below the statewide average.

On March 7, Dr. Shairi Turner, deputy secretary for health of the Florida Department of Health, sent a memo to all county health departments asking for action to “decrease the occurrence of vaccine-preventable diseases by increasing immunization coverage levels among school-age children.” The goal for kindergartens, she reminded them, is “at least 95 percent.”