Vaccinations among residents 12 and older fell precipitously week-over-week across Miami-Dade, Broward and Palm Beach counties — but so did COVID-19 cases and positivity rates as the summer wave of infections continues to subside across South Florida.

All three counties are now reporting the lowest case numbers and positivity rates — the share of COVID-19 tests that come back positive for the virus — since late June.

Despite having the lowest vaccination rate in the tri-county area with 74% of residents inoculated, Palm Beach County saw the steepest drops in positivity rate and total cases, according to figures the Florida Department of Health released Friday.

Palm Beach this week counted just 681 positive COVID-19 cases, a nearly 77% drop, and recorded a positivity rate of 1 percentage point lower than last week.

But far fewer Palm Beach residents were vaccinated this week compared to the week prior or even before COVID-19 infections again began to surge three months ago. Last week, 6,067 people in Palm Beach got a shot. This week, just 1,778 did — a 71% dip.

In Miami-Dade, which boasts the state's highest vaccination level at 91%, total case numbers fell 41%. The positivity rate fell 1.6 percentage points.

Vaccinations in Miami-Dade are similarly petering out. They sank 22% there week-over-week.

In Broward, positive cases fell by 20%. The percentage of residents there who have been vaccinated was the only one among the three counties to rise this week, growing by 1 percentage point — the same amount by which the county's positivity rate fell.

Broward's vaccination rate falloff slightly outpaced Miami-Dade's, with 23% fewer shots administered.

With boosters of the Pfizer vaccine being administered across the state, Florida's vaccination rates may again rise as previous recipients get a third shot. And with 40 million doses of coronavirus vaccine doses available, U.S. health authorities have said there will likely be enough for both qualified older Americans seeking boosters and young children for whom vaccine clearance seems imminent.

Eligible recipients of the booster now include people 65 and older; people between 50 and 64 with underlying health conditions like obesity, diabetes, chronic kidney disease or other compromising conditions; people between 18 and 49 based on their individual risks; and people 18 to 16 whose jobs heighten their risk of exposure, such as health care workers, teachers and day-care workers.

Here are some of the weekly numbers for the previous three weeks throughout the South Florida tri-county area:

Miami-Dade

— Sept. 10-16: 7,423 newly confirmed cases, 5.8% positivity rate, 22,372 vaccine doses administered, 90% of 12-and-up population now vaccinated

— Sept. 17-23: 8,556 newly confirmed cases, 5.3% positivity rate, 16,813 vaccine doses administered, 91% of 12-and-up population now vaccinated

— Sept. 24-30: 5,027 newly confirmed cases, 3.7% positivity rate, 13,138 vaccine doses administered, 91% of 12-and-up population now vaccinated

Broward

— Sept. 10-16: 5,503 newly confirmed cases, 7.8% positivity rate, 12,894 vaccine doses administered, 80% of 12-and-up population now vaccinated

— Sept. 17-23: 4,349 newly confirmed cases, 6.6% positivity rate, 9,594 vaccine doses administered, 80% of 12-and-up population now vaccinated

— Sept. 24-30: 3,462 newly confirmed cases, 5.5% positivity rate, 7,363 vaccine doses administered, 81% of 12-and-up population now vaccinated

Palm Beach

— Sept. 10-16: 4,568 newly confirmed cases, 10% positivity rate, 8,165 vaccine doses administered, 73% of 12-and-up population now vaccinated

— Sept. 17-23: 2,921 newly confirmed cases, 7.5% positivity rate, 6,067 vaccine doses administered, 74% of 12-and-up population now vaccinated

— Sept. 24-30: 681 newly confirmed cases, 5% positivity rate, 1,778 vaccine doses administered, 74% of 12-and-up population now vaccinated