LOS ANGELES (CNS) — Los Angeles County has reached the milestone of fully vaccinating half of its population aged 16 and over against COVID-19, the public health director announced Monday, but lagging rates among those aged 30 to 49 have made them the most likely to wind up hospitalized with COVID-19 infections.

According to figures released Monday, nearly 4.2 million county residents have now received two doses of vaccine and are considered fully vaccinated.

"We can now proudly say that more than 50% of L.A. County residents 16 and older have received two doses of the vaccine," county Public Health Director Barbara Ferrer said. "It is truly thrilling to see us reach this landmark, and I want to thank everyone who's done their part to get us to this point."

Since they've been eligible for shots longer, the 65-plus age group has the highest rate of vaccinations, at 72%. Among those aged 16-17, the rate is 28%, while the 16-64 group is at 46%.

While improvements continue to be made in each group, Ferrer noted that "lower vaccination rates in younger age groups means not only are people in those age groups more likely to transmit COVID, but they're also more likely to suffer its severe consequences."

According to Ferrer, between April 1 and May 15, the 30-49 age group had the highest number of people hospitalized due to COVID-19, at more than 600.

"This is the first time over the course of the pandemic that we've seen this happen," she said. "Before April, this age group consistently saw lower hospitalization rates when compared to other age groups. If we look at a different six-week period, last October pre-surge, we can see a stark difference. Even when our numbers were not at their highest, older people have always been more likely to be hospitalized."

She attributed the sudden change to a "gap in protection."

"Older adults, particularly those over 65, are now protected by their high vaccination rates," she said. "Children and young adults may be protected by virtue both of their youth and by the masking requirements in place at their schools. But people in the middle group — many of them are workers and people responsible for the care of others — are not as well-protected by either of these factors. And if they're not vaccinated, they are highly likely to end up with a COVID infection, and unfortunately, as we see, disproportionately likely to end up in the hospitals."

She said the county is continuing to press the need for more people to get vaccinated, but overall demand for the shots continues to dwindle, with only about 118,000 doses administered across the county population for the week that ended Friday.

"This is an underestimate of the true number because we have incomplete data for these dates and we don't have data from the weekend," she said. "But nonetheless, it's clear that we need more folks coming in for the first-dose appointments in order to create the conditions that can sustain our full reopening in a few weeks."

In hopes of getting more people to vaccination sites, the county plans to offer more incentives, with prizes such as gift cards and sports tickets likely to be offered in coming weeks. Ferrer said the giveaways will be announced through the county's social media platforms.

Over the weekend, people over age 18 who got vaccinated at county- or city-run sites were given a chance to win Laker season tickets. Ferrer said sports teams and local event venues are chipping in to provide additional incentives in hopes of boosting vaccination rates ahead of the planned June 15 lifting of the bulk of COVID restrictions across California.

"Now is a particularly critical time," she said. "We are less than a month out from fully opening up this county with very few restrictions. Our case rates are low and we want to be in as strong a position as possible when the risk of transmission could go up, which can happen after June 15. So we're doing everything we can to get people the information and the good reasons they need to get vaccinated now.

" ... While these opportunities to say 'thank you' are not themselves enough to get all unvaccinated Angelenos into a vaccination site, we hope for some, they help. However, the most important work to be done with the largest impact is engaging with residents in our communities to provide high-quality information about the vaccines, to dispel false myths and to answer all of your questions."

The county reported just four new COVID-19 deaths on Monday, lifting the overall death toll to 24,175.

Another 139 infections were announced by the county, while Long Beach reported eight and Pasadena five, raising the total from throughout the pandemic to 1,238,931. Ferrer noted that the death and case numbers were lower than usual — even for a Monday — due to weekend reporting lags and delays in reporting from several local testing labs.

According to state figures, there were 325 people hospitalized in the county due to COVID-19 as of Monday, up slightly from 319 on Sunday. There were 73 people in intensive care, up from 72 on Sunday.