Through most of the pandemic, the county's Latino population had experienced the highest rates of the virus.
Case rates, hospitalizations and deaths in all county populations have dropped significantly since the winter surge, as vaccinations continue to increase.
But in the last two weeks, county officials have seen a shift.
"You can see that the highest case rates are now among Black residents at 45 cases per 100,000," said county public health director Dr. Barbara Ferrer.
Besides the highest infection rate, Ferrer say African Americans are also seeing the most hospitalizations and deaths.
"This is definitely a flip and something we're going to watch very carefully," Ferrer said.
Ferrer says the higher rates in African Americans go hand-in-hand with the data showing that population has received the fewest doses of vaccine at 40%, compared to 71% for whites.
Ferrer notes that the overwhelming majority of people who are hospitalized for COVID-19 are unvaccinated.
To encourage vaccinations, California also announced one of the biggest vaccine lottery incentive programs in the nation, offering more than $116 million in cash prizes.
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And the LA County Health Department is offering incentives too. Starting Friday, residents getting a first dose or anyone getting a second shot who brings a first-time vaccine recipient will have a chance to win tickets to LA Kings and LA Galaxy games.
The Los Angeles City Council has also just approved paid sick time off for people getting the vaccine as well as eight hours of recovery time from any side effects. This new measure heading to Mayor Eric Garcetti's desk will cover businesses of any size.